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The
Nervous
system
The Tor ah of Life
An Integrated Torah-biology Textbook For Jewish High Schools
Rabbi Yitzchak Ginsburgh
Professor Eliezer Zeiger
About the
Authors
Rabbi Yitzchak
Ginsburgh
is our generation’s
most respected
authority
on a unified view
of Torah and
science. He excels in the understanding
of many scientific disciplines and their
connection to Kabbalah and Chassidic
philosophy. He is the author of more
than one hundred books in Hebrew and
English, including The Hebrew Letters,
The Mystery of Marriage, Body, Mind and
Soul, and The Art of Education. Rabbi
Ginsburgh is outstanding in his ability
to teach ancient Torah knowledge in the
language of our times.
Professor Eliezer
(Eduardo) Zeiger
is Professor
Emeritus of
Biology at the
University of
California,
Los Angeles, and has written about one
hundred scientific papers. He is the coauthor of a leading textbook in plant
biology that has been translated into ten
languages and published in five successive
editions. Professor Zeiger has been a
student of Rabbi Ginsburgh since 1992,
and is the founder and CEO of The Torah
Science Foundation.
art on Cover - “Light from the Einsof* by Tuvia Katz
Torah of Life – An Integrated Torah-biology Textbook
i
Introduction
Biology is the study of life. In the Garden of Eden
there were two trees: the Tree of Life and the Tree of
Knowledge. A tree, with its roots, trunk, branches,
foliage, and fruit, symbolizes a developmental
program that starts with a germinating seed and
culminates in fruits and new seeds. The Tree of Life
symbolizes the creation of life, and the evolution of
life from the perspective of the Torah.
“Knowledge” in Hebrew also means “consciousness.”
The Tree of Knowledge of Good and Evil symbolizes
the “tree” of conscious living forms, the pinnacle
of which is man. The Torah is both the unfolding
story of life and the unfolding story of human
consciousness. It bestows life on those who walk
in its path and corrects our state of consciousness,
teaching us to know what is good and what is not,
and to focus on what is good. Thus we may say that
the Tree of Life is the “tree” of integrated Torahbiology and the Tree of Knowledge is the “tree” of
integrated Torah-psychology and the understanding
of human consciousness.
Integration of Torah and science requires a common
frame of reference, a model that fits both Torah and
science. The foundation of this model is the essential
unity of the Creator and His creation. The language
of this model is provided by Kabbalah, the most
“scientific” aspect of the Torah. Kabbalah provides
the language that reveals the correspondence
ii
Chapter 08 – Nutrition
between key Torah concepts and their scientific
counterparts. At the core of this unifying language
are the sefirot (often referred to themselves as the
Tree of Life), the lights and channels of both life
and consciousness that flow from the Creator to
His creation.
In contrast to the all-encompassing unity of the
Creator and His creation, ordinary reality appears
fragmented and devoid of purpose. Biology courses
in Jewish schools often reflect this fragmentation,
describing a reality in which the presence of the
Creator is completely hidden.
We present here a pilot chapter of a Torah-biology
textbook aimed at properly reflecting the true unity
of creation. Biology, the science of life, is optimally
suited for that purpose. The chapter alternates
between science and Torah knowledge, always
aiming at their integration. The ultimate purpose
of this approach is to create a divinely oriented
consciousness, which should help bring us back to
the unadulterated consciousness state of the Garden
of Eden.
Table of Contents
Chapter 1
Chapter 11
The Science of Biology
The History of Life
Chapter 2
Chapter 12
The Chemistry of Life
Life Diversity
Chapter 3
Chapter 13
Cell Structure and Function
Animal Behavior
Chapter 4
Chapter 14
Photosynthesis
The Human Body
Chapter 5
Chapter 15
Cellular Respiration
The Nervous System
Chapter 6
Chapter 16
Cell Growth and Division
Skeletal and Muscular Systems
Chapter 7
Chapter 17
Genetics, DNA and RNA
Circulatory and Respiratory Systems
Chapter 8
Chapter 18
Nutrition
Digestive System
Chapter 9
Chapter 19
Human Genetics
Endocrine and Reproductive Systems
Chapter 10
Chapter 20
Scientific Evolution and Torah Evolution
Immune System
Torah of Life – An Integrated Torah-biology Textbook
iii
Chapter 08
Nutrition
IN THIS CHAPTER
• Food and Energy
• Nutrients
• Nutrition and a Balanced Diet
• Sources and References
FIGURE 8.1
Typical Foods Served on Jewish Holidays
Clockwise: matzah (unleavened bread), for Passover,
“blintzes” traditionally served stuffed with a cheese filling on
the festival of Shavuot; apples dipped in honey served at the
first meal of Rosh Hashanah; “latkes” fried in oil served during
Chanukah; we drink wine and eat hamantashen on Purim;
and challah bread prepared in honor of Shabbat and holidays.
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Chapter 08 – Nutrition
To see how important food is for most people, have a look at the groups
of people eating in a park on a national holiday. Eating is a primary
human activity. We all need to eat because we feel hungry if we don’t. Plus,
prolonged periods without eating result in starvation and bodily damage.
But food is even more than the nutrition it provides. Food is a basic aspect
of human culture. In many celebrations, such as Thanksgiving Day, a meal
serves as the focal point for a festive gathering of people.
Food is primarily nourishment, but to the human psyche, physical
nourishment suggests the need for spiritual nourishment as well. Expressing
thanksgiving nourishes the soul, just as food nourishes the body. If we sit
together, enjoy the presence of each other, tell stories, make plans, and
then join in a meal, a snack, or a drink, our hearts can open. Sharing food
together makes us more receptive and able to interrelate productively with
one another.
©Torah Science Foundation
In Jewish tradition each holiday has a special food that symbolizes the inner
meaning of the day (FIGURE 8.1). While eating the food, we consciously
internalize that meaning. On Pesach, the holiday commemorating
our liberation from Egyptian slavery, we eat matzah — unleavened
bread — symbolizing bondage and redemption. On Shavuot, the time of
the Giving of the Torah, we eat dairy products, for the Torah is likened to
milk. On Rosh Hashanah, the New Year, we eat an apple dipped in honey
to symbolize our desire for a sweet year. On Chanukah, we eat latkes and
cheese, reminding us of the heroism of Yehudit and the Maccabees. On
Purim, we drink wine and eat hamantashen, commemorating the feast of
Esther and the hanging of Haman.
Food and Energy
Why is food so important for our physical well being? Everything we do
during the day, such as walking, working, playing, or even thinking, requires
energy, and food is the substance which fuels our daily activities. A major
component of food is the chemical glucose. We learned in an earlier chapter
that cells convert glucose and other molecules into ATP, and ATP is the
chemical fuel of the cell (FIGURE 8.2).
FIGURE 8.2
Adenine
ATP
NH2
C
N
C
C
C
Energy Rich Bond
N
C
H
N
Adenosine triphosphate C10H16N5O13P3
N
H
O H
H2C
O
Ribose C
H
H
C
H
C
C
H
OH
OH
O
P
O
O H
O
P
O
O H
O
P
O
Phosphate Groups
O
H
ATP, Adenosine triphosphate
ATP is a chemical compound consisting
of the nucleotide adenine, the five-carbon
sugar, ribose, and three phosphate groups.
The breaking of the chemical bond between
the second and third phosphate group
releases a relatively large amount of energy
that is used by the cell to fuel many energyrequiring processes
Torah of Life – An Integrated Torah-biology Textbook
801
Most people go about their daily routine of providing for their bodies what
nature requires — eating, drinking, sleeping etc. — without paying much
attention to what these activities and functions mean on a spiritual plane.
The questions that we need to ask are: Why did God create me this way? Why
do I have to eat in order to obtain energy?
The Torah teaches us: “Man does not live on bread alone, but rather man
lives on the word of the mouth of God.” In the Torah, the word “bread”
refers to food in general. What the above verse is teaching us is that the
“bread” we eat contains a Divine life force, and moreover, that it is important
for us to know that this life force is coming directly from God, the Creator
and Sustainer of all life (and indeed, of all reality).
If we eat our food with this realization in mind, we can extract the Divine
life force or Divine spark that is the inner essence of the food. As a result, the
level of nutrition — both physical, as well as cognitive and spiritual — that
we gain from the food will be much greater than if we eat without this
understanding.
©Torah Science Foundation
In Hebrew, “bread” (food), lechem, is related to “war,” milchamah (both
words come from the same root l-ch-m). The sages instruct us to eat “with a
sword in hand.” What does this mean?
FIGURE 8.3
Calorimeter
A calorimeter measures the heat released
by a substance, in our case, food, when the
substance is burned. From that information
it is possible to calculate the calorie content
of the food being burned. One ounce of
regular potato chips contains 150 calories.
One ounce of cheese sandwich made with
commercial white bread, cheddar cheese,
and margarine contains 115 calories.
Ignition Wires
Thermometer
Water
Burning
Food
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Chapter 08 – Nutrition
The “sword” is the consciousness necessary to pierce through the outer
“shell” of the food and reveal, i.e., redeem, the Divine spark trapped within
it. On the physical plane, the “sword” symbolizes the enzymes present along
the digestive track that chemically break down the food and allow for the
body to absorb its nutrients. The Torah teaches us to be conscious of what
takes place within our bodies, to recognize the spiritual implications of the
physiological processes that are responsible for our life and health. The Torah
wants us to connect in our consciousness that which is taking place on the
spiritual plane with that which is simultaneously taking place on the physical
plane, thus enriching both — more spiritual nourishment and more physical
nourishment.
If I am trying to avoid overeating and I have the choice between eating a
bag of potato chips or a cheese sandwich, which one should I choose? One
way to quantify the energy content of food is, surprisingly, to burn it! In the
body, food is processed very slowly by enzymatic reactions that metabolize
the food, step by step. In an automobile, the hydrocarbons in gasoline are
burned to power the car’s engine.
If we want to quantify the available energy in potato chips or a cheese
sandwich, we burn comparable amounts of the two types of food in an
instrument called a calorimeter (FIGURE 8.3), and measure the amount of
heat released in units called calories. One calorie is the amount of heat
needed to raise the temperature of 1 gram of water by 1 degree Celsius. It
is convenient to express the energy in food as kilocalories (kcal); one kcal
equals 1,000 calories. In food, one kcal is referred to as a dietary Calorie,
with a capital C. If you are an average-sized teenage girl, you will burn about
2,200 Calories per day (2,800 Calories per day for males). If you are playing
in a tournament and you engage in vigorous physical activity, you will burn
more calories.
The burning of food immediately brings to mind the Holy Temple in
Jerusalem, where numerous sacrifices were burnt on the altar every day.
The burning elevated the energy trapped in the sacrifice (from the animal,
vegetable, and mineral kingdoms) to a higher spiritual plane, dedicating it to
holiness and purity.
In the Temple service, the body of the sacrifice was offered up for God.
Because of the very high level of consciousness of the Jewish People that
prevailed when the Temple existed, we saw ourselves reflected in the sacrifice,
burning up for God, as it were. We experienced nature returning to and
reuniting with its Divine Source.
When we lost this high level of consciousness, the Temple was destroyed,
for we were no longer worthy of it and its Divine service. Nevertheless
our sages teach us that every table at which we eat symbolizes the altar in
the Temple where the sacrifices were burned. Knowing that nowadays our
table is symbolic of the altar of the Temple, and that the food we consume
releases energy in a way similar to a sacrifice adds a powerful new dimension
to our meals. Whenever we eat, we should have in mind that we are raising
the energy of the food in an offering to God, and that we intend to use the
energy that we obtain from the food to serve God.
FIGURE 8.4
Kosher Symbols
Some of the many kosher symbols found in
food labels, informing the consumer that a
rabbinical authority certifies that the labeled
food is kosher. The OU symbol from the
Union of Orthodox Jewish Congregations is
one of the oldest in the United States and
certifies over 300,000 products worldwide.
