Download File - Mr. Jaeger`s Class

Table of Contents
Chapter: Nutrients and Digestion
Section 1: Nutrition
Section 2: The Digestive System
Nutrition
1
Why do you eat?—Energy Needs
• Nutrients (NEW tree unts) - substances in
foods
provide energy and materials
for cell development, growth, and repair
• body mass, age, and activity level affect how
much energy you need
• comes from the foods you eat
Nutrition
1
Why do you eat?—Energy Needs
• Calories (Cal) - amount of energy available
in food
• amount of heat necessary to raise the
temperature of 1 kg of water 1°C
Nutrition
1
Classes of Nutrients
• Six kinds of nutrients - proteins,
carbohydrates, fats, vitamins, minerals, and
water
• Organic nutrients
- contain carbon Proteins,
carbohydrates,
vitamins, and fats
Nutrition
1
Classes of Nutrients
• Inorganic nutrients - do not contain carbon water and minerals
• Carbohydrates, fats, and proteins need to be
digested
• Water, vitamins, and minerals don’t require
digestion
absorbed directly into bloodstream
Nutrition
1
Proteins
• Proteins - large molecules
contain carbon, hydrogen, oxygen, nitrogen
and sometimes sulfur.
• used for replacement, repair, and growth of
body cells
• amino acids - smaller units that make up
protein
Nutrition
1
Proteins
• only 20 amino acids in various combinations
make thousands of proteins used in cells
• essential amino acids - eight amino acids that
cannot be made in your body’s cells
Nutrition
1
Proteins
• Complete proteins provide all essential amino
acids
• Incomplete proteins are
missing one or more
essential amino acids
• Vegetarians get all
essential amino acids by
eating a wide variety of
protein-rich vegetables,
fruits, and grains.
Nutrition
1
Carbohydrates
• Carbohydrates (kar boh HI drayts) usually are main sources of energy for your
body
• made of carbon, hydrogen, and oxygen atoms
• Energy holds atoms together
• broken down in presence of oxygen in your
cells
energy is released for use by your body
Nutrition
1
Carbohydrates
• Three types sugar, starch, and
fiber
• simple
carbohydrates Sugars
• cells break down
glucose
Nutrition
1
Carbohydrates
• complex carbohydrates - starch and fiber
• Starch - in potatoes & grains such as pasta.
• Made of many simple sugars
in long chains
Nutrition
1
Carbohydrates
• Fiber - found in the cell walls of plant cells
(cellulose)
• whole-grain breads and cereals, beans, peas,
and other vegetables and fruits are good
sources of fibers
• You cannot digest fiber, but it is needed to
keep your digestive system running smoothly.
Nutrition
1
Carbohydrates
• Nutritious snacks can help your body get
nutrients it needs, especially when you are
growing rapidly and are physically active
• Choose smacks that provide nutrients such
as complex carbohydrates, proteins, and
vitamins, as well as fiber
Nutrition
1
Fats
• Fats (lipids) - necessary to provide energy
and help your body absorb vitamins
• cushions your internal organs
• major part of every cell membrane
• A gram of fat can release more than twice as
much energy as a gram of carbohydrate can.
Nutrition
1
Fats
• fat is broken down into smaller molecules fatty acids and glycerol (GLIH suh rawl)
• fat is a good storage unit for energy –
excess energy is converted to fat
and stored for later use
Nutrition
1
Fats
• Fats classified as unsaturated or saturated based on chemical structure
• Unsaturated fats - usually liquid at room
temperature
• Vegetable oils &
fats found in seeds
Nutrition
1
Fats
• Saturated - found in meats, animal products,
and some plants
usually solid at room temperature
• associated with high levels of blood
cholesterol
• can lead to heart disease and strokes
Nutrition
1
Vitamins
• Vitamins - Organic nutrients needed in
small quantities
for growth, regulating body functions, and
preventing some diseases
• bone cells need vitamin D to use calcium
• blood needs vitamin K in order to clot
• Most foods supply some vitamins,
but no food has them all
Nutrition
1
Vitamins
• classified into two groups
• water-soluble vitamins - dissolve easily in
water
• not stored by your body
so you have to take them daily
Nutrition
1
Vitamins
• fat-soluble - dissolve only in fat
• They are stored by your body.
• some vitamins are
made by your body
• Vitamin D is made when
your skin is exposed to
sunlight.
Nutrition
1
Minerals
• Minerals - lack carbon
and regulate many chemical reactions in your
body
• Your body uses about 14 minerals
• build cells, take part in chemical reactions in
cells, send nerve impulses throughout your
body, and carry oxygen to body cells
Nutrition
1
Minerals
• calcium and phosphorus are used in the
largest amounts for a variety of body
functions.
