Digestive System

What are the functions of the digestive system?

1. Mechanical digestion: chewing and mixing food 2. Chemical digestion: breaking down the

molecules in food, from big polymers into small monomers

3. Absorption: when nutrients are absorbed from food into the blood

Processing Piece:• These both happen in the mouth. Label them

“mechanical digestion” and “chemical digestion”.–Chewing food into smaller pieces– Salivary amylase breaks down starch into glucose

What organs does food travel through (or past) in the digestive system?

1) Mouth: Chews food to break it into smaller pieces. Enzymes like amylase begin chemically breaking down carbohydrates like starch.

2) Esophagus: a tube that connects the mouth to the stomach. It moves food by squeezing itself to push food down – this movement is called peristalsis.

What organs does food travel through in digestive system?

3) Stomach: a muscular, U-shaped organ where carbohydrates are broken down into monosaccharides and proteins are broken down into amino acids. - Stomach breaks down food using acid and digestive

enzymes like pepsin.- Half-digested food in the stomach is “chyme.”

What organs does food travel through in digestive system?

4) Small intestine: 70 foot long tube where digestion is completed. Lipids are broken down into fatty acids and glycerol, and absorption begins.- Small intestines are lined with “villi” which is where

nutrients are absorbed into the blood.5) Large intestines: large tube where water is absorbed into the blood6) Rectum: stores waste before it is expelled from the body.

Processing Piece:Try to label the structures we talked about.

How do villi work?

• Vill

How do villi work?• Villi are tiny, finger-like structures in the lining of the

small intestines.• Nutrients in the small intestine diffuse (spread out)

through the cells in the walls of the villi into the capillaries (tiny blood vessels) inside the villi.

Processing Piece:• Draw a picture of the villi. Label the capillaries, and

show which way the nutrients from food diffuse.

What other organs are involved in the digestive system?

1) Pancreas: organ that secretes (releases) digestive enzymes into the small intestines to help break down lipids.2) Gallbladder: organ that secretes (releases) bile (a soap-like chemical that breaks down fats) into the small intestines to help break down lipids.

Exit Ticket1. What is the function of the digestive system?2. Describe the path that food takes through the

body, from mouth to rectum.3. What part of the digestive system absorbs

nutrients?4. Draw a picture of a villi. Label the capillaries, and

draw an arrow to show which way nutrients go.