©Torah Science Foundation
For a Jew, only kosher food truly releases its energy in an optimal manner
conducive to serving God. Only kosher food can raise our level of
consciousness to recognize God’s Presence in our lives and devote our lives to
His service. Maimonides teaches that eating kosher food is the truly healthy
way for a Jew to live (FIGURE 8.4).
The power of will in our soul is likened to fire and expresses our burning
passion to achieve a goal. The sages teach that “nothing stands before (the
force of one’s) will,” and “there is nothing as forceful as will.” Aligning our
will to God’s makes for a healthy soul. God tells us what we may eat and
what we may not. By obeying His will and making His will our will, we
strengthen our souls. A strong soul strengthens the body in which it resides.
There are mammals that are kosher and those that are not. The same goes
for birds, fish, and insects (certain grasshoppers are kosher). In general, those
species that are not kosher display negative characteristics in their lifestyle,
such as cruelty, either in the form of preying on other animals or parasitism.
We do not want to incorporate these negative traits into our systems by
consuming those non-kosher species.
In Hebrew, the language of creation, the word for “life,” or “life force,”
chaim, is related to the word for “heat,” chom. The Ba’al Shem Tov, the great
Jewish leader and founder of the Chassidic movement, used to place his
hand on the heart of a child and bless him: “Be a warm Jew.”
In the Temple, fire would descend from heaven to consume the sacrifices
offered on the altar. Likewise, when eating we should have in mind to
connect with the essence of this holy fire. Connecting to this fire warms the
heart, making it burn with desire to serve God. The Ba’al Shem Tov used
to send his disciples to observe how simple Jews eat with the pure, innate
intention of “burning up” the energy in the food for God.
Torah of Life – An Integrated Torah-biology Textbook
803
A person running a marathon will utilize a significant amount of energy.
Most of that energy will be used to generate ATP, to drive muscle movement.
In addition, proteins are degraded under intense exercise, and there is also
protein synthesis. Ingested food provides the raw material for these processes,
including building blocks needed to repair and rebuild existing tissue.
Besides proteins and their amino acid components, food is the source of
the building blocks needed to manufacture cell membranes and the genetic
material DNA.
Most organisms, however, are limited in their ability to manufacture some
essential building blocks. There are at least 45 substances needed by the
human body that it cannot manufacture on its own. In mammals, these
include eight amino acids needed to build essential proteins that must be
obtained from ingested food. Humans obtain amino acids by breaking
down ingested proteins. Another source of amino acids is the breakdown of
existing body proteins which are in constant turnover, as the tissues of the
body undergo renewal.
©Torah Science Foundation
Mammals are unable to manufacture acetyl groups–C 2H3O (FIGURE 8.5).
The acetyl groups are very common in food and ingested acetyl groups are
found in a large number of different molecules.
The concepts related to food and its metabolism are studied in the science of
nutrition. The studies seek to determine optimal diets and the quality and
quantity of food needed by the body. Nutritionists also plan diets for people
with special needs, such as diabetics.
Nutrients
Nutrients are substances in food that supply the energy and raw materials
your body uses for growth, repair, and maintenance. The nutrients that the
body needs are water, carbohydrates, fats, proteins, vitamins, and minerals.
FIGURE 8.5
The Acetyl Group
Mammals lack the enzymes needed to
synthesize the acetyl chemical group and
must ingest it. The acetyl group is very
abundant in many food sources and used
in many different molecules. It is found in
Vitamin A, in the important intermediary of
respiration, citrate, and many amino acids,
oils, and vitamins. The acetyl group is an
important example of the dependency of
humans on food for their nutritional needs.
Citrate
H2C
COOH
C
COOH
HO
H C
From Food
H
H
O
C
C
C OOH
Amino Acids
Oils
Vitamins
H
Acetyl Group
Carbon Skeleton
H3
C H3
C
CH3
C
C H
CH
C
H2 C
H2 C
C
CH2
C
Vitamin A
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Chapter 08 – Nutrition
C H3
H
C H
C
C
H
C H2OH
C
CH
C
Water
Water is the most important nutrient. At birth, a human baby may be
composed of up to 90% water, with water making up about 70% of an
adult. Most of the chemical reactions in living organisms occur with the
reactants dissolved in water, and water is the universal solvent on earth.
Plant seeds with very low water content can live for centuries in a dormant
stage. Once the seed is hydrated, metabolism is activated, the seed
germinates, and either it is successfully established in a humid environment
or it dies. Terrestrial plants are continuously losing water through the
leaf surfaces in a process called transpiration. On a summer day, leaves of
well-irrigated plants are usually significantly cooler than the surrounding
environment, due to the cooling effects of transpiration. This is because
liquid water absorbs energy when it evaporates at the surface of the leaf, and
it cools it. Without the cooling effect of transpired water, plants growing in
full sunshine would overheat.
©Torah Science Foundation
In mammals, including humans, water loss through sweating plays an
important role in the control of body temperature. Sweat glands remove
water from body tissues and release it as sweat. In a process similar to
leaf transpiration, the water in sweat evaporates, and it cools the body.
Water vapor is also lost from the body during breathing. It is generally
recommended that humans drink between one and two liters of water
per day. If the water lost is not replaced, the body dehydrates, and the
dehydration causes problems with the circulatory, respiratory, and nervous
systems.
Water is linked to the sefirah (our faculty) of wisdom, which is the first
power of the conscious intellect (“revealed mind”). Wisdom manifests in the
soul as flashes of new insight into truths that lie at the core of reality. Like
water, which flows downhill from a high place to a low place, the insights of
our wisdom flow down from their source in our super-conscious “concealed
mind,” and continue to flow downhill to permeate all the conscious powers
of our souls.
Wisdom (water) is referred to as “the point that is present uniformly
throughout the body.” It corresponds to the letter yud (‫)י‬, which resembles a
point, the first letter of the Tetragrammaton (God’s four-letter Name).
Water is the source of life, and the water we drink becomes part of our
life force. In the Torah, spring waters are called “living waters.” Spiritually,
wisdom is the source of life, as in the verse “wisdom gives life,” and so the
study of Torah (Divine wisdom) is also likened to water. In the words of the
sages: “Water refers to the Torah.”
So many different substances dissolve in water that, as we saw earlier, it is
called the universal solvent. Likewise, all secular knowledge dissolves in the
water-wisdom of the Torah. The goal of the Torah is to unite, and in our
generation, our goal is the unification of Torah and science.
Torah of Life – An Integrated Torah-biology Textbook
805
Carbohydrates
Carbohydrates are the main source of energy in food. You may recall that
most carbohydrates have the general chemical formula: Cn (H2O)n. The name
of these compounds means hydrates of carbon.
Simple carbohydrates include glucose and fructose, early products of
photosynthesis in plants that are very common in fruits, honey, and sugar
cane. Complex carbohydrates are large chains (polymers) of simple sugars
(FIGURE 8.6a-c). Starch is a common complex carbohydrate found in grains,
potatoes, and vegetables. Plants store large amounts of glucose and other
simple sugars synthesized by photosynthesis in the starch, which is later found
in storage organs like potatoes, or as reserve food for seeds, such as grains.
When the seeds germinate, they utilize the starch as food to grow in the
early stages of germination, until the seedling is able to photosynthesize and
generate new sugars.
We eat starch when we eat bread, pasta, and potatoes. Starches are broken
down in our digestive system and simple sugars, such as glucose, are released.
The sugars are absorbed by the bloodstream and carried to all cells of the
body. The breakdown of glucose through the process of respiration supplies
readily available energy for all cellular needs.
©Torah Science Foundation
Animals store excess simple sugars in the complex carbohydrate glycogen,
which is abundant in the liver and in skeletal muscle. Like starch, glycogen
is a branched polymer of glucose. Small concentrations of glycogen can be
found in the kidneys, in some glial cells of the brain, and in white blood cells.
Like the starch stored in seeds of plants, the uterus stores glycogen during
pregnancy to nourish the embryo. When we eat a carbohydrate-rich meal
such as pasta, blood glucose increases and glycogen is made in the liver. When
glucose levels drop and energy demand increases, glycogen is broken down
and the glucose from liver glycogen becomes the energy source for the body.
Another important complex carbohydrate that is also a polymer of glucose is
cellulose. Plant cells have walls that are mostly built of cellulose. Cellulose is
the most common organic compound on Earth, and about 33% of all plant
matter is cellulose.
CH2OH
H
O
H
O OH
H
O
H HH
OH
H
OH
OH
H
H
CH2OH
O
CH2OH
HH
H
O
OH
H
O
O
H HH
OH
FIGURE 8.6a
H
OH
OH
H
CH2OH
H
O
H
O
FIGURE 8.6b
FIGURE 8.6c
Complex Carbohydrates
Glucose molecules can link to each other  (FIGURE 8.6a) forming giant polymer chains (Figures 6b and c). Cellulose is made of parallel linear chains
(FIGURE 8.6b). Starch (FIGURE 8.6c) and glycogen (not shown) are made of branched chains.
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Chapter 08 – Nutrition
Can you guess which is the cellulose-made material most common in
your life? The answer is paper.
chesed
gevurah
might
(proteins)
Ruminants, such as cows, digest cellulose with the help of microorganisms that live in their guts. Humans, on the other hand, can digest
cellulose only to a very small extent. However, cellulose is important in our
diet as dietary fiber helping bulk food and waste move through the digestive
system. Foods rich in fiber include whole-grain bread, bran, and many fruits
and vegetables.
What comes to mind when we hear the word “carbohydrate”? Many people
will immediately think of bread. Observant Jews who are about to eat bread
will first wash their hands, say the blessing “al netilat yada’im,” and then
bless the bread with the blessing of “hamotzi.” Only then, the bread is eaten.
hod
tiferet
loving-kindness
(carbohydrates)
beauty
(fats)
acknowledgment
(minerals)
netzach
victory
(vitamins)
FIGURE 8.7
The Five Sefirot
The sefirah of binah is associated with food
and it is connected with the five emotive
sefirot of chesed (carbohydrates), gevurah
(proteins), tiferet (fats), netzach (vitamins),
and hod (minerals).
Besides “hamotzi lechem min ha’aretz,” the blessing for bread, there are other
blessings for different foods. We say “borei minei mezonot” for foods such as
pastry or pasta, “borei pri ha’adama” for vegetables, and “borei pri haetz” for
fruits from trees. However, if we are about to partake of a Shabbat or festive
meal, we first wash our hands and eat bread after the “hamotzi” blessing. The
blessing of the bread will cover all the other foods we eat at that meal, which
we would otherwise bless over separately if we were sitting down to a meal at
which no bread was served.
©Torah Science Foundation
What is unique about bread that makes it the all-inclusive food? The central
role of bread for our forefathers is very clear in the Torah. Malchizedek,
the king of Shalem, welcomed Abraham our father with “bread and wine”
when Abraham returned from his victory over the four allied kings (Genesis
14:18). Abraham offered “a morsel of bread” to the three angels who visited
him in the guise of wayfarers, and he hurried Sarah to knead and make cakes
out of fine flour (Genesis 18:5-6).
We noted earlier that water is associated with the sefirah of wisdom, the
first power of the intellect. Food is associated with the next, complementary
power of the intellect, the sefirah of binah, understanding, which
corresponds to the first hei (‫ )ה‬of the Tetragrammaton. The numerical value
of the letter hei is five. Wisdom and understanding are compared to father
and mother.In the context of our study of nutrition, the father (wisdom)
provides the life-giving water, and the mother (understanding) provides the
five basic nutrients — carbohydrates, proteins, fats, vitamins, and minerals
(FIGURE 8.7). These correspond to the five basic emotions of the soul, already
present within the spiritual womb of understanding. Bread, the primary
source of carbohydrates in our diet, corresponds to the first of our soul’s
emotive attributes, loving-kindness. In the idiom of the Zohar, the classic
text of Kabbalah (the inner dimension of the Torah), loving-kindness is
called the “day” (referring to the first day of Creation) “that accompanies
all days” (the remaining days of the week). The Zohar is teaching that the
light created on the first day illuminates and activates all succeeding stages of
creation. All meals begin with bread and bread accompanies all the portions
of the meal.
