Download Prentice Hall Biology - Valhalla High School

The Digestive System
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Section:
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Section 38-1
Good Food Sense
Nutrients are molecules that provide the body with energy and materials
for growth. Three kinds of nutrients you eat are called fats, proteins, and
carbohydrates—terms you may have already heard. Think about what they
may mean.
1. Write a brief description of what you think fats, proteins, and
carbohydrates are.
2. Which of these three nutrients do you think should make up the
largest part of your diet? Which should make up the smallest part?
Arrange the three nutrients in order starting from the one that you
should eat the most to the one that you should eat the least.
3. Why might it be unwise to eat too much of the nutrient you listed last?
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Food and Energy
•Cells convert the chemical energy stored in food into ATP
– When food is burned it releases heat energy, which is measured in
calories
•Food also supplies the raw materials used to build and repair body tissues
– These raw materials are used to manufacture new biomolecules
• Food also contains at least 45 substances that your body
cannot manufacture
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Carbohydrates
•Main source of energy for the body
– Can be simple
• Mono and disaccharides – found in honey, fruits, sugar cane
– Can be complex
• Polysaccharides – starches found in grains, potatoes, veggies
•Broken down by the digestive system to be absorbed into the blood and
carried throughout the body
– If not used immediately, sugars are converted to glycogen, a
complex carb and stored in the liver and muscles, for future use.
•Not all carbs can be broken down
– Fiber (cellulose) is used to keep your digestive system functioning
properly by helping wastes to move through
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Fats
•Fats (lipids)
– Needed to form cell membranes
•Extra food is stored as fat to protect body organs and insulate the body
•Classified as saturated or unsaturated
– Saturated fats
• Solid at room temperature
• Main cause of high blood pressure, heart disease, obesity and
diabetes
– Unsaturated fats
• Liquid at room temperature
• A healthier choice of fat
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Proteins
•Supply raw materials for growth and repair of skin and muscles
•Have endocrine and circulatory functions
– Ex. insulin, hemoglobin
•Polymers of amino acids
– The body can only synthesize 12 of the 20 amino acids
– The other 8 must be ingested
• Found in meat, fish, milk, eggs
• If they are not ingested, you may become malnourished
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Section:
Figure 38–6 Types of Vitamins
Section 38-1
Vitamin
Sources
Function
A (retinol)
Yellow, orange, and dark green
vegetables; dairy products
Important for growth of skin
cells; important for night vision
D (calciferol)
Fish oils, eggs; made by skin
when exposed to sunlight;
added to dairy products
Promotes bone growth;
increases calcium and
phosphorus absorption
E (tocopherol)
Green leafy vegetables, seeds,
vegetable oils
Antioxidant; prevents cellular
damage
K
Green leafy vegetables; made
by bacteria that live in human
intestine
Needed for normal blood
clotting
B1 (thiamine)
Whole grains, pork, legumes,
milk
Normal metabolism of
carbohydrates
B2 (riboflavin)
Dairy products, meats,
vegetables, whole-grain cereal
Normal growth; part of electron
transport chain; energy
metabolism
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Section:
Figure 38–6 Types of Vitamins
Section 38-1
Vitamin
Sources
Function
C (ascorbic acid)
Citrus fruits, tomatoes, red or
green peppers, broccoli,
cabbage, strawberries
Maintenance of cartilage and
bone; antioxidant; improves iron
absorption; important for healthy
gums, tissue repair, and wound
healing
Biotin
Legumes, vegetables, meat
Coenzyme in synthesis of fat;
glycogen formation; amino acid
metabolism
Choline
Egg yolk, liver, grains, legumes
Required for phospholipids and
neurotransmitters
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Section:
Figure 38–7 Types of Minerals
Section 38-1
Mineral
Calcium
Phosphorus
Potassium
Sources
Diary products; salmon; sardines;
kale; tofu; collard greens; legumes
Dairy products; meats; poultry; grains
Meats; dairy products; many
fruits and vegetables; grains
Function
Bone and tooth formation; blood clotting;
nerve and muscle function
Bone and tooth formation; acid-base balance
Acid-base balance; body water balance;
nerve function
Chlorine
Table salt; processed foods
Acid-base balance; formation of gastric juice
Sodium
Table salt; processed foods
Acid-base balance; body water balance;
nerve function
Magnesium
Whole grains; green leafy vegetables
Activation of enzymes in protein synthesis
Iron
Meats; eggs; legumes; whole grains;
green leafy vegetables; dried fruit
Component of hemoglobin and of electron
carriers used in energy metabolism
Fluorine
Fluoridated drinking water; tea;
seafood
Maintenance of tooth structure; maintenance
of bone structure
Iodine
Seafood; dairy products; iodized salt
Component of thyroid hormones
Zinc
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Section:
Meats; seafood; grains
Component of certain digestive enzymes
Figure 38–8 Food Guide Pyramid
Section 38-1
Fats, Oils, and Sweets (use sparingly)
Soft drinks, candy, ice cream, mayonnaise, and
other foods in this group have relatively few
valuable nutrients.
