Digestive System

Digestion
Phases Include
Ingestion
Movement
Mechanical and Chemical Digestion
Absorption
Elimination

Digestion
Types
Mechanical (physical)
Chew
Tear
Grind
Mash
Mix
Chemical
Enzymatic reactions to improve digestion of
Carbohydrates
Proteins
Lipids

Digestive System Organization
Gastrointestinal (Gl) tract
Tube within a tube
Direct link/path between organs
Structures
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large Intestine
Rectum

Mouth
Teeth mechanically break down food into small pieces. Tongue mixes food with saliva (contains amylase, which helps break down starch).
Epiglottis is a flap-like structure at the back of the throat that closes over the trachea preventing food from entering it. It is located in the Pharynx.

Esophagus
Approximately 20 cm long.
Functions include:
Secrete mucus
Moves food from the throat to the stomach using muscle movement called peristalsis
If acid from the stomach gets in here that’s heartburn.
Mouth, Pharynx and Esophagus Video

Stomach
J-shaped muscular bag that stores the food you eat, breaks it down into tiny pieces.
Mixes food with Digestive Juices that contain enzymes to break down Proteins and Lipids.
Acid (HCl) in the stomach Kills Bacteria.
Food found in the stomach is called Chyme.

Small Intestine
Small intestines are roughly 7 meters long
Lining of intestine walls has finger-like projections called villi, to increase surface area.
The villi are covered in microvilli which further increases surface area for absorption.
Crash Course Review

Small Intestine
Nutrients from the food pass into the bloodstream through the small intestine walls.
Absorbs:
80% ingested water
Vitamins
Minerals
Carbohydrates
Proteins
Lipids
Secretes digestive enzymes

Large Intestine
About 1.5 meters long
Accepts what small intestines don’t absorb
Rectum (short term storage which holds feces before it is expelled).

Large Intestine
Functions
Bacterial digestion
Ferment carbohydrates
Absorbs more water
Concentrate wastes

Accessory Organs The Glands
Not part of the path of food, but play a critical role.
Include: Liver, gall bladder, and pancreas

Liver
Directly affects digestion by producing bile
Bile helps digest fat
filters out toxins and waste including drugs and alcohol and poisons.

Gall Bladder
Stores bile from the liver, releases it into the small intestine.
Fatty diets can cause gallstones

Pancreas
Produces digestive enzymes to digest fats, carbohydrates and proteins
Regulates blood sugar by producing insulin
Web Page Reinforcement Video

On a sheet of paper, write the name of each colored organ:
Green:
Red:
Pink:
Brown:
Purple:
Green:
Yellow:

How’d you do?
Green: Esophagus
Red: Stomach
Pink: Small Intestine
Brown: Large Intestine
Purple: Liver
Green: Gall Bladder
Yellow: Pancreas