Torah of Life – An Integrated Torah-biology Textbook
807
Amino Group H3N+
Val
Arg
Lie
Cys
Glu
Leu
H
O
S
S
Lys
Asn
Cys
Asp
Val
Ser
Tyr
Pro
FIGURE 8.8
Proteins
Proteins are polymers of amino acids.
Amino acids join each other by peptide
bonds between their amino end and their
carboxyl end. 
Leu
Lys
C
+
C
H
O
C
C
H
O
N
C
C
H
CH3
O-
O
H2N
H
Glycine
H
C
O-
Gin
His
Phe
H2N
Ala
O
H
Gly
H
H2N
OCH3
Alanine
H
Peptide Bond between Glycine and Alanine
COO- Carboxyl Group
Thr
As discussed above, we aspire to eat with the consciousness of making
our table an altar, in which the Divine force inherent in food, particularly
bread, is extracted to nourish our body, both physically and spiritually. We
emulate the kohanim, the priests of the Temple, by washing our hands before
approaching the altar, and blessing God, the Giver of the bread, before we
eat it.
©Torah Science Foundation
FIGURE 8.9a
The 20 Common Amino Acids
There are 20 common amino acids, listed in
the table. Proteins can consist of a few to
several thousand amino acids. For example,
hemoglobin, the oxygen carrying blood
protein, has 574 amino acids.
Amino Acid
Abbr.
Alanine
Ala
Arginine
Arg
Asparagine
Asn
Aspartic Acid
Asp
Cysteine
Cys
Glutamine
Gln
Glutamic Acid
Glu
Glycine
Gly
Histidine
His
Isoleucine
Ile
Leucine
Leu
Lysine
Lys
Methionine
Met
Phenylalanine
Phe
Proline
Pro
Serine
Ser
Threonine
Thr
Tryptophan
Trp
Tyrosine
Tyr
Valine
Val
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Chapter 08 – Nutrition
Proteins
Customarily meat is served on joyous occasions. One of the ways in which
meat differs from other foods is its high protein content. Meat is mostly
muscle from an animal, which is usually 75% water and 20% protein
(typically, a pasta dish is less than 10% protein).
You may recall that proteins are polymers of amino acids. In the protein
polymer, the amino group of an amino acid is bonded to the carboxyl group
of the next. There are 20 common, naturally occurring amino acids, and
different combinations of amino acids specify the properties of the hundreds
of thousands of proteins that exist in living organisms (FIGURE 8.8).
Proteins are essential for life, and all enzymes are proteins. Enzymes, such as
proteases and amylases, are needed for protein and carbohydrate digestion.
The protein hemoglobin transports oxygen from the lungs to the rest of
the body, and the protein insulin regulates sugar levels in the blood. The
chloroplast protein rubisco, thought to be the most abundant protein on
Earth, catalyzes the binding of carbon dioxide to one of the Calvin cycle
intermediates that is part of the cycle driving carbon dioxide fixation and
the synthesis of carbohydrates by plants. When a person eats a teaspoon of
honey, the sugar found in the honey will readily enter the bloodstream and
be used as a source of energy. The digestive process with ingested proteins
is very different. Enzymes present in the stomach digest the proteins and
individual amino acids are released. The amino acids reach the blood stream
and are distributed to many cells of the body, where new proteins will be
synthesized following the genetic program of the organism.
Of the 20 common amino acids (FIGURE 8.9a) that the body needs to
synthesize its own proteins, 12 can originate from ingested food or be made
by the metabolic machinery of the body. The other eight are essential amino
acids that the body cannot make and must be ingested (FIGURE 8.9b).
Food sources with complete proteins (containing all the amino acids)
include meat, eggs, milk, and fish, and the milk products yogurt and cheese.
Soybeans are the only vegetable considered to be a source of complete
protein. A combination of legumes with grains, such as beans and rice or
corn, can provide a source of complete protein.
Proteins correspond to the emotive sefirah of might and the inner experience
of fear. When we refer to the sefirot, our frame of reference is the human
soul. What is the connection between the human soul, the sefirot, and the
creation of the universe?
Understanding of these relationships is itself a central purpose of creation.
The Torah teaches us that humans are the pinnacle of the creative process.
This is not meant to make us feel arrogant. On the contrary, the Torah
instructs us to emulate the great Jewish leader, Moses, the humblest man ever
to walk the face of the earth.
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
FIGURE 8.9b
List of eight essential amino acids.
©Torah Science Foundation
God loves us and wants us to love Him and recognize Him as the Master
of the Universe. Why would God, an infinite and all-powerful being, care?
Though we can never really know the answer to this question, we can only
say that God does care, and desires, for our eternal good, that we become
conscious partners with Him to better the world in which we live by first
understanding, to the best of our ability, the purpose behind creation.
Acquisition of a rectified state of consciousness is greatly aided by
understanding the origin of the universe. The Torah teaches us that at the
beginning there was only God, and that He first manifested pure, simple
light. The creative process continued with a progressive attenuation of the
pure, Divine light and its enclosure in material form.
One of the early stages of creation (a continual, ongoing process) is the
manifestation of the vessels of the ten sefirot, and the enclosure of the pure,
Divine light within them. The light corresponds to the soul and the vessels to
the body. In the early stages of creation, the body is totally transparent and
“null” to the soul within it. The only consciousness is that of the soul, the
consciousness that God is one and that there is no other besides Him. The
creative process culminates with the creation of ordinary reality, in which the
Divine soul is completely hidden and the body is fully manifest.
The description of the sefirot as attributes of the human soul reflects the fact
that the human being is a microcosm of the universe. As the vessels of the
sefirot descend from level to level they break the simple, “white” Divine light
into an observable spectrum of colors. The three primary emotions of lovingkindness, might, and beauty — corresponding to the three basic nutrients:
carbohydrates, proteins, and fats — correspond to the artist’s three primary
colors of blue, red, and yellow.
Carbohydrates correspond to loving-kindness and the color blue. Proteins
correspond to might and the color red. Fats correspond to beauty and the
color yellow. (FIGURE 8.10).
We can visualize the red nature of proteins by thinking of red meat or red
lentils (an excellent source of protein). Our patriarch Jacob prepared a red
lentil soup to console his father, Isaac, upon the passing of his grandfather
FIGURE 8.10
The Sefirot and the Colors of the
Spectrum
Each sefirah is associated with a color.
Here we show the relationship between the
three primary emotive sefirot and the three
primary colors: Chesed, loving-kindness
(carbohydrates) is blue; Gevurah, might
(proteins) is red; and Tiferet, beauty (fats)
is yellow.
chesed
gevurah
might
(proteins)
tiferet
loving-kindness
(carbohydrates)
beauty
(fats)
Torah of Life – An Integrated Torah-biology Textbook
809
Abraham. Abraham is associated with loving-kindness (carbohydrates and
the color blue), Isaac with might (proteins and the color red), and Jacob
with beauty (fat and the color yellow). Esau, Jacob’s twin brother, symbolic
of profane might and fear, came tired from the field and asked Jacob to pour
into his mouth “the red, the red,” for which reason Esau became known as
“the red one.”
Why can the human body synthesize only 12 of the common 20 amino
acids, and not the other eight essential amino acids? The Torah teaches that
the universe is comprised of four different kingdoms: the mineral kingdom
(dust and rocks), the vegetable kingdom (plants), the animal kingdom
(animals, fish and insects), and the human kingdom, which the Torah calls
medaber, “the speaker.” This division is hierarchical: the world of dust and
rocks is the lowest level, and the human world (the world of fully developed
consciousness manifested in speech) is the highest.
Humans have a critical role in the unification of the four kingdoms and this
role is connected with nutrition. By extracting the physical nutrients and
spiritual “sparks” from their environment — the lower realms of reality in the
mineral, vegetable, and animal kingdoms — and “ingesting” them, humans
elevate the nutrients and sparks from the lower worlds and transform them
into vital human energy.
©Torah Science Foundation
At the same time, plants and animals have a primordial vital energy that, in
a certain spiritual sense, originates from a source higher than the origin of
the human soul itself! That’s why we humans need to consume plants and
animals to sustain us, and provide us with necessary nutrients, beginning
with the eight essential amino acids that we cannot produce ourselves or
obtain in any other way! In particular, the amino acids we miss are necessary
to make proteins, and indeed it is explained that the superior spiritual
origin of the food we eat in relation to ourselves lies in the sefirah of might,
corresponding to protein.
Fats
Most of us enjoy having a breakfast in the morning that may include a
glass of milk, bread, and butter or margarine. We learned about bread in
the carbohydrates section. What about butter or margarine? They’re fats or
lipids.
You may recall that fats are made of fatty acids and glycerol. Depending on
their chemical structure, fats can be solid or liquid at room temperature. The
oil people use in salads is a liquid fat. Butter, margarine, and other fats are
solid. Fats are a very rich source of energy; one gram of fat contains about
nine calories (a gram of sugar contains less than half of that amount). Fatty
acids are highly reduced and their oxidation generates abundant ATP per
unit of mass. Hibernating animals eat more than usual in the fall and store
the food energy as fat, which they use during the winter.
Glucose levels in the blood are tightly regulated by hormones, such as insulin
and glucagon, which control the metabolism of carbohydrates and fats.
When blood sugar is low, fatty acids are transported to the cells that need
energy, such as muscle cells. The fatty acids are broken down and oxidized
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Chapter 08 – Nutrition
in the cell mitochondria. The oxidation generates ATP that supplies energy
for cellular work. When blood sugar is high, liver and muscle cells store
the surplus glucose as glycogen. If glycogen depots are full and food intake
remains high, fatty acids are made and stored.
In our diet-conscious times, some people try to eliminate fats from their
food, yet fats are very important for our health. Fatty acids, such as linoleic
acid (FIGURE 8.11), are essential nutrients because the metabolic machinery
of the human body cannot manufacture them; essential fatty acids must be
ingested. Some vitamins, such as vitamin A, an important vitamin for night
vision, are fat-soluble and can only be absorbed and transported together
with fats. Linoleic acid and other fatty acids are also essential for the building
of cell membranes and myelin sheaths. Fat tissue insulates the body and
protects critical organs, such as the heart and kidneys.
However, an excess of fat in our diet can have serious consequences,
including obesity, diabetes, and heart disease. You may recall that fatty acids
differ in the number of hydrogen atoms bonded to the chain of carbon
atoms. If every carbon atom in the chain is bonded to two hydrogen atoms,
the fatty acid is called “saturated.” If at least one carbon atom in the chain is
bonded to a single hydrogen atom, and it is bonded to a neighboring carbon
atom by a double bond, the fatty acid is called “unsaturated.” For example,
linoleic acid, mentioned earlier, has 18 carbon atoms and two double
(unsaturated) bonds. Fatty acids with more than one double bond are called
“polyunsaturated.” Nutrition authorities recommend a diet with a maximum
of 30% of calories from fat, with no more than 10% of saturated fats.
©Torah Science Foundation
It is well known that the human body hoards fat. When food intake is
insufficient, the body will mobilize reserve carbohydrates; if this is not
enough, it will use proteins, and only as a last resort, it will use stored fat.
When the need arises, why is it that the body will rather consume muscle
than stored fat? Despite its importance for the understanding of issues such
as obesity, which is reaching near epidemic levels in developed countries,
science has yet to find the reasons and the mechanisms underlying the
hoarding of fat.
We can learn from the Torah about our relationship with fats. Recall that
carbohydrates are associated with the sefirah of loving-kindness. Fats are
associated with the sefirah of beauty (FIGURE 8.7). The inner experience of
beauty is compassion.
FIGURE 8.11
Double Bond
Carboxylic Group
HO
O
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
C
C
C
H
H
H
H
H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
H
Linoleic acid.
The unsaturated fatty acid, linoleic acid, has
18 carbons and two double bonds. Linoleic
acid is an essential fatty acid, that humans
cannot manufacture and must ingest in their
food for their nutritional needs.
