Download The Digestive System

The Digestive System
Chapter 29

Think about sliding a warm, tasty slice of
cheese pizza into your mouth. You take a
bite, chew, and swallow. You probably
aren't saying to yourself, "There, I'm
providing my cells with nutrients."
However, that's exactly what you're doing.
But first, your digestive system must
disassemble the pizza into basic building
blocks that your cells can use.
Activity: Enzymes at Work
Chew the saltine cracker 25 times and
record the answers to the following
questions:
 1) Was there a change in the taste as you
chewed it? What was the change?
 2) What do you think caused the change
in the taste?

Nutrition
Ingestion
 Digestion
 Absorption
Elimination

Nutrition
 Ingestion
Food
 Digestion
Food-->Nutrients
 Absorption
Nutrients
Elimination
Waste
Macromolecules
Carbohydrates
 Proteins
 Fats
 Nucleic acids

CHEMISTRY OF DIGESTION

HYDROLYSIS: WATER AND ENZYMES
BREAK DOWN LARGER MOLECULES INTO
SMALLER UNITS
– PROTEINS TO AMINO ACIDS
– CARBOHYDRATES TO SINGLE SUGARS
– FATS TO 1 GLYCEROL AND 3 FATTY ACIDS
http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html
HYDROLYSIS

Human Digestion
Mechanical Digestion- Chops & grinds
food into smaller pieces
 Chemical Digestion- Breaks the
chemical bonds within macromolecule,
producing smaller subunits.

Alimentary tract
– Mouth
– Esophagus
– Stomach
– Small intestine
title
Accessory
Structures
– Salivary
glands
– Liver
• Duodenum
– Gall bladder
• Jejunum
– pancreas
• Ileum
– Lg. Intestine
• (appendix)
Online Activities

Phsuccessnet.com
– Activity 29.1
– Activity 29.2
Digestion Occurs in a Tube
Mouth
Mechanical Digestion (teeth/ tongue)
 Chemical Digestion

– Salivia– produces amylase
 Breaks down carbohydrates
Pharynx
Bolus of food travels down throat
 Epiglottis

Esophagus

Peristalsis pushes food down tube into
the stomach.
Stomach
Rugae
 Gastric juices (mucus, HCl, enzymes) meet
bolus.

– Proteins digested here.
Bolus --- Chyme
 Sphincters
 2-6 hours to empty

Small Intestine
Long & narrow
 Absorption of most
nutrients takes place
here.
 Duodenum
(breakdown of fats,
proteins, and carbs)
 Villi absorb nutrients.

Villi
Large Intestine (Colon)
Wide & short
 Water is absorbed into body.
 Feces- undigested waste leaves in 12-24
hours
 Appendix

Liver/ Gall Bladder
Bile breaks down fats in the duodonem.
 Liver makes bile.
 Gall bladder stores it.

Pancreas

Secretes pancreatic juices into duodonem.
– Neutralizes chyme.
– Breaks down carbs, proteins, and lipids.
Reteach

Describe what happens to the
carbohydrates in a piece of pizza as they
travel through the digestive system.