Download THE DIGESTIVE SYSTEM

THE DIGESTIVE SYSTEM
The Functions of the Digestive System:
1) Breaks down food into molecules the body can use.
2) The molecules are absorbed into the blood stream and carried
throughout the body
3) Wastes are eliminated from the body.
*The human Digestive System is an Alimentary Canal – which means it
has two openings.
THE MOUTH
*Mechanical and Chemical digestion begin in the mouth.
1) Mechanical Digestion: The teeth tear and slash food into
smaller pieces.
2) Chemical Digestion: Saliva begins to break down food into
smaller molecules.
3) Enzymes in the saliva help with the chemical break down of
molecules.
THE ESOPHAGUS
*A muscular tube connecting the Mouth to the Stomach.
1) Epiglottis – Flap of skin that covers the windpipe when you
swallow food.
2) Peristalsis – involuntary contractions of the muscles of the
Esophagus. Also occurs in the Stomach and Intestines.
THE STOMACH
*J shaped muscular pouch.
1) Responsible for most mechanical digestion and some chemical
digestion.
a) Mechanical digestion happens by the churning action of
the stomach.
b) For chemical digestion, stomach produces the enzyme
Pepsin in hydrochloric acid solution.
c) Mucus lining of stomach prevents acidic digestive juices
from harming the stomach.
2) Stomach breaks down food into liquid form called Chyme. The
Chyme moves to the next section for final digestion.
THE SMALL INTESTINE
1) Most chemical digestion and absorption of nutrients occur in
the Small Intestine.
2) The Liver produces Bile, which breaks down fats.
3) The Liver sends Bile to the Gall Bladder, which stores the Bile.
4) The Gall Bladder releases the Bile into the Small Intestine
(Duodenum) to break up fats in foods.
5) The smaller droplets of fat are digested by enzymes.
6) The Pancreas produces enzymes that break down starches,
proteins and fats. It releases its enzymes into the Small
Intestine.
7) Absorption occurs through fingerlike projections called Villi.
8) The Villi increase the surface area of the Small Intestine.
THE LARGE INTESTINE
1) Last part of the digestive system.
2) Water is absorbed into the bloodstream.
3) Bacteria feed from the undigested food, producing some
vitamins.
4) The Large Intestine ends in a short tube called the Rectum,
where the waste is compressed into solid form (called feces).
5) The waste goes out of the body through a muscular opening at
the end of the Rectum called the Anus.