Torah of Life – An Integrated Torah-biology Textbook
811
The emotive attribute of compassion can be expressed in two ways — as prayer
(beseeching God to be compassionate to us) and in being compassionate to
others. The sages teach that in order to arouse God’s compassion one should
first express compassion to others. Therefore, it is fitting to give charity to the
poor before praying. Compassion refers not only to the act of giving charity
(an act of loving-kindness), but to the sense of empathy that motivates the
act. To be compassionate is first and foremost to feel the plight of the other
and identify with him. The Ba’al Shem Tov made compassion a pillar of the
Chassidic movement.
What does the Torah teach about fats? A “fat” body in the Torah denotes
a healthy or “well-oiled” body. In today’s Western culture, a slim body is
considered more beautiful, whereas in other cultures, a fat (although not
obese) body is considered more beautiful.
As stated earlier, the health consequences of too much fat can be severe.
Why, then, does the body hoard fat? We learned earlier that fat is a central
component of cell membranes and of myelin sheaths covering the nerves.
Thus fat protects your organs and insulates your body — actions that relate to
“body-care” — beauty and its inner experience of compassion.
©Torah Science Foundation
Storing fat to be used later, when necessary, points to a fundamental affinity
between the body and fat. Storing away something to be used at a later date
relates to the characteristic of patience, a trait that originates in the superconscious level of our soul and manifests in the sefirah of compassion.
It is a common belief (which has been confirmed to a certain extent by
recent scientific studies) that fat people tend to possess a more pleasant
disposition, are more social, and more compassionate to others than are
slim people. This clearly identifies fats with compassion. A pleasant and
compassionate personality is also conducive to good physical health and less
neurosis. (However, modern society can cause people to become neurotic
about being fat.)
People eat (and often overeat) to calm down. But Rabbi Shneur Zalman, the
first Rebbe of Chabad, teaches that the in-depth study of Torah, particularly
Chassidic philosophy, is the best tranquilizer of the soul. So there is no need
to eat in order to relax!
Vitamins
Vitamins are carbon-based, essential organic molecules that are required for
normal growth and metabolism. Like the essential amino acids and fats, most
vitamins must be obtained from food. In contrast to the essential amino
acids and fats, vitamins are needed in very small amounts; a few milligrams
per day will suffice. However, vitamin deficiency can have severe, even fatal
consequences.
Thirteen essential vitamins have been identified in humans, and they can be
divided into two categories: water-soluble and fat-soluble. The water-soluble
vitamins include vitamin C and the B vitamins. Water-soluble vitamins
cannot be stored in the body and must be obtained from food every day.
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Vitamin C deficiency causes scurvy, a disease characterized by bleeding
gums, loss of teeth, and slow wound healing. Before the discovery of vitamin
C, sailors suffered from scurvy during long sea voyages. It was later learned
that scurvy can be prevented by eating fresh vegetables and fruits.
The fat-soluble vitamins include vitamins A, D, E, and K. Vitamin A is a
component of visual pigments, vitamin D facilitates the absorption and
metabolism of calcium and phosphorus, vitamin E is an antioxidant that
prevents damage to cell membranes, and vitamin K facilitates blood clotting.
In contrast to the water-soluble vitamins, the fat-soluble ones accumulate
in body fat, so the stored vitamins can be used when their intake from food
is insufficient. An over-abundance of water-soluble vitamins is excreted in
urine and is generally harmless. On the other hand, an excess of fat-soluble
vitamins remains in the body and can be toxic.
Nutritionists study daily needs of vitamin intake, and the Federal Drug
Administration publishes recommendations for daily allowances. Some
controversies have arisen surrounding these recommendations. For instance,
the recommended daily intake of vitamin C is less than 100 mg, but some
studies claim that a daily intake of 1,000 mg reduces the risk of cancer and
cardiovascular diseases. More data is needed for definitive answers, but it
is clear that a healthy lifestyle and a balanced diet eliminate most risks of
vitamin deficiencies.
©Torah Science Foundation
Minerals
Minerals are simple inorganic nutrients and, like vitamins, are usually
required in small amounts. In plants, the mineral manganese is required for
the photosynthetic reaction that splits water and generates oxygen. Most
of the oxygen in the earth’s atmosphere, which is essential for all aerobic
organisms, including humans, is generated by the manganese-requiring,
water-splitting reaction in photosynthesis. Phosphorous is required for
ATP and nucleic acids. Iron is required by the cytochrome molecules that
function in photosynthesis and in cell respiration, and for hemoglobin, the
oxygen-binding protein of red blood cells. Potassium, sodium, and chloride
are important for the regulation of the osmotic balance between cells and the
outside environment. Humans and other vertebrates require relatively large
amounts of calcium for the building and maintenance of bone.
Excess sodium intake can cause health problems. The maximum
recommended daily sodium intake in humans is 2,300 mg., but many
people may be consuming two to three times that amount. This is because
packaged food may contain high amounts of sodium chloride, even if it
does not taste salty. High sodium intake has been associated with high
blood pressure. Excess iron intake can cause liver damage. As stated earlier,
a balanced diet which includes a variety of foods and sufficient fresh fruits
and vegetables ensures a healthy lifestyle and will supply adequate levels of
required minerals.
Vitamins are associated with the sefirah of victory, and the inner experience
of confidence. Minerals are associated with the sefirah of acknowledgment,
and the inner experience of sincerity. In Kabbalah, confidence and sincerity
are described as two sides of one coin. In the physical domain, vitamins and
Torah of Life – An Integrated Torah-biology Textbook
813
minerals parallel this close relationship: both are essential for a healthy body
and are used in small amounts.
God promised assistance to those who strive to be partners with Him
in creation and dedicate themselves to rectify the world. Recall that fats
are associated with compassion. Psychologically, the fat-soluble vitamins
represent confidence based on the experience of compassion. This sense
of self-confidence arises from our experience of God as always being near,
always expressing His compassion towards us. This self-confidence is
warranted because God is always eager to give us the power to succeed in
achieving our life goals. Here too, the physical plane mirrors the spiritual/
psychological plane, because excessive amounts of the fat-soluble vitamins,
just like over self-confidence, can be toxic.
In contrast, water-soluble vitamins must be obtained every day. On the
spiritual plane, they represent total reliance and confidence in God, our
Father in Heaven (note that water corresponds to wisdom, also known as the
father principle, as mentioned above). The water-soluble vitamins nurture
confidence that God will provide us with our needs every day.
©Torah Science Foundation
Sincerity implies simplicity, which in our context, alludes to simple,
inorganic chemical elements necessary for our bodies to function properly.
Like vitamins and minerals, confidence and sincerity function together
as two partners, and in Kabbalah, they are depicted as two legs,neither of
which, when walking, can function without the other.
Nutrition and a Balanced Diet
A healthy diet involves consuming appropriate amounts of all nutrients,
and an adequate amount of water. Nutrients can be obtained from many
different foods, so there are a wide variety of diets that may be considered
healthy diets. A healthy diet needs to have a balance of carbohydrates,
proteins, and fats, and adequate amounts of vitamins and minerals.
You should eat a variety of foods each day and limit your intake of fatty,
sugary foods. Read food labels before making your purchases so that you
can choose healthful foods. A food label provides some general information
about nutrition, listing the daily values and the calories per gram of
carbohydrates, protein, and fats. The daily value shows you how the
particular food fits into the overall diet. Keep in mind that daily values are
based on a 2,000-calorie diet.
Nutritional needs are affected by age, gender, and lifestyle. Rapidly growing
adolescents and other groups of people need more nutrients than the daily
values indicate. When choosing foods, you should use the information on
food labels to compare with similar foods on the basis of their proportion of
nutrients to calories. A desired food should be high in nutrition and low in
calories.
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Let us now see how the basic rules for a healthy physical diet translate into
guidelines for a healthy spiritual life. As discussed earlier, foods rich in
complex carbohydrates represent the emotive attribute of love for both God
and mankind. Love is the first of the five emotions initially contained within
understanding, inspired in the intellect. Just as complex carbohydrates are the
basis of our physical diet, intellectually inspired love, derived from in-depth
study of the Torah and meditative prayer, forms the basis of a healthy spiritual
life.
You should limit your intake of fatty, sugary foods. Likewise, in the spiritual
sphere, too much unregulated love (sugary foods) or compassion (fats) on
yourself may have a negative influence on your overall well-being.
As explained above, the energy released from the food that we eat will help us
mature in character and ascend in our service of God. A Jew should strive to
eat kosher food according to the laws of the Torah.
A healthy body requires a healthy soul — the two are totally interdependent.
In Hebrew, the initials of “body” (guf) and “soul” (neshamah) spell the word
for “garden” (gan). A well balanced diet, together with proper, Divinely
oriented consciousness, brings us back to the unadulterated state of the
Garden of Eden, where God placed us before we committed the primordial
sin of eating that which God had forbidden. Just as mankind was exiled from
the Edenic state because of choosing to eat unwisely, so our return to the
Edenic state depends on rectifying our most basic drive — our need to eat.
©Torah Science Foundation
Torah of Life – An Integrated Torah-biology Textbook
815
Chapter 15
The
Nervous System
IN THIS CHAPTER
• The Nervous System
• The Nerve Impulse
• The Synapse
• Anatomy of the Brain
• The Peripheral Nervous System
Thermostat in
hypothalamus
activates
warming mechanisms
Increased body
temperature
Internal body temperature
of approximately 37°C
Thermostat in
hypothalamus
activates
cooling mechanisms
Body temperature
decreases
FIGURE 15.1
Thalamus
Hypothalamus
1700
Chapter 08 – Nutrition
Feedback Loops
The function of the hypothalamus in the feedback regulation
of temperature in the human body.
Torah of Life – An Integrated Torah-biology Textbook
The need to maintain a stable, controlled environment within the body is
crucial to the overall functioning of the different organs, and the human
body as a whole. Homeostasis refers to the ability of the human body to keep
internal conditions in balance in the face of constantly fluctuating external
environmental conditions.
Consider a thermostat, which regulates the temperature of a room. It
operates on similar principles as the homeostatic mechanisms of the human
body by regulating environmental conditions. The thermostat’s sensor gets
triggered to activate the heating system when the temperature drops below
a certain set point. Similarly, when the temperature in the room rises above
this set point, the thermostat’s sensor is triggered again, but this time to turn
off the heating system. In this way, the thermostat maintains the temperature
of the room within a tight range.
The operation of the thermostat creates a feedback mechanism between
three entities— the thermostat, the temperature of the room, and the heating
system. The feedback mechanism operates as a negative feedback loop that
acts on the principle of feedback inhibition, in which a stimulus initiates a
response that opposes the original stimulus. The stimulus, in this case the
elevated temperature of the room, initiates an opposite response (turning the
heating system off) to the original stimulus (cool room temperature).
©Torah Science Foundation
The human body is also capable of achieving homeostasis through the
mechanism of feedback inhibition (Figure 15.1). The body’s systems are able
to regulate the cellular environment and respond to feedback from these
activities by switching the systems on or off, depending on the need. To
achieve this, all organ systems must be integrated with one another.
For example, regulating body temperature has a lot in common with the
example given above of the thermostat regulating the temperature in a room.
In this case, the brain’s hypothalamus monitors the internal temperature
of the body’s organs, as well as the temperature of the skin at the body’s
surface. The hypothalamus is a small region of the brain that controls various
functions in the body, including temperature regulation, food and water
intake, the sleep-wake cycle, and endocrine, autonomic and motor functions.
Without homeostasis, people (and living organisms in general) could not
survive for long. External changes, often extreme or even violent, would
disrupt the equilibrium of the system to the extent that it would collapse and
break down.
This is exactly what happened in the primordial form of Creation (called
Tohu— the World of Chaos) that preceded the creation of the world as we
know it. It is referred to briefly in the second verse of Genesis: “And the
world was without form (Tohu) and equilibrium.” As a result it disintegrated,
so that each of its seven “kings” ruled for only a very short period of time
and died (Genesis 36:31 ff.). Each king represents an era of domination by
a single unbalanced emotional attribute. As soon as each attribute assumed
kingship, it lost balance (was unable to maintain homeostasis) and collapsed.
