ORGAN SYSTEM

Organ System



Organ System

The Digestive System

The organs involved in the digestion system are pharynx, esophagus, stomach, pancreas, duodenum, small intestine, descending colon, sigmoid, anus, rectum, appendix, cecum, ascending colon, transverse colon, gallbladder, liver, tooth and tongue.

Mechanical Digestion

Mechanical digestion starts after the intake of food with chewing of food into smaller particles. The salivary glands in mouth contain an enzyme that digests the food starch into tiny molecules. Peristalsis also takes place in mechanical digestion through which the food moves through the intestinal areas.

Chemical Digestion

The digestive enzymes are responsible for breaking molecules like fats, proteins, and carbohydrates into fine molecules which can then be used by cells through absorption.

The digestive enzymes responsible for chemical digestion are Nuclease, Protease, Collagenase, Lipase, Amylase, Elastase, Trypsin and Chymotrypsin.

Absorption and Transport of Nutrients

The small intestine has villi which are covered with microvilli and nutrients can be absorbed through it. These absorbed materials pass the mucosa into the blood.

Starch and sugar are carbohydrates which can be digested by breaking into smaller molecules. Starch is broken by enzymes from saliva and pancreas into maltose. An enzyme in the small intestine breaks the maltose into glucose molecules which provides energy to the body. Sugar is digested by an enzyme in the small intestine which digests sucrose into fructose and glucose. (Cavallo, p.625)

Protein molecules are broken into amino acids by a number of enzymes produced in the pancreas and in the lining of the intestine. Later, amino acid can be carried into the blood and later to all the parts of the body to form the walls and other cells.

Fat molecules provide energy to the body. Fatty acids and cholesterol are a result of bile acids which dissolve fat and let the enzymes from pancreas and intestine to break the huge fat molecules into simpler ones. ...