Transcript Chapter 18 The Digestive System Ch 18.1 - Nutrition A. Your body needs nutrients found in foods 1.

Chapter 18
The Digestive System
Ch 18.1 - Nutrition
A. Your body needs nutrients found in foods
1. Nutrients provide energy and materials
for cell development
2. You need energy for every activity and
to maintain a steady internal temperature
B. Classes of Nutrients
1. Proteins
a) Used for replacement and repair of
body cells and for growth
b) Made up of amino acids
c) Essential amino acids supplied by food
d) Found in eggs, milk, cheese and meat
2. Carbohydrates
a) Main source of energy for your body
b) Made of carbon, hydrogen and oxygen
c) Sugars are simple; starch & fiber complex
- Sugars found in fruits, honey, milk
- Starches found in potatoes and pasta
- Fiber found in whole-grains and veggies
3. Fats
a) Also called lipids
b) Stores excess energy
c) Helps body absorb vitamins
d) Classified as saturated & unsaturated
- Saturated solid at room temp, clog blood
vessels and associated with high cholesterol
- Unsaturated liquid at room temp, and not
associated with health risks
4. Vitamins
a) Needed for growth, regulating body
functions and preventing disease
b) A well-balanced diet usually gives your
body all the vitamins it needs
c) Two groups: water soluble & fat soluble
- Water: Vitamins B & C
- Fat: Vitamins A, D, E & K
5. Minerals
a) Inorganic nutrients needed in small
amounts
b) Regulate many chemical reactions in
the body
c) Calcium and Phosphorus used most
6. Water
a) Required for survival
b) Cells need water to carry out their work
c) Dissolves other nutrients
d) Human body is about 60% water
e) Lost each day when you perspire,
exhale, and get rid of wastes
C. Food Groups
1. Because no food has every nutrient you
need to eat a variety of foods
2. The food pyramid is a tool to help
people select foods that supply all the
nutrients they need
3. Foods that contain the same nutrients
belong to a food group
4. Five food groups:
a) Bread and Cereal
b) Fruit
c) Vegetable
d) Dairy
e) Meat, Poultry, Fish & Beans
Ch 18.2 – Digestive System
A. Digestion – process of breaking down
food into small molecules to be absorbed
1. Mechanical Digestion – when food is
physically chewed, mixed and churned
2. Chemical Digestion – when food is
broken down by chemical reactions
B. Enzymes
1. Type of protein that speeds up rate of
chemical reactions in your body
2. Many enzymes are involved in the
digestion of carbs, proteins and fats
C. Organs of the digestive system
1. Accessory organs – aid in digestion but
food does not pass through them
a) tongue, teeth & salivary glands
b) Liver – produces bile for the stomach
which breaks up ingested fats
c) Gallbladder – small sac that stores bile
produced by the liver
d) Pancreas – produces insulin which allows
the body to process carbohydrates (sugars)
2. Digestive Tract – organs that food does
pass through during digestion
a) Mouth – here accessory organs change
food into a soft mass called a bolus
b) Esophagus – muscular tube that moves
food to the stomach using waves of
muscle contractions called peristalsis
c) Stomach – muscular bag that digests
food mechanically by peristalsis and
chemically with digestive solutions of HCl
acid; food becomes a thin, watery fluid
called chyme
d) Small Intestine – nutrients are absorbed
from chyme into the blood; projections
called villi increase surface area for
absorption
e) Large Intestine – water absorbed from
undigested chyme; peristalsis slows so
chyme may remain here as long as 3 days
f) Rectum & Anus – end of large intestine
and opening to outside of body; controls
release of remaining solid wastes
D. Bacteria live in many organs of the
digestive tract helping to break down food
and make vitamins
ESCHERICHIA COLI is a type of bacteria that lives in the intestinal tract, aiding the digestive process by
suppressing the growth of harmful bacteria and synthesizing vitamins.