Torah of Life – An Integrated Torah-biology Textbook 1701
Our psychological and spiritual makeup parallels our physical makeup.
In order to thrive and fulfill our purpose in life, we must maintain
psychological and spiritual homeostasis; we must stabilize our spirits (the
fluctuations that take place in our soul). We must maintain our emotional
highs and lows within reasonable boundaries (just as body temperature
should stay around 37°C), lest we become bipolar (“mood swings” between
mania and depression) and trigger a nervous breakdown (as was the fate of
the primordial kings of the World of Chaos).
How do we maintain this homeostasis? By fulfilling the first precept of
Jewish Law: “Place God before you always.” The Ba’al Shem Tov (the
founder of the Chassidic movement) called this “the law of equanimity.”
It is the ability to maintain spiritual equilibrium amidst changes (even
drastic changes) in the world around you, and across an enormous range of
conflicting emotions. This ability stems from the fact that all life-experiences
derive from and reflect one constant Cause, “The Cause of all causes,” God,
the absolutely good Creator of the universe.
©Torah Science Foundation
The great Rabbi Levi Yitzchak of Berditchev would often sing to God:
“Above – You! Below – You! East – You! West – You! North – You! South –
You! If it’s good – You, and if not – also You! And if it’s You, it’s good! You,
You, You, all is You!” That is the secret of spiritual homeostasis, even for one
that soars up to Heaven (to bring God down to earth) and descends to Hell
(to redeem lost souls).
Spiritual homeostasis must be an integral aspect of our lives. The Talmud
tells of one extreme example of a lack of spiritual homeostasis. It tells of the
four sages who attempted to rectify the primordial sin of Adam and Eve
and entered the “Pardes” (also known as the “Orchard,” a metaphor for the
mysteries of Creation and Godliness that are revealed in higher planes of
reality, the “higher worlds” in Kabbalah). They were Rabbi Akiva, Ben Azai,
Ben Zoma, and Elisha Acher. Ben Azai died, Ben Zoma went insane, and
Elisha Acher became a heretic.
Only Rabbi Akiva entered in peace and came out in peace. Only he was able
to maintain spiritual homeostasis (a state of inner equilibrium and peace)
because he possessed a feedback inhibition control system! His heart began
soaring up to Heaven to enter the Pardes, gaining energy and spiritual heat
(passion and fervor) from moment to moment. He could have expired in
ecstasy when he reached the epitome of Divine revelation that his soul was
capable of conceiving. But at that exact moment of spiritual danger, his heart
told him to return to his earthbound reality (this being the true desire of
God). The other three sages lacked this feedback inhibition.
We also note a lack of feedback inhibition in the Biblical story of Nadav and
Avihu, the two sons of Aaron the High Priest. Nadav and Avihu died in a
fiery run upward to God, not knowing at what moment to return, and not
desiring to return.
A story illustrating the same point is also told about Rabbi Avraham, the
son of the Magid of Mezritch, nicknamed the “Malach” (angel) because of
his ecstatic worship. One time he was studying with his close friend, Rabbi
Shneur Zalman (the first Rebbe of Chabad), and he reached such a state of
1702 Chapter 08 – Nutrition
spiritual ecstasy that he was about to expire. Rabbi Shneur Zalman sensed
this and immediately stuck a piece of bagel in his mouth, bringing him out
of his ecstatic state and back down into mundane reality.
Usually, the body’s core temperature is higher than that of the skin. In
response to a drop in core body temperature below 37°C, the hypothalamus
releases chemicals that instruct the cells of the body to increase their
activities, thereby producing additional heat and raising the core body
temperature back to the set point. When the hypothalamus detects this
rise in body temperature, it ceases production of the chemicals, thereby
preventing a temperature rise beyond the set point. As with the example
of the thermostat and heating system, the human body utilizes a negative
feedback loop to keep body temperature in balance.
Other mechanisms that the body uses to maintain temperature homeostasis
include the shivering response in cold weather, and the sweating response in
hot weather. When the core body temperature drops below its normal range,
the hypothalamus releases chemicals that cause the involuntary contractions
of the muscles below the skin’s surface (shivering response). This response
produces heat, which raises the body temperature.
©Torah Science Foundation
Similarly, sweating in hot weather is the result of the hypothalamus
triggering sweat glands to produce sweat, which, through evaporation at
the skin’s surface, helps cool the body down. The return of the body’s core
temperature back to the normal range provides feedback inhibition to the
hypothalamus to stop the sweating response.
The temperature of the body’s core is the temperature of the heart, which is
naturally higher than that of the skin. The Zohar states that the heart may
be pulsating and alive (generating heat) even when the pulse of the wrist is
dead (cold). This was the state of the eighth primordial king of the World of
Chaos, Hadar, who in the Torah (the Five Books of Moses) is said to have
reigned but not to have died (as is explicitly stated of the previous seven
kings). But in Chronicles (written by Ezra the Scribe) he is said to have died.
The Zohar explains the discrepancy: Moses measured Hadar’s heart pulse and
in his core he was alive, but Ezra measured his wrist pulse and there he was
dead.
The Ba’al Shem Tov continuously trembled (shivered). The airwaves
produced by his trembling would even reach a glass of water situated on the
other side of the room and the water would begin to quiver as well. Anyone
who would touch the Ba’al Shem Tov while he was praying would start
shuddering violently.
In the service of God, love raises one’s bodily temperature (a physical
phenomenon that can be measured) and fear reduces it (as in the expression
“shivering with fear”). The Ba’al Shem Tov loved God and feared Him above
our capability to comprehend. He is best known for his love of God, of
Israel, and of all of God’s creations, but in his Divine service his fear of God
exceeded his love, and so he shivered!
Torah of Life – An Integrated Torah-biology Textbook 1703
Every night before sleep, we give
our tired and worn-out souls
back to God. Every morning, we
receive our soul anew, refreshed
and full of energy. Therefore,
the first words that we say upon
awakening are:
“I thank You, ever
living King, for
compassionately
returning my soul
to me; how great is
Your faithfulness.”
The concept of homeostasis applies in a planetary sense as well— in terms
of the multi-year cycles of global warming and cooling— and indeed the
survival of the planet depends on maintaining homeostasis, just as the health
of a person does. Moreover, the Torah teaches us that man’s actions on a
spiritual plane also affect this delicate earth eco-system, as the verse states:
“All the wild shrubs did not yet exist on the earth, and all the wild plants had
not yet sprouted. This was because God had not brought rain on the earth,
and there was no man to work the soil” (Genesis 2:5).
The classic commentator Rashi explains that there was as yet no “rain on the
earth” because “there was no man to work the soil”— there was no one who
recognized the goodness of rain until Adam came along. Realizing that rain
is a necessity for the world, Adam prayed for rain and when it came down,
the vegetation sprouted.
Furthermore, the homeostasis of the world depends on our actions and good
deeds, and this is one of the interpretations of the Mishnah (Sanhedrin 4:5):
“A person is obligated to say, ‘The world was created for my sake.’” In other
words, the continued existence of the world depends upon our actions.
©Torah Science Foundation
The macrocosms— the earth, the planets, and the universe, and the
microcosms— the human being, the cells, the molecules, and the atoms,
are all part of God. In the human being, the soul and the body are united
and pulsate together. Science has no tools to describe the soul, but a unified
Torah-science discourse brings the soul and the body together in a precise
and harmonious way.
The Soul
The soul is eternal and a part of God. The soul experiences our body and the
physical world around us, and at the same time, experiences God.
The great Torah scholar, Maimonides, taught that nothing could be said
about the essence of God. We are commanded to believe in His existence (as
the Creator of the universe) and that He is absolutely one. The Ba’al Shem
Tov made a revolutionary conceptual leap when he taught that because God
is one, and the Divine soul is an “actual part of God,” by contemplating the
essence of the soul (in its service of God), we in fact gain a glimpse of the
essence of God.
The soul is in a continual cycle of “running and returning.” It soars upwards,
seeking to become one with its Creator, and it comes back down to earth,
entrusted with the mission of making a dwelling place for the Creator in this
world. The heartbeat in the body is the harmonic response to this “running
and returning” of the soul, which extends via the bloodstream to the pulse in
the wrist.
In the Bible, the soul is referred to by five names, each reflecting a different
dimension of the Divine character of the human being.
• The nefesh (psyche) resides primarily in the liver.
• The ruach (spirit) resides primarily in the heart.
1704 Chapter 08 – Nutrition
FIGURE 15.2
• The neshamah (the soul proper) resides primarily in the brain.
• The chayah (the living one) resides in the space between the skull and
the brain.
• The yechidah hovers outside the body, above the head.
The Central Nervous System and the
Peripheral Nervous System
The CNS is comprised of the brain and the
spinal cord. The PNS connects the CNS to
the organs, glands, and limbs.
The nefesh connects to the rest of the body through the lymphatic system,
the ruach through the circulatory system, the neshamah through the nervous
system, the chayah through the respiratory system, and the yechidah through
the belief system of the soul.
The Nervous System
The brain, the spinal cord, and the peripheral nerves make up the nervous
system. This system coordinates and controls bodily functions by detecting
and responding to internal and external messages. The building blocks of
the nervous system are the nerve cells, called neurons, and the supporting
cells, called glia. Glial cells play a role in both structural support and in the
development and function of the nervous system, and are discussed in more
detail below.
©Torah Science Foundation
There are three stages of information flow in the nervous system: a) sensory
input via the five senses (sight, hearing, touch, taste, and smell), and
from internal conditions of the organs, such as blood pressure and carbon
dioxide levels; b) integration of these stimuli in the brain; c) motor output
via the muscles and glands. The part of the nervous system that processes
information and signals the responses to these stimuli is called the Central
Nervous System (CNS) (Figure 15.2).
The sensory input via the senses and the motor output via the muscles and
glands is the function of the Peripheral Nervous System (PNS). Both of these
functions are discussed in detail later in the chapter.
Information Flux through Neurons
Neurons transmit tiny electrical signals, called impulses, through the nervous
system to convey information the brain sends and receives. The human brain
is estimated to contain 1011 (that’s 100 billion) neurons.
Neurons are usually classified into three types, based on the direction
traveled by the message they carry. Sensory neurons carry messages from the
sense organs to the spinal cord and the brain. Motor neurons carry impulses
from the brain and spinal cord to the muscles and glands. Interneurons
coordinate higher brain functions, mediate simple reflexes, and integrate and
connect impulses from the sensory and motor neurons.
Although they can come in numerous shapes and sizes, all neurons have the
same basic structure (Figure 15.3). All neurons have a cell body, also called
a soma, where most of the metabolic activity takes place. The cell body
contains a nucleus and most of the cytoplasm of the cell.
Central Nervous System
Brain
Spinal Cord
Peripheral
Nervous System
Body Nerves
Spinal Nerves
Organs
Extending out from the cell body are short, branched structures called
Torah of Life – An Integrated Torah-biology Textbook 1705
FIGURE 15.3
Cell Body
Dendrites
Axon Terminals
Nucleus
Myelin Sheath
Nodes
Axon
The Neuron
All neurons have a cell body with a nucleus
and other organelles enclosed in the
cytoplasm. The dendrites are extensions
of the cell body that receive signals and
communicate them to the cell body. The
axon is a long extension of the cell body
covered with myelin that carries the nerve
impulses away from the cell body. Gaps in
the myelin expose the axon and facilitate the
rapid conduction of the nerve impulse along
the axon.
©Torah Science Foundation
dendrites (from the Greek dendron, meaning “tree”). They receive signals
from other neurons and from the environment. Also extending out from the
cell body is the axon, a much longer extension with a different function— to
transmit impulses from the cell body to other cells or neurons.
Although they are microscopic in diameter, axons may extend several feet in
length. The longest axons in the human body are those of the sciatic nerve,
which run from the base of the spine to the big toe of each foot.