Milk, Yogurt, and Cheese Group
(2-3 Servings)
Milk and other dairy products are rich in
proteins, carbohydrates, vitamins, and
minerals.
Vegetable Group
(3-5 servings)
Vegetables are a low-fat
source of carbohydrates,
fiber, vitamins, and minerals.
Fats
Sugars
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Meat, Poultry, Fish, Dry Beans, Eggs,
and Nut Group
(2-3 servings)
These foods are high in protein.
They also supply vitamins and minerals.
Fruit Group
(2-4 servings)
Fruits are good sources of
carbohydrates, fiber, vitamins
and water.
Bread, Cereal, Rice
and Pasta Group
(6-11 servings)
The foods at the base of the
pyramid are rich in complex
carbohydrates and also
provide proteins, fiber,
vitamins, and some
minerals.
Concept Map
Section 38-1
Nutrients
include
Carbohydrates
Fats
Proteins
Vitamins
Minerals
include
are made of
are made using
include
include
Simple
Complex
such as
such as
Amino
acids
Fatty Acids
Sugars
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Starches
Calcium
Glycerol
Fat-soluble
Watersoluble
Iron
Section Outline
Section 38-2
38–2
The Process of Digestion
A. The Mouth
1. Teeth
2. Saliva
B. The Esophagus
C. The Stomach
1. Chemical Digestion
2. Mechanical Digestion
D. The Small Intestine
Accessory Structures of Digestion
E. Absorption in the Small Intestine
F. The Large Intestine
G. Digestive System Disorders
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Section:
Figure 38–10 The Digestive System
Section 38-2
Mouth
Pharynx
Salivary glands
Esophagus
Liver
Gallbladder
(behind liver)
Stomach
Pancreas (behind
stomach)
Large intestine
Small intestine
Rectum
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Section:
The Mouth
•Performs mechanical and chemical digestion
– Mechanical – food is changed in size
• Performed by the teeth
– Chemical – food is changed in composition
• Performed by saliva
– Contains amylase (an enzyme that breaks down starch)
– Also helps to moisten food so it can move easier
– Contains lysozyme (an enzyme used to kill bacteria)
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The Esophagus
•Lined with smooth (involuntary) muscle
•As the food passes through, contractions, known as peristalsis, squeeze
the food through to the stomach
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Stomach
•A large muscular sac
– Continues mechanical and chemical digestion
• Mechanical – churning of food and stomach acids to form
chyme
• Chemical – stomach glands release a variety of secretions
– Chemical digestion continues in the small intestine
– Chyme then leaves the stomach and enters the small intestine
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Small Intestine (SI)
•Duodenum (1st part of the SI) where almost all of the digestive enzymes
enter from accessory organs
– Shortest part of the SI
•Jejunum and Ileum (2nd & 3rd parts)
– Where absorption of nutrients occurs
– Villi – increase surface area to allow for greater absorption
• Contain capillaries and lymph vessels
•Water, cellulose and other undigestible substances leave the SI and enter
the large intestine
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Figure 38–14 The Small Intestine
Section 38-2
Villus
Small Intestine
Circular folds
Epithelial cells
Villi
Capillaries
Lacteal
Vein
Artery
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Section:
Accessory Organs
•Pancreas
– Produces enzymes, that break down carbs, proteins, lipids and
nucleic acids
– Also produces sodium bicarbonate to neutralize stomach acids so
the enzymes will work (only work under certain pH)
•Liver
– Produces bile, which dissolves and disperses droplets of fats, so
that the enzymes can work on the smaller fat molecules
•Gall Bladder
– Stores the bile that is produced by the liver
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Figure 38–13 The Liver and the Pancreas
Section 38-2
Liver
Bile duct
Gallbladder
Pancreas
Pancreatic duct
Duodenum
To rest of small intestine
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The Large Intestine (LI)
•Also known as the colon
•Primary function is to absorb water from undigested
materials
•Rich colonies of bacteria that are present in the LI
produce compounds that the body is able to use, like
vitamin K.
