Download Digestive System

Digestive System
***Also known as the Alimentary Canal
A.
Function:
 Consists of organ and enzymes that break down food
and nutrients small enough to be absorbed by the
circulatory system by way of diffusion
B.
Types of Digestion:
C.
1.
Mechanical:
 Using teeth or muscle contraction to tear food
into smaller pieces
2.
Chemical:
 Using enzymes and fluid to digest food
Structures:
1.
Mouth:
 Mechanical: teeth and tongue tear and
manipulate food
 Chemical: saliva moistens food (+ H2O);
salivary amylase (enzyme that begins the
digestion of carbohydrates)
2.
Esophagus:
 Tube that connects the mouth with the stomach
 Peristalsis: muscular contraction of the
esophagus that moves food to the stomach
3.
Stomach:
 J-shaped muscular pouch
 Mechanical: contracts to churn the food and
fluids forming chyme (paste)
 Chemical:
a. mucous is released to protect the
stomach
b. pepsin: breaks down proteins
c. HCl: activates pepsin
d. Protease: digests proteins
4.
Small Intestine:
 Long tube that absorbs nutrients
 Nutrients diffuse from the digestive system to
the circulatory system
 Villi: finger-like projections (folds in the small
intestine) surround by blood vessels that allow
diffusion of nutrients to the circulatory system
5.
Accessory Organs:
 Pancreas: add enzymes to digest food
 Liver: produces bile that emulsifies (dissolves)
fat
 Gallbladder: stores bile
6.
Large Intestine:
 Absorbs water by diffusion into the circulatory
system
 Moves waste materials outside the body
D.
Disorders/Problems:
1.
Acid Reflux:
 Overproduction of stomach acid that moves up
into the esophagus causing a buring sensation
2.
Ulcer:
 Open wound in the digestive tract caused by
overproduction of acid
3.
Cancer:
 Tumor formed in the digestive tract that may
limit the absorption of nutrient or water