Neurons may have multiple dendrites but have only one axon. Axons may
branch many times before terminating. The axon ends in small branching
filaments called axon terminals.
Bundles of neurons with their dendrites and axons form nerves. Some nerves
consist of only a few neurons; others comprise hundreds or even thousands of
neurons. Both axons and dendrites form special contact points called synapses
(sing. synapse), where information between nerves is transferred through a
series of electrical and chemical changes.
Axons are usually enclosed by an insulating membrane known as the myelin
sheath, which is produced by specialized glia called oligodendrocytes and
Schwann cells. Oligodendrocytes produce myelin in the CNS, and Schwann
cells produce myelin in the PNS.
The gaps between the myelin sheaths, where the axon is exposed, are called
the Nodes of Ranvier. As an impulse moves along the axon, it jumps from
node to node, by a process called saltatory (“jumping,” from the Latin
saltare, meaning “to jump”) conduction. This process results in a cascade of
depolarizations and action potentials that increase the speed at which the
impulse travels along the axon.
Transmission of the Nerve Impulse
Please recall that information travels through the nervous system as tiny
electrical signals called impulses, similar to the way electricity passes
through a wire. However, electric signals within the body are generated
electrochemically— by chemical “ion pumps” rather than by a mechanical
1706 Chapter 08 – Nutrition
generator. An ion is an atom or molecule in which the total number of
electrons is not equal to the total number of protons, giving the molecule a
net positive (more protons) or negative (more electrons) electrical charge. We
will soon examine how these ion pumps work.
Na+
Na+
Na+
Na+
Na+
Na+
de
Outsi
Resting Potential
When a neuron is not transmitting an impulse, we say that it is “at rest.”
When at rest, the inside of the cell maintains a net negative charge, while the
outside of the cell has a net positive charge.
K+
K+
Cell Membrane
l
of C e l
e of C
Insid
Why is there a difference in electrical charge between the inside and outside
of the cell? In part, because the cell membranes are selectively permeable,
meaning they allow the passage of some molecules while preventing others
from entering or leaving the cell. This causes a difference in the sum of
electrical charges inside and outside of the cell. The outside of the cell has an
excess of sodium ions (Na+), whereas the inside of the cell contains an excess
of potassium ions (K+), together with negatively charged protein and nucleic
acid molecules. This results in an overall negative electrical charge.
Na+
Na+
K+
K+
ell
Sodium-potassium
Pump
K+
K+
K+
K+
K+
Na+
ATP
K+
K+
FIGURE 15.4
The Sodium — Potassium Pump
A protein pump in the neuron cell membrane
pumps sodium out of the cell and potassium
into the cell using ATP as the energy source.
©Torah Science Foundation
But the primary reason that the cell carries an overall negative charge is
because of a process known as active transport. In this process the cell
actively “pumps” Na+ out of the cell and K+ into the cell via the sodiumpotassium pump, which is a protein located in the plasma membrane
(Figure 15.4).
One of the important functions of the sodium-potassium pump is to help
maintain the resting potential. When the neuron is inactive and polarized
(i.e., it carries an overall negative charge relative to the charge outside of
the cell), it is at its resting potential, and this is the way it remains until the
neuron responds to a stimulus.
Of course, this does not mean that the cell is inactive at the resting potential
stage; among other things, it is constantly producing adenosine triphosphate
(ATP), which provides the chemical energy needed for active transport
(Figure 8.2 from Chapter 8). ATP contains the four basic elements upon
which all organic life depends— carbon (C), hydrogen (H), nitrogen (N),
and oxygen (O). Its chemical formula is C10H16N5O13P3.
FIGURE 8.2
ATP, Adenosine triphosphate
ATP is a chemical compound consisting of the nucleotide
adenine, the five-carbon sugar, ribose, and three
phosphate groups. The breaking of the chemical bond
between the second and third phosphate group releases a
relatively large amount of energy that is used by the cell to
fuel many energy-requiring processes.
Adenine
ATP
NH2
C
N
C
C
C
Energy Rich Bond
N
C
H
N
Adenosine triphosphate C10H16N5O13P3
N
H
O H
H2C
O
Ribose C
H
H
C
H
C
C
H
OH
OH
O
P
O
O H
O
P
O
O H
O
P
O
H
O
Phosphate Groups
Torah of Life – An Integrated Torah-biology Textbook 1707
Rest is thus not a passive state but a state in which the neuron actively
orients itself with respect to positive and negative electric charges along its
membrane. Similarly, Shabbat as the day of rest is not in essence a passive
state, but one in which a person elevates the active states of the past week,
and orients the coming week in a positive direction, yet in a “restful,” nonactive manner.
In Kabbalah, a positive charge (more protons than electrons) is called
feminine energy, whereas a negative charge (more electrons than protons) is
called masculine energy. In the neuron, the male energy is inside the cell and
the female energy is outside. On the spiritual plane, masculine energy is love,
while feminine energy is awe.
The myelin sheaths that cover the neuron’s axon are membranes rich in
essential fatty acids, which in the spiritual plane derive from the power of
compassion (tiferet). Compassion is what defines and regulates the malefemale interactions, in our case the inside and the outside of a neuron cell
at rest.
©Torah Science Foundation
God created the world with the attribute of severe justice and instructed
humanity to keep the Torah and to fulfill its precepts in order to live. Initially,
He didn’t allow for a second chance. But the Almighty saw that humans
are prone to fall. And so He began ruling the world with the attribute of
compassion and brought teshuvah (repentance and return) to humanity.
Complete repentance and return bring redemption to the world.
In modern Hebrew, the mysterious word chashmal means “electricity.” The
Ba’al Shem Tov elucidated the inner meaning of the word chashmal as a
simultaneous, paradoxical state of silence (chash) and speech (mal). In other
words, chashmal means a simultaneous state of concealment and revelation.
The word chashmal appears only in one context in the Bible, in Ezekiel’s
vision of the Divine Chariot (considered the deepest mystery of the Torah).
Chash, silence, is the inner silence required to face and know reality as it is.
Mal, speech, is the sweetening, unifying process, which, after recognizing
essential distinctions between things, brings different aspects of reality
together.
ATP provides the energy for the sodium-potassium pump. ATP is the
molecule that acts as the “currency” for energy transfer throughout the body.
The formula of ATP (C10H16N5O13P3) includes the four elements (hydrogen,
carbon, nitrogen, and oxygen) that represent the four basic elements of
creation in the classical understanding of the physical world.
H, hydrogen, the main component of water, represents the liquid state of
matter and the sefirah of chesed, loving-kindness. C, carbon, represents
fire, the state of active combustion, and the sefirah of gevurah, might. N,
nitrogen, represents earth, the solid state of matter, and the sefirah of malchut,
kingdom. O, oxygen, represents air, the gaseous state of matter, and the sefirah
of tiferet, beauty. The atomic numbers of these four elements are 1, 6, 7, and
8, which total 22 (meaning that they include 22 protons and 22 electrons),
alluding to the 22 letters of the Hebrew alphabet, the building blocks of
creation according to Kabbalah.
1708 Chapter 08 – Nutrition
The Traveling Impulse
Stronger Depolarizing Stimulus
Similar to other cell types, the cell membrane of a neuron contains
numerous types of ion channels, which are protein structures embedded in
the membrane that can allow passage of specific types of ions.
Some ion channels are chemically gated. A chemically gated channel is one
that is activated by a specific ion (e.g., a potassium ion). Other channels
are voltage-gated (they are activated by changes in electrical charge). The
sodium-potassium pump mentioned earlier is voltage-gated, which means
that both sodium and potassium channels are opened by changes in the
electrical charge of the membrane.
+50
Action Potential
Membrane Potential (mV)
When a neuron receives a large enough stimulus via its dendrites, the
stimulus causes a nerve impulse to travel down the axon away from the
cell body towards the axon terminals. Because the nerve impulse is a very
small electric signal, it causes a reversal of the electrical charges between the
interior and exterior of the cell as it travels down the axon. How does this
happen?
0
Threshold
-50
Resting
Potential
-100
0
3
6
Time (msec)
©Torah Science Foundation
This is how it works: Axons transmit electrical impulses called action
potentials, which are the result of a rapid rise and then fall in the electrical
potential of the axon’s membrane (Figure 15.5). An action potential begins at
the cell body when sodium channel gates open to allow a flow of positively
charged Na+ ions to rush into the cell, establishing a new equilibrium in a
matter of a millisecond.
FIGURE 15.5
The Action Potential
A strong depolarizing stimulus reaches the
threshold and triggers an action potential.
The voltage of the inner membrane changes from a negative charge of
about -70 mV to a positive charge of approximately +30 mV. This switch in
membrane potential triggers the opening of K+ channels, causing K+ ions to
rush out of the cell at almost the same speed as the inward flow of Na+ ions.
As a result, the charge of the inner membrane returns to its original negative
resting potential state. The neuron is once again negatively charged inside the
cell membrane and positively charged outside. The action potential of most
neurons is of very short duration, only about one to two milliseconds. Note
that each channel responds independently and sequentially: Na+ channels
open before K+ channels.
A nerve impulse is self-propagating. This means that an impulse (an action
potential) automatically triggers the neighboring membrane area into
producing an action potential, thus moving the impulse along the axon.
One amazing feature of neurons is that after a very short period of rest
known as the refractory period, the membrane restores its ability to respond
to and propagate the next action potential. The refractory period results from
the fact that the Na+ channels enter a brief state of inactivation after they
close back up, following an action potential.
Insulation of Axons
As mentioned previously, the myelin sheath is organized in such a way that
it leaves gaps at regular intervals along the axon (Figure 15.3). The Na+ and
K+ channels are concentrated in the exposed areas of the axon (unmyelinated
Torah of Life – An Integrated Torah-biology Textbook 1709
areas) in a way that propagates the action potential as it skips along the axon.
This speeds up transmission of the action potential tremendously, to a rate as
fast as 100 meters per second.
The Action Potential
An action potential only occurs when a stimulus is powerful enough to cause
the neuron to transmit an impulse (Figure 15.5). The minimum stimulus
required to cause enough sodium ions to rush into the cell to sufficiently
depolarize the membrane is called the threshold level. If the stimulus is
not powerful enough to open the sodium gates in the membrane, then no
impulse is produced. This follows an all-or-nothing principle, meaning that
an action potential either occurs in response to a sufficiently large stimulus
(or a summation of smaller stimuli), or it does not, if the stimulus is not
strong enough to cause the sodium channels to open.
Action potentials always have the same intensity and are never reduced by
the length of the axon. However, a stronger stimulus will cause more action
potentials to travel along the axon. Some very efficient axons can propagate
action potentials at a frequency of up to 1,000 times per second.
©Torah Science Foundation
The Shabbat is unique because it does not involve impulsive activity. Before
the onset of Shabbat one is instructed to enter a state of consciousness
defined by the sages as “All your work is completed.” And so, on Shabbat,
one avoids the psychologically negative state of impulsiveness.
A threshold is achieved by reaching a critical mass. It takes critical mass to
begin a chain reaction (a snowball effect) that will bring about a significant
change in the state of any system. This is true from the microscopic world to
the macroscopic world, from particle physics to astrophysics, from biology to
psychology to politics.
Revolutions take place when the populace reaches a critical mass of
opposition to the existing regime. It all depends on the stimulus. Similarly
in our spiritual endeavors, our teachers attempt to stimulate our curiosity
by offering interesting insights and observations, in the hope that we will
go beyond the threshold level, and become fully involved and productive
members of our communities.
In the rest state, the negatively charged state inside the cell is masculine,
and the positively charged state outside the cell is feminine. These attributes
are standard, like those that allow us to recognize a baby boy from a baby
girl. The masculine and feminine states are separated by the cell membrane.
When a nerve impulse is triggered, it psychologically translates into a burst
of feminine energy, which is associated with an action potential.
The Synapse
As we explained earlier, the axon ends in an axon terminal (Figure 15.5).
