A hamburger is composed of two main components, namely, bread and meat.
These parts can be broken down into different component groups. Although both.
substances contain all four food groups, the bread accounts mainly for.
carbohydrates and cellulose (roughage), whilst the meat mainly accounts for.
proteins and lipids. Before the hamburger can be absorbed and used by the body,.
it firstly has to be broken down into small molecules, which can then pass into.
the blood or lymph stream.
A piece of the hamburger is bitten off by the teeth. The teeth tear and grind the.
hamburger, with the aid of the tongue, which positions the food between the teeth.
and mixes it with saliva. Mastication breaks the food into smaller pieces,.
enlarging the surface area for better enzyme action. The digestive enzyme.
amylase, is found in the saliva, which in turn is produced in the mouth. The.
amylase starts to digest the polysaccharide, starch (carbohydrate), before the.
food is swallowed. The hamburger has now entered the alimentary canal.
The hamburger now moves through the oesophagus, by means of peristalsis, and.
through the cardiac sphincter into the stomach. It will remain here for between 1.
and 2 hours. It is now broken still into smaller pieces by the churning of the.
stomach. The secretion of the hormone, gastrin, is stimulated by the presence of.
food. It in turn stimulates the secretion of hydrochloric acid (HCl) and pepsin.
The very acidic gastric juice is secreted by gastric glands inside the stomach. The.
acidic nature is due to HCl, which is secreted by oxyntic cells. The HCl activates.
the enzyme pepsin from its inactive form, pepsinogen, in the stomach. Pepsin.
hydrolyses the proteins into large polypeptides. The HCl also destroys most.
ingested bacteria. Mucus is secreted to ease the passage of the hamburger. The.
substance in the stomach is now called chyme.
Chyme is a soup-like substance. It is released into the small intestine, by the.
