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Martini’s Visual
Anatomy and Physiology
First Edition
Martini w Ober
Chapter 22
Nutrition and Metabolism
Lecture 10
1
Lecture Overview
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Nutrition, nutrients, and metabolism
Macronutrients
Energy and energy requirements
Vitamins
Minerals
Nutritional abnormalities
Life-span changes
2
Nutrients
Nutrients – chemical substances supplied by the
environment required for survival (used for
growth, repair, or maintenance of the body)
Macronutrients
• carbohydrates
• proteins
• fats
Micronutrients
• vitamins
• minerals
Essential Nutrients
• human cells
cannot
synthesize
• include
certain fatty
acids, amino
acids, vitamins
3
Review of General Metabolic Pathways
(6C)
(3C)
Overall goal of
catabolism is to
generate a pool
of 2- or 3-carbon
molecules – the
intermediates of
metabolism – as
well as energy
(ATP)
(2C)
4
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Carbohydrates
Sources
• sugars (simple)
• starches (complex) - usually
from plant sources
• glycogen (complex) in meats
• cellulose (complex) is
indigestible fiber
Excesses lead to
• obesity
• dental caries
• nutritional deficits
Deficiencies lead to
• metabolic acidosis
• weight loss
Recommended (Dietary) Daily Allowance (RDA) is
125-175g
*
5
Utilization of Carbohydrates
Glucose is the body’s CHO energy source
Figure from: Hole’s Human A&P, 12th edition, 2010
7
Lipids
Sources
• meats
• eggs
• milk
• lard
• plant oils
Excesses lead to
• obesity
• increased serum
cholesterol
• increased risk of
heart disease
RDA is 80-100g
( 30% of calories)
( 10% saturated fat)
Deficiencies lead to
• weight loss
• skin lesions
• hormonal imbalances
Fats generally take the longest to digest. Why?
8
Utilization of Lipids
Figure from: Saladin,
Anatomy & Physiology,
McGraw Hill, 2007
How is fat
absorbed from
the digestive
tract?
Know these
terms (see table
of these terms
later in this
lecture)
Oxaloacetic
acid
*
9
Energy Values of Food
Calorie (kilocalorie, big calorie) – amount of heat needed
to raise the temperature of 1 kg of water by 10 C
Carbohydrates
4.1 Calories per gram
Proteins
4.1 Calories per gram
Lipids
9.5 Calories per gram
Diet is 2000 Calories. What is the
maximum number of grams of fat
that should be taken in daily?
How many grams of fat are there
in a Whopper with cheese and a
small order of french fries?
Know this - you can round these off to the 4, 4, and 9)
11
Lipoprotein Traffic
Figure From:
Martini, Anatomy
& Physiology,
Prentice Hall, 2001
TG-rich
Cholesterol-rich
*Cholesterol can
be manufactured
from Acetyl-CoA
Note the role of HDLs
as scavengers of
tissue/blood
cholesterol.
12
Summary of Lipoproteins
Designation
Origin
Action
Chylomicron
GI tract
Transports dietary fats
(mainly triglycerides) to liver
for processing
Very Low Density
Lipoprotein (VLDL)
Liver
Transports triglycerides from
liver to adipose cells
Low Density
Lipoprotein (LDL)
Liver
Transports cholesterol from
liver to cells in body
High Density
Lipoprotein (HDL)
Liver
Removes excess cholesterol
from cells and transports to
liver
13
Know this chart
Utilization of Lipids
The liver uses fatty acids to synthesize a variety of lipids
Figure from: Hole’s Human A&P, 12th edition, 2010
Triglyceride
Linoleic, linolenic (plant oils)
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Proteins
Sources
• meats
• cheeses
• nuts
• legumes
Incomplete proteins – unable to
maintain human tissues or
support normal growth and
development by themselves
Excesses can lead to obesity
Deficiencies lead to
• extreme weight loss
• muscle wasting
• anemia
• growth retardation
*RDA is 0.8g/kg body
weight or 10% of diet
(1 kg = 2.2 lbs)
Essential amino acids (10; 8 in adult)– cannot be synthesized
by the body (isoleucine, leucine, lysine, threonine, tryptophan,
phenylalanine, valine, and methionine; arginine, histidine)
15
Utilization of Proteins
Figure from: Hole’s Human A&P, 12th edition, 2010
• build cell structures
• enzymes
• hormones
• transport of oxygen
• regulation of water balance
• control of pH
• formation of antibodies
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Utilization of Proteins for Energy
Ammonia, NH3, or
ammonium, NH4+
Highly toxic, even
in small amounts
Liver converts these
to urea, a harmless
water-soluble
compound that can
be excreted in the
urine
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Figure from: Hole’s Human A&P, 12th edition, 2010
*
Nitrogen Balance
Variety of compounds in the body contain nitrogen (N):
amino acids, purines, pyrimidines, creatine, porphyrins.
