CHAPTER 14
7TH GRADE
Section 1 (pages 400-404)
I Digestion
A. Breaks down food into small molecules that can be absorbed by
the body.
B. Occurs in four ways---ingestion, digestion, absorption, and
elimination.
a. Ingestion—taking in food
b. Digestion—breaking down food
c. Absorption—absorbing food into the blood stream
d. Elimination—removal of waste from the body
C. Two types
a. Mechanical digestion—food is chewed, mixed, and churned.
b. Chemical digestion—chemical reactions break down food.
II Enzymes
A. A type of protein that speeds up the rate of a chemical reaction in
your body.
B. Works by
a. Reducing the amount of energy necessary for a chemical
reaction to begin.
b. Help you digest carbohydrates, proteins and fats.
C. Found in the stomach, mouth, small intestine, and pancreas.
III Organs of the digestive tract
A. Mouth—Here, your tongue, teeth, and saliva change food into soft
mass.
B. Esophagus—muscular tube that moves food to the stomach using
peristalsis.
a. Peristalsis—waves of muscle contractions.
C. Stomach—Here, food is digested mechanically by peristalsis and
chemically by digestive solutions with the help of enzymes and
hydrochloric acid. Food becomes a thin, watery liquid called
chyme.
D. Small intestine—Villi increase the surface area to increase
absorption. Blood transports the absorbed nutrients to cells.
E. Large intestine—Absorbs water from undigested chyme. The
rectum and anus control the release of solid wastes from the body.
IV Bacteria in the digestive tract
A. Can be found in the mouth and large intestine.
B. They can change undigested material like cellulose into Vitamin K
and two types of B vitamins.
C. Vitamin K—in needed for blood clotting.
D. B vitamins—niacin and thiamine are important for your nervous
system and for other body functions.
Section 2 (page 405-410)
Nutrition
A. Your body needs nutrients found in foods.
a. Nutrients provide energy and materials for cell development,
growth, and repair.
b. You need energy for every activity your body performs.
B. Classes of nutrients.
a. Proteins.
i. Used for replacement and repair of body cells and for
growth.
ii. Made up of amino acids—building blocks for
proteins.
b. Carbohydrates
i. The main source of energy for your body.
ii. Sugars are simple carbohydrates; starch and fiber are
complex carbohydrates.
c. Fats
i. Provide energy and help your body absorb vitamins.
ii. Classified as unsaturated or saturated based on their
chemical structure.
iii. Unsaturated—are liquid at room temperature.
(Vegetable oil, seeds)
iv. Saturated—are usually solid at room temperature.
(Meats, animal products, and some plants)
d. Vitamins and minerals
i. Needed for growth, regulating body functions, and
preventing some diseases.
e. Water
i. The human body is 60% water.
ii. You lose water everyday when you perspire (sweat).
Exhale, and get rid of wastes.
C. Food Groups
a. Food pyramid helps people select foods that supply all the
nutrients they need.
b. Foods that contain the same nutrients belong to the same
food group.
c. Five food groups
i. Bread and cereal
ii. Vegetable
iii. Fruit
iv. Milk
v. Meat
Section 3 (pages 412-418)
I The respiratory system
A. Functions of the respiratory system
a. Supply oxygen to the body.
b. Breathing is the movement of the chest that brings air into
the lungs and removes waste gases.
c. Cellular respiration—is when oxygen is used by the cells to
release energy from glucose.
d. The waste products of cellular respiration are carbon dioxide
and water.
B. Organs of the respiratory system
a. Pharynx—a tube-like passageway used by food, liquid, and
air.
b. Larynx—where air passes through and contains the vocal
cords used to speak.
c. Trachea—tube held open by rings of cartilage; lined with
cilia and mucous membranes.
d. Bronchi—found at the lower end of the trachea, they are two
small tubes that branch into smaller tubes.
e. Bronchioles—smallest tubes after bronchi.
f. Alveoli—Clusters of sacs that exchange of gases occurs.
i. They are surrounded by capillaries
C. Why do we breathe?
a. Signals from your brain tell muscles in your chest and
abdomen to contract and relax.
b. Diaphragm—muscle that contracts and relaxes to move gas
into and out of the lungs.
D. Diseases of the respiratory system
a. Colds, flu, and pneumonia
b. Chronic bronchitis—disease of alveoli, which enlarge and
fail to function effectively
c. Lung cancer—uncontrolled cell growth in lung tissue
d. Asthma—bronchial tubes contract quickly, causing
shortness of breath and wheezing.
SECTION 4 (PAGES 419-423)
I Functions of the excretory system
A. To remove wastes from the body.
B. Urinary system—gets rid of cell wastes in the blood and controls
blood volume
C. Organs of the urinary system
a. Nephrons—filtering units in kidneys that blood passes
through.
b. Bladder—holding tank for urine made in the kidneys
c. Ureters—tubes from the kidneys to the bladder that urine
passes through.
d. Urethra—tube that passes urine out of the body.
D. Urinary diseases and disorders.
a. Infections—often occur in the bladder and kidneys
b. Blocked urethra or ureter—damages kidneys
c. Kidney failure—If both kidneys fail, a person might need
dialysis or a transplant.
i. Dialysis—is a machine that filters the blood instead of
the kidneys.