1. Section 38.2 The Digestive System
pp. 978 – 984

2. Why do we need to digest our food?
What is digestion?
Digestion is when our body converts food into simpler molecules (monomers).
Why do we need to digest our food?
Makes absorption of nutrients easier.
Makes it easier for our cells to use the nutrients

3. There are 2 Kinds of Digestion
MECHANICAL DIGESTION
PURPOSE: Break the food into smaller pieces (a physical change)
PROCESS: Chewing, churning, and mixing
PLACE: In the mouth and stomach ONLY
CHEMICAL DIGESTION
PURPOSE: Breaks the food into it’s monomers (a chemical change)
PROCESS: Enzymes and other compounds change the form of the food by chemical reactions
PLACE: In the mouth, stomach, and small intestines ONLY

5. Stop #1 Mouth FUNCTION: PROCESS MECHANICAL: Chew and mix the food
CHEMICAL: Break down starches (carbohydrates)
PROCESS
Teeth chew and mix the food
Enzyme called AMYLASE from the salivary glands breaks starches down into sugars

6. Stop #2 the Esophagus FUNCTION:
Moves food from the mouth to the stomach.
PROCESS:
Muscular contractions move the food down the the esophagus.

7. Stop #3 the Stomach FUNCTION: PROCESS
MECHANICAL: Churn and mix the food
CHEMICAL: Break down proteins
PROCESS
Muscles churn and mix the food
Enzyme called PEPSIN is released from stomach cells to digest proteins into amino acids. Hydrochloric acid helps pepsin to function properly.

8. Stop #4 the Small Intestines
FUNCTION:
CHEMICAL: Break down proteins, carbohydrates and lipids
ABSORPTION of nutrients
PROCESS
Enzymes are released from the small intestine, pancreas, and liver to aid in digestions of ALL nutrients
Villi are small folded projections in the small intestines that allow for more surface area for nutrient absorption

9. Accessory Organs to Digestion
Pancreas
FUNCTION: Makes enzymes for digestion carbohydrates, lipids, and proteins
PROCESS: Releases enzymes into the small intestine for digestion
Liver/Gall Bladder
FUNCTION: Makes bile for digestion of lipids
PROCESS: Bile is made in the liver and stored in the gall bladder. The gall bladder releases bile into the small intestines for digestion

10. Stop #5 the Large Intestine
FUNCTION:
ABSORPTION of water
ELIMINATION of remaining material
PROCESS
Water is absorbed through the walls of the large intestine.
Muscle contractions compact and eliminate the remaining material

11. Table of Nutrient Digestion and Organs
Chemical Digestion
Mechanical Digestion
Mouth
Starches with amylase from saliva
Chewing
Esophagus NO
Stomach
Proteins with hydrochloric acid (HCl) and pepsin
Churning
Small Intestines
Carbs, proteins, and fats with enzymes from the pancreas; fats with bile from liver
Large intestines