•The concentrated waste material that remains after the
water has been removed passes through the rectum,
where it is stored until it is eliminated from the body
through the anus.
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Section:
Figure 38–10 The Digestive System
Section 38-2
Mouth
Pharynx
Salivary glands
Esophagus
Liver
Gallbladder
(behind liver)
Stomach
Pancreas (behind
stomach)
Large intestine
Small intestine
Rectum
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Section:
Diseases of the Digestive System
Diarrhea
-frequent loose or liquid bowel movements
-The large intestine is responsible for re-absorption of water. If this does not occur,
too much water may be eliminated from the body along with fecal matter.
-Upsets the body’s electrolyte balance unless fluids are replaced.
Constipation
- stools are usually hard, dry, small in size, and difficult to eliminate
- if the large intestine absorbs too much water, the fecal matter becomes very hard
and is unable to pass through the colon to the rectum.
- treatment can include change in diet, more physical exercise and laxatives
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Section:
The Excretory System
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Section Outline
Section 38-3
38–3
The Excretory System
A. Functions of the Excretory System
B. The Kidneys
1. Kidney Structure
2. Filtration
3. Reabsorption
4. Kidney Stones
C. Control of Kidney Function
D. Homeostasis by Machine
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Section:
Functions of the Excretory System
•Every cell in the body produces wastes as a result of maintaining
homeostasis
– Wastes such as urea, excess salts and carbon dioxide must be
removed from the body
•The skin, lungs and liver are three organs that assist in excretion
– The skin excretes excess salts, water and a small amount of urea
– The lungs excrete carbon dioxide
– The liver takes excess amino acids from the blood stream and
converts them to useful compounds
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Kidneys
•The kidneys have many roles
– Remove waste products from the blood
– Maintain blood pH
– Regulate the water content of the blood and therefore blood volume
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Kidney Structure
• Contains nephrons – the functional units of the kidney
– Each one is a small, independent unit
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Nephron
•Each nephron has its own blood supply
– An arteriole, a venule and a network of capillaries
•Each nephron releases fluid into a collecting duct, which leads to the
ureters
•The ureters carry urine (water, salts and urea) to the bladder
– Urine is then stored in the bladder until it is released from the body
through the urethra
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Section:
The Urinary System
Section 38-3
Vein
Kidney (Cross Section)
Kidney
Cortex
Medulla
Ureter
Urinary bladder
Urethra
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Artery
Disease
•Kidney Stones
– Substances such as calcium, magnesium or salts in the urine
crystallize and form stones
– These stones may block the ureter, causing great pain
– Often treated using ultrasound waves
• The stones gets pulverized into smaller fragments, which are
then excreted in the urine.
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Homeostasis by Machine
•Dialysis
– Blood is removed from the body through a tube and pumped
through special tubing that acts like nephrons
– Wastes diffuse out of the blood and into a fluid-filled chamber
– The purified blood is then returned to the body
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Figure 38–19 Kidney Dialysis
Section 38-3
Blood in tubing flows
through dialysis fluid
Blood pump
Vein
Artery
Used dialysis fluid
Shunt
Air detector
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Dialysis
machine
Fresh
dialysis
fluid
Compressed
air