When an impulse reaches the neuron’s axon terminal it may be passed on to
another neuron, muscle cell, or gland cell. The small junction across which a
nerve impulse may pass is called a synapse.
1710 Chapter 08 – Nutrition
A synaptic cleft (Figure 15.6) separates an axon or dendrite terminal from
an adjacent neuron or other cell. The transmitting neuron is often called
the presynaptic neuron because it comes before (pre-) the synapse, while the
receiving cell is called the postsynaptic cell because it comes after (post-) the
synapse.
There are two types of synapses, both of which are found in humans:
chemical synapses (Figure 15.6) and electrical synapses. In chemical synapses,
the impulse reaches the axon terminal of the transmitting neuron and causes
vesicles (small chemical storage sacs) in the axon to release a chemical known
as a neurotransmitter into the synaptic cleft. These neurotransmitters bind
to receptors on the membrane of the receiving cell. This stimulates the
membrane of the receiving cell, causing Na+ ions to flow quickly into the
receiving cell, reversing the resting potential of that cell.
If the stimulus exceeds the receiving cell’s threshold, an impulse begins in
the receiving cell and moves down the receiving cell’s axon as described
previously. Once the neurotransmitters are no longer necessary, they are
released by the receptors and are then recycled by the axon terminal or are
broken down by special enzymes. The vast majority of synapses in humans
are of this type.
©Torah Science Foundation
The neurotransmitters are capable of traversing the abyss of “nothingness”
between “something” and “something,” and convey the desired message from
one state of being to the other. They are “messenger” particles, force carriers.
After binding to their receptors in the receiving, second “something,” they
are released from the cell surface (they do not enter into the second cell) and
are either broken down by enzymes or taken up and recycled by the axon
terminal of the first “something.”
Neuron
Axon
Axon
r
The ultimate sense of serenity experienced by the Divine soul is a sense
of true “nothingness.” The animal soul of the human being experiences
pleasure as “something,” while the Divine soul experiences pleasure as
“nothingness.” The pleasure of experiencing the Divine source of all reality,
the Divine “nothing” from which all “something” has been created, makes us
feel truly humble and reduces our own sense of self to “nothing.”
The Chemical Synapse
Neurons can signal each other through
chemical synapses. An electrical impulse
traveling along an axon reaches a synapse,
the area at which two neurons contact each
other. The gap between the two neurons is
called the synaptic cleft. When an impulse
reaches the axon terminal of a transmitting
neuron, neurotransmitter vesicles are
released and the neurotransmitter binds a
receptor in the other neuron.
ct
In Kabbalistic terminology, the synaptic cleft represents the state of nonbeing (“nothingness”) between two states of being. If each neuron is
considered a “something,” then the synaptic cleft between them is the
“nothing” between two “somethings.” It is the “nothing” that allows for
the transmission of energy (in our case, impulse) from one “something” to
another (from neuron to neuron, or from neuron to muscle tissue).
FIGURE 15.6
ic
m
al I
es
puls Neurotransmitter
Molecules
Ele
In electrical synapses, the pre-synaptic and postsynaptic cell membranes are
connected by pore-like channels that conduct the impulse electrically. They
are quite rare in humans, but some are found in the heart, the eye, and the
brain. The synaptic gap in electrical synapses is far narrower than in chemical
synapses.
Axon
Terminal
Receptor
Synaptic
Cleft
Dendrite &
Neighboring Cell
Torah of Life – An Integrated Torah-biology Textbook 1711
The Central and Peripheral Nervous Systems
As mentioned earlier in the chapter, there are two primary networks within
the nervous system: the Central Nervous System (CNS) and the Peripheral
Nervous System (PNS). The CNS processes and analyzes information
and signals a response (Figure 15.2). The PNS receives sensory input and
connects the CNS to the organs, glands, and limbs.
The Central Nervous System
The brain and the spinal cord comprise the CNS (Figure 15.2). The skull
encloses the brain and protects it from injury. Similarly, the vertebrae of the
spinal column protect the spinal cord from harm. The brain and the spinal
cord are further protected by three layers of meninges (sing. meninx) which
are membranes that envelop the CNS (Figure 15.7a). The three layers are the
dura mater, arachnoid mater, and pia mater. Inflammation of the meninges
is called meningitis, a dangerous and potentially fatal disease.
©Torah Science Foundation
Cerebrospinal fluid flows around the brain and spinal cord, and within the
brain cavities. It delivers nutrients to the brain and spinal cord and detoxifies
the environment of the CNS by disposing of waste products. In addition,
the cerebrospinal fluid provides cushioning support to both the brain and
the spinal cord, and protects the brain from trauma within the skull.
The relationship of the Central Nervous System (CNS) and the Peripheral
Nervous System (PNS) is like that of a king and a servant. The servant
receives information from the outside world and conveys the information
to the king, who then processes and analyzes it, makes decisions, and
commands his subjects. The commands are relayed to the subjects by the
servant.
In democratic systems typical of our times, power is shared and allocated to
different segments of society. The CNS could not function following such
democratic principles. Societies adopt democratic systems when they feel the
need to allow for different, often conflicting values and goals to co-exist. In
a
Skull
b
c
Parietal Lobe
Longitudinal Fissure
Dura Mater
Arachnoid
Pia Mater
Left
Hemisphere
Frontal Lobe
Right Hemisphere
Reading
Comprehension Area
Frontal Lobe
Occipital Lobe
Sensory Speech
Motor Speech
Parietal Lobe
Cerebellum
Temporal Lobe
Occipital Lobe
Pons
Medulla Oblongata
FIGURE 15.7a
The three layers of meninges that
envelop the central nervous system.
1712 Chapter 08 – Nutrition
FIGURES 15.7b and c
The two hemispheres and four lobes of the human brain.
contrast, the regimes of righteous Jewish kings, such as David and Solomon,
portray monarchy in a totally different way than the way it is usually thought
of today. True Jewish monarchy serves to perfect society by promoting justice
and loving-kindness. The righteous kings of Israel took the Jewish people
(and the world) in directions that they could not go on their own. Likewise,
in the CNS, the brain has the capacity to provide the functional wisdom to
lead the body and fulfill its purpose.
Another parallel between the Torah and the nervous system is related to the
typography of the Torah. There are four typographical levels in the Torah
text: the letters, the crowns inscribed on the top of the letters, the vowels
(without which the letters cannot unite to form audible words), and the
ta’amim, the cantillation marks (in Yiddish, the trop), literally the “tastes” (or
“reasons”) that define the sentence structure and serve as musical notation for
chanting the verses of the text.
The letters and crowns atop the letters in the Torah scroll are revealed to the
eye and correspond to the revealed levels of Torah interpretation, peshat and
remez. (See illustration on the right.) The vowels and the ta’amim are hidden
and correspond to the concealed levels of Torah interpretation, derush and
sod.
Crowns adorning letters
The etnachta
mark
The sof pasuk
mark
Above is the first verse in the Book of Exodus
(chapter 1, verse 1), describing the descent
of Jacob and his household to Egypt. In this
presentation, the words are written with the
crowns on top of
the letters (only
some letters have
crowns), with the
vowel signs (in red), the cantillation marks that
are kings (in blue), and cantillation marks that are
servants (in gray).
©Torah Science Foundation
These four typographical levels correspond to the four levels of consciousness
represented by the four letters of God’s essential Name, Havayah. The first
letter of the Name, the yud, represents the highest level of consciousness,
which is Divine consciousness. This is the level of the ta’amim in the Torah
text, the music of the Torah. The ta’amim are cantillation marks that indicate
both the melody to be used for each word, and the overall cadence of the
verse. So the ta’amim are both a musical shorthand and a guideline to the
grammatical structure of the text.
The individual ta’amim (which are not individual notes but complete
bars of notes) are divided into two categories, the kings and the servants,
similar to the way we picture the Central Nervous System in relation to the
Peripheral Nervous System. The major divisions of the sentence structure
of the verses of the Torah are determined by the kings, but the servants add
(bring) information (musical eloquence) to the king so that his statements
(intonations) carry full weight.
In a Torah scroll, the text would appear with only
the letters and their crowns, as depicted in the
image above, right.
Among the cantillation marks considered kings,
there is an inner hierarchy, with two of them, the
etnachta and the sof pasuk (see illustration on
top), designated as emperors—the highest level.
Since Hebrew is written from right to left, all the
cantillation marks found to the right of a king (all
the way to the previous king) are considered part
of its entourage.
The comparison of the nervous system to the highest level of the Torah, the
ta’amim, is most significant. In the Torah we find the idiom ta’am veda’at
(taste/reason and knowledge). From this we learn that the ta’amim relate in
particular to the sefirah of knowledge (da’at), the seat of the nervous system
among the physiological systems of the human body.
Thus, we could say that singing the song of the Torah (the Torah in its
entirety is God’s song to man) brings about healing to the nerves. (Sing the
Torah and you’ll never need to see a neurologist or a psychiatrist!)
Kabbalah explains that before receiving a new, higher level of consciousness
(a revelation of a higher level of one’s soul), one must enter a state called
“second (spiritual) pregnancy.” One must return to the womb and be born
anew (as is the Mashiach every instant). All of this is a function of the brain
in its womb, the skull.
Torah of Life – An Integrated Torah-biology Textbook 1713
Anatomy of the Brain
FIGURE 15.8
The cerebrum and the cerebellum
The brain in an average adult weighs around three pounds (1.3-1.4 kg).
Although it is only around 2% of the body’s weight, it uses 20% of the
oxygen supply and 20% of the blood supply. The brain is divided into three
distinct sections: the cerebrum, the cerebellum, and the brain stem, made up
of the pons and the medulla oblongata (Figure 15.8).
Cerebrum
Cerebral Cortex:
Outer Layer of
the Cerebrum
Cerebellum
Corpus Callosum
Pons
(Brain Stem)
Medulla Oblongata
(Brain Stem)
The cerebrum is the largest and uppermost part of the brain. It controls
voluntary actions, speech, senses, intelligence, thought, and memory. A deep
groove in the cerebrum, known as the longitudinal fissure, runs from the
back of the head to the front, and divides it into two hemispheres, the right
and left hemispheres (Figure 15.7b).
Each hemisphere controls the opposite side of the body. Thus, the left side
receives sensory information from and controls the movements of the right
side of the body, while the right side of the brain receives information from
and controls the movements of the left side of the body.
©Torah Science Foundation
The two hemispheres are connected at their base by a band of tissue called
the corpus callosum that has 200-250 million neurons, and allows each side
of the brain to communicate with the other (Figure 15.8).
Cerebellum
Corpus Callosum
Brain Stem
In addition, it appears that the right hemisphere is linked to creative and
artistic aptitude, whereas the left hemisphere is linked to mathematical and
analytical aptitude.
Each hemisphere is subdivided into lobes, which are named for the section
of the skull covering them (Figure 15.7c). The frontal lobes are associated
with intelligence, personality, speech, and motor development. The temporal
lobes are responsible for memory, language, hearing, and speech functions.
The parietal lobes are involved with sensation or touch. The occipital lobes
are the primary centers of vision.
Much of what we know about the function of individual sections of the
brain comes from correlating brain injuries with various dysfunctions
in those who have suffered brain damage or illness. However, the
correspondence may be imprecise.
In addition to the right and left divisions of the cerebrum, there is also an
outer and inner division of each of the hemispheres. The outer layer is called
the cerebral cortex (Figure 15.8) and is gray in color due to the unmyelinated
axons that make up this area.
The inner layer is whitish in color, due to the presence of myelin sheaths
covering the axons in this region.
The cerebral cortex is only 2-4 mm (0.08-0.16 in) thick, but convolutions
and crevices (called gyri and sulci, respectively) on the surface of each
hemisphere greatly increase the available area for information processing and
storage.
The right and left hemispheres of the cerebrum correspond to wisdom
(chochmah) and understanding (binah), the father and mother principles,
respectively. The inner experience that accompanies the flash of wisdom
1714 Chapter 08 – Nutrition
generated by a new insight is a sense of selflessness. The inner experience
that accompanies the understanding of an idea in full is joy, the joy of
conception.