The body neither stores nor maintains reserves of N.
There’s only about 1 kg of N in body at any one time.
During starvation, N-containing compounds, like skeletal
muscle, are conserved; CHO and fats are metabolized first
(protein-sparing effect). Order of usage: CHO, fat, protein.
• nitrogen balance - amount of nitrogen taken in is equal to
amount excreted
• negative nitrogen balance develops from starvation
• positive nitrogen balance develops in growing children,
pregnant women, or an athlete in training
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The “Fed” (Absorptive) State
Know this
20
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
The “Fasted” (Postabsorptive) State
Know this
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Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Metabolism
-olysis  breakdown of
-genesis  creation of
-neo  new
Hormones:
Fed – Insulin
Fasted – Glucagon, Corticosteroids,
Epi/NE
• Glycolysis – metabolism of glucose to pyruvate (Fed)
• Gluconeogenesis – metabolism of pyruvate to glucose (CHO
from non-CHO source) – (Fasted)
• Glycogenesis – metabolism of glucose to glycogen (Fed)
• Glycogenolysis – metabolism of glycogen to glucose
(Fasted)
• Lipolysis – breakdown of triglyceride into glycerol and fatty
acids (Fasted)
• Lipogenesis – creation of new triglyceride (fat) – (Fed)
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Energy Requirements
Basal metabolic rate (BMR)
• rate at which body expends energy at rest
(kcal/hr)
• primarily reflects energy needed to support
activities of organs
BMR is proportional
• varies with gender, body size, body
to body weight
temperature, and endocrine function
Energy needed
Body’s basal
• to maintain BMR
metabolic rate
• to support resting muscular activity
(BMR) falls 10%
• to maintain body temperature
during sleep and
• for growth in children and pregnant
about 40% during
women
prolonged starvation
BMR is profoundly affected by circulating
23
thyroid hormone levels
Energy Balance
• occurs when caloric intake in the form of food
equals caloric output from BMR and muscular
activities
• positive energy balance leads to weight gain
• negative energy balance leads to weight loss
Body Mass Index (BMI)* = Wt (kg) / Height2 (m)
Thin
< 18.5
Healthy or Normal
18.5 – 24.9
Overweight
25.0 – 29.9
Obese
30.0 – 39.9
Morbidly Obese
 40.0
* Source: World Health Organization
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Overview of Vitamins
• Organic substances required in small
amounts that are not synthesized in
adequate amounts to meet the body’s needs
• Divided into two groups by solubility
– Water-soluble – vitamins B (group) and C
• Not generally stored
• Excesses are excreted, e.g., in urine
– Fat-soluble – vitamins A, D, E, and K
• Stored in liver, adipose, other tissues
• Excesses accumulate in tissues
25
The Fat-soluble Vitamins
• Absorbed with fats in digestive tract
• Function/Other sources
– Vitamin A; structural component of retinal
– Vitamin D
• increases absorption of calcium and phosphorus
from intestine
• skin and UV light
– Vitamin E
• stabilizes internal cellular membranes
• antioxidant
– Vitamin K
• Clotting (‘K’lotting)
• bacteria in intestine and green, leafy vegetables
*
26
Water-soluble Vitamins
• Rapidly exchanged between fluid compartments of
digestive tract and circulating blood
• Excesses excreted in urine
• Vitamins B12 and C are stored in larger quantities
than other water-soluble vitamins
– B vitamins [know these functions]
• as a group, are coenzymes used to harvest energy
• Vitamin B12 is important in hematopoiesis and maintenance of
myelin sheath and epithelial cells
– Vitamin C (ascorbic acid) [know these functions]
• collagen production
• Antioxidant / immune system booster
•  absorption of iron
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History of USDA’s Food Guidance
Slide from: http://www.mypyramid.gov/downloads/MyPyramid%20Peer%20to%20Peer.ppt
Food for
Young
Children
1992
1916
1940s
1970s
2005
1950s-1960s
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USDA Food Pyramid(2005) and Food Plate (2011)
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Food Pyramid
From: http://www.mypyramid.gov/downloads/MyPyramid%20Peer%20to%20Peer.ppt
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Harvard School of Public Health
Source: http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/pyramid/
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Malnutrition
• poor nutrition
• undernutrition – deficiency of essential nutrients
• overnutrition – excess of nutrient intake
• primary malnutrition – malnutrition from diet alone
• secondary malnutrition – diet is sufficient but
nutrients cannot be absorbed, e.g., insufficient bile
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Starvation
• person can survive 50-70 days without food (but
vitamin deficiencies and their effects begin to appear
after a week or two)
• symptoms include metabolic acidosis, low blood
pressure, slow pulse, chills, dry skin, hair loss, and poor
immunity
• Marasmus – lack of all nutrients
• Kwashiorkor – protein starvation
• Anorexia nervosa – eating disorder; self-starvation
• Bulimia – eating disorder; bingeing and purging
Body will adapt to starvation by using CHO first, then
fats, and finally protein
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*
I didn’t want to say anything, Dear, but…
A mutation in the leptin
gene in the ob/ob mouse
(Right) leads to morbid
obesity and provides an
excellent experimental
model.