• trace minerals required only in
small amounts
Nutrition
1
Minerals
• This table
lists several
minerals,
what they
do, and
some food
sources for
them
Nutrition
1
Water
• Next to oxygen, water is the most important
factor for survival
• Different organisms need different amounts of
water to survive
• You could live a few weeks without food but
only a few days without water - your cells
need water to carry out their work
• Most nutrients have to be dissolved in
water
• chemical reactions take place in solutions
Nutrition
1
Water
• human body is about 60 percent water by
weight
• two thirds of your body water is located in
body cells
• found around cells
and in body fluids such as blood
Nutrition
1
Water
• Your body loses water as perspiration
• When you exhale, water leaves your body
as water vapor
• also is lost every day
when your body gets rid
of wastes
• you need to drink about
2 L of liquids to replace
water lost each day
Nutrition
1
Why do you get thirsty?
• When your body needs to replace lost water,
messages are sent to your brain that result in
a feeling of thirst.
• Drinking water satisfies your
thirst and usually restores
the body’s homeostasis (hoh
mee oh STAY sus).
Nutrition
1
Food Groups
• Food group - contain the same type of
nutrient
• five groups—bread and cereal, vegetable,
fruit, milk, and meat
• The recommended daily amount for each
food group will supply your body with the
nutrients it needs for good health.
Nutrition
1
Daily Servings
• Each day you should eat:
• six to eleven servings from the bread and cereal
group
• three to five servings from the vegetable group
• two to four servings from the fruit group
• two to three servings from the milk group
• two to three servings from the meat group
• Only small amounts of fats, oils, and sweets
should be consumed.
Nutrition
1
Daily Servings
• The size of a serving is different for
different foods:
• a slice of bread or one ounce of ready-to-eat
cereal for bread-and-cereal
• one cup of raw leafy vegetables or one-half
cup of cooked or chopped raw vegetables for
vegetables
• one medium apple, banana, or orange for fruit
• one cup of milk or yogurt for milk
• two ounces of cooked lean meat or one egg
for meat
Nutrition
1
Food Labels
• The nutritional facts found on
all packaged foods can help
you plan meals that supply the
daily recommended amounts
of nutrients and meet special
dietary requirements (for
example, a low-fat diet).
Section Check
1
Question 1
A _______ is the amount of heat necessary to
raise the temperature of 1 kg of water 1 degree
Celsius.
Answer
The answer is Calorie. The amount of energy
available in food is measured in Calories.
Section Check
1
Question 2
The foods in this illustration are rich in
_______.
A. carbohydrates
B. fat
C. minerals
D. protein
Section Check
1
Answer
The answer is D. Your body uses proteins for
replacement and repair of body cells.
Section Check
1
Question 3
Organic nutrients needed in small quantities for
growth, regulating body functions, and
preventing some diseases are called _______.
A. carbohydrates
B. fats
C. minerals
D. vitamins
Section Check
1
Answer
The answer is D. Taking extra vitamins or
eating a well- balanced diet helps give your
body all the vitamins it needs.
The Digestive System
2
Functions of the Digestive System
• Four stages of digestion —ingestion,
digestion,
absorption, and
elimination.
• ingestion - food
enters your mouth
The Digestive System
2
Functions of the Digestive System
• Digestion – process that breaks down food
into small molecules
so it can be absorbed and moved into blood.
• From blood, molecules are transported across
cell membrane
to be used by cell
• Unused molecules pass out of your body
as wastes
• Digestion is mechanical and chemical
The Digestive System
2
Functions of the Digestive System
• Mechanical digestion - food is chewed,
mixed, and churned
• Chemical digestion - chemical reactions
break down large molecules of food
into smaller ones
The Digestive System
2
Enzymes
• enzyme - type of protein that speeds up
chemical reaction in body
• By reducing amount of energy necessary
for a chemical reaction to begin
• work without being changed
or used up
The Digestive System
2
Enzymes
Click image to view movie.
The Digestive System
2
Enzymes in Digestion
• help you digest carbohydrates, proteins, and
fats
• Amylase (AM uh lays) - enzyme produced
glands near mouth.
• speeds up breakdown of complex
carbohydrates
The Digestive System
2
Enzymes in Digestion
• Pepsin – In stomach - break down complex
proteins
• other enzymes continue to speed up
breakdown of proteins into amino acids in
your small intestine
The Digestive System
2
Enzymes in Digestion
• Pancreas - organ on back side of stomach
releases several enzymes
into small intestine
• sugars are turned into glucose
and used by cells
• Different enzymes from the pancreas
breakdown fats into fatty acids
The Digestive System
2
Organs of the Digestive System
• two parts
—digestive tract
and accessory organs
• major organs of digestive
tract are:
1) mouth, 2) esophagus (is
SAH fuh guhs),
3) stomach, 4) small
intestine, 5) large intestine,
6) rectum, and 7) anus.