We have a sense of success when we integrate the flash of wisdom with a
sense of imminent motherhood as we give birth to a full-fledged emotion
in the heart. The sense of selflessness emanates from the right hemisphere of
the cerebrum, and the sense of joy from the left. These two feelings should
always be present and balanced in our consciousness. The band of tissue that
connects the two sides of the cerebrum is the interface between wisdom and
understanding.
Primarily “right hemisphere” people are more intuitive and fast to act on
what first comes to mind. Primarily “left hemisphere” people are more
rational and deliberate, and they tend to act on second thought. The
functions of the four lobes of the cerebrum can be summed up as: Frontal
lobe – intelligence, Occipital lobe – seeing, Temporal lobe – hearing, and
Parietal lobe – touch.
©Torah Science Foundation
The frontal lobe is relatively active (it analyzes, makes decisions, and controls
speech), while the other three are receptive (they are sensors and interpreters
of sensations). The frontal lobe includes all three faculties of the intellect –
wisdom, understanding, and knowledge, which relate to seeing, hearing, and
touch, respectively.
Gray (which includes all shades of gray) is the color associated with the
attribute of knowledge (da’at), the sefirah which corresponds in particular to
the nervous system. White is the color of the crown (keter), the unconscious
origin of knowledge, the root of the nervous system. So we have white,
crown, and grey, knowledge. The myelin sheaths that give the white matter
its color are produced by the essential fatty acids as mentioned above,
corresponding in the soul to the emotive attribute of compassion (tiferet).
The more grooves found in the tissue, the more room to hold information
and gain new insight and comprehension. In Hebrew, one of the synonyms
of “to think” or “to contemplate” is the same as “to plow.” A deep thinker
plows new grooves in his brain, thus expanding his cognitive power. He
“seeds” every “furrow” of his mind with insight and “reaps” comprehension.
The cerebral cortex is responsible for information processing in general,
including thinking, perceiving, producing and understanding language,
memory, social skills, problem-solving, and advanced motor functions.
The cerebellum (Latin for “little brain”) is considerably smaller than the
cerebrum, and is located below the cerebrum at the back of the head at
the base of the skull, above the brain stem (Figure 15.8). It is involved in
the coordination of voluntary motor movement, balance, and equilibrium.
In striking contrast to the cerebrum, the outer surface of the cerebellum
is covered with narrowly spaced parallel grooves, like a tightly folded
accordion.
The brain stem, a structure continuous with the spinal cord, connects the
brain and the spinal cord to each another. It is located below the cerebellum
and consists of the midbrain, the medulla oblongata, and the pons.
Torah of Life – An Integrated Torah-biology Textbook 1715
The brain stem (Figure 15.8) controls responses to sight, eye movements,
pupil dilation, body movement, and hearing. It is also involved in control of
the autonomic functions of the body, such as heart rate, blood pressure, and
breathing. The brain stem also relays nerve signals between the brain and the
spinal cord, and coordinates body movements.
FIGURE 15.9
The Thalamus and the Hypothalamus
Thalamus
Frontal Lobe
Hypothalamus
The brain stem connects the brain to the spinal cord, thereby connecting
the brain to the body. On the spiritual plane, this is exactly the place in the
Jewish psyche that Amalek, the archenemy of Israel, opposes, trying to injure
the brain stem and make it dysfunctional, or disconnected from the rest
of the body. This is also hinted to in his name, which can be divided into
two— Am and Malek— the nation (am) which decapitates (called melika
in Hebrew). He is out to prevent the mind from ruling the heart and the
body, not only on the conscious plane but primarily on the subconscious,
involuntary plane.
As the Ba’al Shem Tov taught, both Amalek and “doubt” have the same
numerical value of 240. He is actually considered to be a reincarnation of
the primordial snake who seduced Eve to eat from the forbidden fruit. He
poisons the mind with skepticism, which results in psychological impotency
and inability to properly control the body functions. He is thus responsible
for such conditions as high blood pressure, asthma, etc. We are commanded
to annihilate him, may it be soon!
©Torah Science Foundation
The Thalamus and the Hypothalamus
The thalamus (from a Greek word meaning “room” or “chamber”) (Figure
15.9) receives signals from the sensory receptors throughout the body. Some
of its functions are to relay sensations, spatial sense, and motor signals to the
cerebral cortex for further processing. Like the cerebrum, it has two lobes,
right and left, each of which is situated near the center of the brain, beneath
each cerebral hemisphere, on top of the brain stem between the cerebral
cortex and the midbrain.
The hypothalamus (Figure 15.9) produces hormones that control body
temperature, hunger, thirst, mood, and sleep. These hormones also act on
numerous glands, such as the pituitary gland, to coordinate the nervous
and endocrine systems. The pituitary is only about the size of a pearl and is
located below the thalamus, just above the brain stem (Figure 15.8).
The Spinal Cord
The spinal cord extends through the hollow vertebrae of the spinal column
for most of its length (Figure 15.2). It consists of millions of nerve fibers,
which transmit sensory signals from the body to the brain, and motor signals
from the brain to the body. It is about the diameter of a human finger.
Thirty-one pairs of spinal nerves branch out from the spinal cord connecting
the brain and all parts of the body. The nerves that exit the spinal cord in the
upper section (the neck) control breathing and the movement of the arms.
The nerves that exit the spinal cord in the mid and lower section of the back
control the trunk and legs, as well as the bladder, bowel, and reproductive
organs.
1716 Chapter 08 – Nutrition
Certain reflexes are processed locally in the spinal cord, before reaching
the brain. This automatic, fast response of a reflex to a particular stimulus
is crucial in avoiding dangerous situations. For example, the automatic
response to the touching of an extremely hot surface is to pull your hand
away. This response relies on a reflex pathway in the spinal cord, and does
not require stopping to think about how to respond (see below).
The Peripheral Nervous System
The Peripheral Nervous System (PNS) includes the whole nervous system,
except for the brain and spinal cord. The nerves in the peripheral nervous
system connect the CNS to sensory organs (such as the ears and nose),
muscles, blood vessels, glands, and other organs of the body. The peripheral
nerves include the 12 cranial nerves that pass through small openings in
the skull, the spinal nerves and roots, the ganglia (collections of nerve cell
bodies), and the autonomic nerves (Figures 15.2 and 15.10). The PNS is
made up of sensory neurons and motor neurons, depending on the direction
that the impulses travel.
©Torah Science Foundation
Sensory neurons relay nerve impulses from the sense organs toward the
CNS, while motor neurons relay nerve impulses from the CNS to the
muscles and glands. Motor neurons are further subdivided by function into
the somatic nervous system and the autonomic nervous system.
The somatic nervous system is associated with activities that are under
a person’s conscious control, such as the movement of parts of the body
via the skeletal muscles. For this reason, it is also called the voluntary
nervous system because its responses can be controlled voluntarily. Reflex
reactions— involuntary reactions to external stimuli, such as blinking,
sneezing, or yanking your hand away from a hot stove— are an exception to
the overall voluntary character of the somatic nervous system.
FIGURE 15.10
The Sympathetic and Parasympathetic
Divisions of the Autonomic Nervous
System. The two systems innervate the
same organs but have opposite effects.
Sympathetic Division
Brain
Parasympathetic Division
Dilates Pupil
Constricts Pupil
Accelerates
Heart Rate
Inhibits
Heart Rate
Dilates
Bronchi
Constricts
Bronchi
Stimulates
Stomach Mobility
Inhibits
Stomach Mobility
Inhibits
Intestinal
Mobility
Stimulates
Intestinal
Mobility
Spinal Cord
Torah of Life – An Integrated Torah-biology Textbook 1717
As explained above, the sensory division of the peripheral nervous system
is “chash” (silence) and the motor division is “mal” (speech). The 12
cranial nerves control the sense of smell, vision and eye movement,
chewing, and swallowing, the muscles of the tongue, movement, the entire
parasympathetic nervous system, hearing and balance, and taste. We can
now understand why Kabbalah talks about 12 “senses” rather than only the
5 traditional senses of sight, hearing, taste, touch, and smell. Included in the
12 “senses” are the “senses” of speech, concentration (or focus or thought),
walking, action, sleep, anger, eating, and laughter.
The Ba’al Shem Tov was in keen control of his somatic nervous system.
He would never move a finger without a clear purpose. The slightest
physical movement of his body had a spiritual intention (or “unification,” a
meditation, that needn’t take more than a split second, to unify the Creator
and His creation, to unify the infinite and the finite). He was not selfconscious but Divine-conscious, for he was conscious of the fact that we
are no more than an “actual part of God above.” And so it is said of Rabbi
Elimelech of Lizhensk, a disciple of the disciple of the Ba’al Shem Tov, that
angels would run to observe him raising or lowering his small finger!
©Torah Science Foundation
Muscles move involuntarily via nerves that connect directly to the spinal
cord. This is known as a reflex arc (Figure 15.11), which loops from sensory
receptors (e.g., in the hand touching a hot stove) via sensory neurons
connected to the spinal cord, and back via motor neurons to muscles in the
arm. In this way, reflexes occur quickly through the local activation of spinal
motor neurons, without having to route signals through the brain. However,
the brain still receives sensory information during the reflex action.
The autonomic nervous system, also known as the involuntary nervous
system, comprises the automatic functions of the body that are not under
conscious control, such as the regulation of glands, the heart and other
internal organs, and the muscles lining the walls of blood vessels.
Interneuron
Neuron
to Brain
Sensory
Neuron
Receptor
Spinal Cord
Muscle
Motor
Neuron
Flame
FIGURE 15.11
A Reflex Arc
A stimulus (flame) causes sensory receptors
in the skin to generate nerve impulses that
travel in sensory neurons to the spinal cord.
Interneurons integrate stimuli from sensory
neurons and relay signals to motor neurons.
The motor neurons convey nerve impulses to
the finger muscle, which cause the finger to
move away from the flame.
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The autonomic nervous system can further be divided into the sympathetic
and parasympathetic systems (Figure 15.10). The majority of organs
controlled by the autonomic nervous system are connected to both
sympathetic and parasympathetic neurons, where each system has the
opposite effect on the organ.
The sympathetic system is responsible for speeding up the heart rate, dilating
pupils, raising blood pressure, and inhibiting digestion. The sympathetic
system is also involved in the so-called “flight or fight” response. This is a
response to potential danger that results in accelerated heart rate and an
increase in metabolic rate. The parasympathetic system acts in the opposite
way by slowing heart rate, contracting pupils, and enhancing digestion. This
is sometimes called the “rest and digest” response.
The two legs, right and left, represent the two powers to accelerate or to
decelerate, to speed up or to slow down. Heartbeat is increased by the
sympathetic nervous system (the sefirah of victory, symbolically the right
leg) and decreased by the parasympathetic nervous system (the sefirah of
acknowledgment, the left leg). Relative to one another, these two systems are
male and female, as it says in the Zohar: “He (male energy, speeding up) is in
victory and she (female energy, slowing down) is in acknowledgment.”
The Ba’al Shem Tov coined an idiom to describe this ideal “marriage” in
the soul: “deliberate agility,” fast (really fast) but slowly (deliberately). These
two systems which function together (as a happily married couple) are
normally unconscious, but some great sages, like the Ba’al Shem Tov and the
Lubavitcher Rebbe, were fully conscious of their autonomic activities and in
conscious control of their heartbeat and other body functions. They are the
two “legs” within the sefirah of knowledge, which in general corresponds to
the nervous system in the human body.
The autonomic nervous system also includes the enteric system that directly
controls the gastrointestinal system in vertebrates. It consists of networks
of neurons in the digestive tract, pancreas, and gallbladder. These neurons
control the secretions emitted by these glands as well as activity in the
muscles that produce peristalsis, the organized muscle contractions that
occur throughout the digestive tract.
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Torah of Life – An Integrated Torah-biology Textbook
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and in our generation, our goal is the unification
of Torah and science.”
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