36
Review
*Mineral
*Symbol
*Major/Trace
Primary
Distribution
*Major
Function(s)
Major
Sources
Conditions
*Calcium
Ca
Major
Bones & Teeth
Structure of
bone/teeth;
nerve impulse
conduction;
muscle contraction
milk;
+ kidney
stones
- stunted
growth
*Phosphorus
P
Major
Bones & Teeth
Structure of
bone/teeth;
ATP;
Nucleic acid &
proteins
meats;
cheese;
milk
+ none
- stunted
growth
*Potassium
K
Major
Intracellular Fluid
maintenance of resting
membrane
potential (RMP)
avocados;
bananas;
potatoes
+ none
- muscular &
cardiac
problem
s
Sulfur
S
Major
skin, hair, nails
essential part of amino
acids, thiamine,
insulin, biotin,
and MPS
meats;
milk;
eggs
+ none
- none
*Sodium
Na
Major
Extracellular Fluid
maintenance of RMP,
electrolyte,
water, & pH
balance
table salt;
cured ham
+ hypertension,
edema
- cramps,
convulsi
ons
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Review
*Mineral
*Symbol
*Major/Trace
Primary
Distribution
*Major
Function(s)
Major
Sources
Conditions
*Chlorine
Cl
Major
Extracellular
Fluid
maintenance of RMP,
electrolyte, water, &
pH balance
table salt;
cured ham
+ vomiting
- muscle
cramps
*Magnesium
Mg
Major
Bones
needed in mitochondria
for cellular respiration;
ATP/ADP conversion
milk;
dairy;
legumes
+ diarrhea
- neuromuscular
problems
*Iron
Fe
Trace
Blood
part of hemoglobin
liver
+ liver
damage
- anemia
Manganese
Mn
Trace
liver, kidneys
occurs in many
enzymes
nuts
+ none
- none
Copper
Cu
Trace
liver, heart, brain
essential in synthesis of
hemoglobin, bone,
melanin, myelin
liver;
oysters
crabmeat
+ rare
- rare
*Iodine
I
Trace
thyroid
essential in the
synthesis of thyroid
hormones
iodized
table salt
+ thyroid
hormone
imbalance
- goiter
39
Review
*Mineral
*Symbol
*Major/Trace
Primary
Distribution
*Major
Function(s)
Major
Sources
Conditions
Cobalt
Co
Trace
widely distributed
component of
cyanocobalamin (B12)
liver;
lean meats
+ heart
disease
- pernicious
anemia
*Zinc
Zn
Trace
liver, kidneys,
brain
wound healing; part of
several enzymes
meats;
cereals
+ slurred
speech
- decreased
immunity
Fluorine
F
Trace
bones & teeth
tooth structure
fluoridated water
+ mottled
teeth
- none
Selenium
Se
Trace
liver & kidney
occurs in enzymes
lean meats
cereals
+ vomiting,
fatigue
- none
Chromium
Cr
Trace
widely distributed
essential for use in
carbohydrates
liver;
lean meats
+ none
- none
40
Review
• Metabolism and fate of macronutrients
– Carbohydrate
• Broken down into monosaccharides
• Metabolism, glycogen, fat, pentose sugars
– Lipids
• Saturated vs. unsaturated fats
• Broken down into glycerol and fatty acids
• Used for energy (or storage of energy)
– Proteins
• Complete vs. incomplete proteins
• Broken down into amino acids
• Structural components or energy
41
Review
• Fat-soluble vitamins
– Excesses are stored in tissues (liver, adipose) and not
excreted; may become toxic
– Includes vitamins A, D, E, and K
– For exam see Table 18.8 on p. 708 and know the
functions of the fat-soluble vitamins
• Water-soluble vitamins
– Excesses are excreted, e.g., urine
– Vitamins B and C
– For exam see Table 18.9 on p. 713
• B vitamins – know name/designation and know that the B
vitamins are coenzymes that function in energy metabolism
• Vitamin C – know its name and functions
42