The Digestive System
2
Organs of the Digestive System
• accessory organs –
1) tongue, 2) teeth,
3) salivary glands,
4) liver, 5) gallbladder,
and 6) pancreas
The Digestive System
2
Organs of the Digestive System
• liver, gallbladder, and
pancreas - produce or
store enzymes and
chemicals
The Digestive System
2
The Mouth
• Mechanical and chemical digestion begin
in mouth.
• Mechanical digestion - chew food with teeth
and mix with tongue
• Chemical digestion - begins with saliva
(suh LI vuh) - watery substance
The Digestive System
2
The Mouth
• tongue moves food around
and mixes it with saliva
• Saliva produced
by three sets of
glands
The Digestive System
2
The Mouth
• saliva is mostly water –
also contains mucus
and an enzyme (amylase)
• Food mixed with saliva
becomes a soft mass
moved to back of mouth by tongue
• swallowed and passes into esophagus
The Digestive System
2
The Esophagus
• passes over epiglottis (ep uh GLAH tus)
• automatically covers opening to windpipe
so you don’t choke.
• about 25 cm long muscular tube
• 4 s to 10 s for food to move down esophagus
to stomach
The Digestive System
2
The Esophagus
• No digestion takes place in esophagus
• Mucous glands in wall keep food moist
• peristalsis (per uh STAHL sus) - waves of
smooth muscle contractions
move food through entire digestive tract.
The Digestive System
2
The Stomach
• muscular bag
• sausage shaped
with folds on the
inside when empty
• stomach expands
and folds smooth out
as food enters
The Digestive System
2
The Stomach
• Mechanical - food is mixed by peristalsis
• Chemical - food is mixed with enzymes
(Pepsin) and hydrochloric acid solution
The Digestive System
2
The Stomach
• about 2 L of hydrochloric acid solution
each day
• Acidic solution works with pepsin
to digest protein
• destroys bacteria in food
The Digestive System
2
The Stomach
• Mucus makes food slippery
and protects stomach
from strong digestive solutions
• chime (KIME) - thin, watery liquid
2 hours to 4 hours in your stomach
• chime moves out of stomach into small
intestine
The Digestive System
2
The Small Intestine
• small in diameter,
but 4 m to 7 m in length
• Duodenum (doo AH duh num) –
first part of small intestine
where most digestion takes place
• Bile - greenish fluid from liver
added to break up large fat particles
The Digestive System
2
The Small Intestine
• Chemical digestion - bicarbonate ions and
enzymes
from the pancreas
• neutralize stomach acid
• Insulin - a hormone from your pancreas
allows glucose to pass from bloodstream into
cells
The Digestive System
2
The Small Intestine
• Absorption takes place in small intestine
• villi (VIH li) - fingerlike projections on wall
many ridges and folds
The Digestive System
2
The Small Intestine
• Villi increase the surface area
so nutrients in chime
have more places
to be absorbed
The Digestive System
2
The Small Intestine
• Peristalsis continues to move and mix
• Villi move and are bathed in soupy liquid
• Nutrients move into blood vessels within
villi
The Digestive System
2
The Small Intestine
• Then blood transports nutrients to all cells
• undigested and unabsorbed materials forced
by peristalsis into large intestine
The Digestive System
2
The Large Intestine
• When chime enters large intestine
it is still thin, watery mixture
• main job is to absorb water
from undigested mass
The Digestive System
2
The Large Intestine
• undigested materials become more solid
after excess water is absorbed
• Rectum and anus - musclear last section of
large intestine
• Feces (FEE seez) - semisolid wastes released
The Digestive System
2
Bacteria Are Important
• Bacteria live in many organs of digestive
tract
including mouth and large intestine
• bacteria in large intestine feed on cellulose
• make vitamins you need—
vitamin K and two B vitamins
• also converts bile pigments into new
compounds
Section Check
2
Question 1
This illustration represents _______.
A. absorption
B. digestion
C. elimination
D. ingestion
Section Check
2
Answer
The answer is D. Ingestion occurs as food
enters your mouth.
Section Check
2
Question 2
_______ are a type of protein that speeds up
the rate of a chemical reaction in your body.
Answer
The answer is enzymes. Enzymes reduce the
amount of energy necessary for a chemical
reaction to begin.
Section Check
2
Question 3
Which is a major organ in your digestive tract?
A. esophagus
B. gallbladder
C. pancreas
D. salivary glands
Section Check
2
Answer
The answer is A. The major organs of the
digestive tract are mouth, esophagus, stomach,
small intestine, large intestine, rectum, and
anus. Food passes through all of these organs.