DIGESTION PROCESS 1. Mouth and buccal cavity Mouth open into buccal cavity. It has muscular tongue which helps in ingestion of food. It has two jaws with four types of teeths, in buccal cavity. Saliva contain an enzyme salivary amylass or ptyalin which convert starch into sugar. starch------------------------->sugar
2. OESOPHAGUS Buccal cavity open into long tabular muscular structure through funnel shaped pharynx. No digestion occur in it. The lining of alimentary canal has muscles that contract rythmically in order to push the food forward. This movement is known as PERISTALTIC movement, it occurs all along the gut.
3. STOMACH Food passes to j-shaped stomach. It has branched tubular glands present in it’s wall which secrets gastric juices containing hydrochloric acid(HCL) , mucus, protein digestive enzyme (pepsin) and gastric lipase.
3.1 FUNCTION OF HCL It makes the medium acidic for proper functioning of pepsin. Pepsin get activated by HCL. HCL stops the functioning of salivary amylass. It kills the germs or bacteria to disinfect food.
3.2 FUNCTION OF MUCUS Mucus protect the inner lining of stomach from the acid and enzyme. 3.3 FUNCTION OF ENZYME In acidic medium pepsin act on protein and convert it in simpler forms like peptones and pepteosis. Gastric lipase convert a little amount of fat into fatty acids and glycerols.
4. SPHINCTER MUSCLES Sphincter muscles regulate the passage of food from stomach to small intestine. These are present at the base of stomach and ir regulated by contraction and expansion.
5. SMALL INTESTINE It is the longest part of the alimentary canal. It’s proximal or the interior part receives the secretions from the liver and the pancreas.
5.1 LIVER It is the largest gland which secrets bile juice which is stored in gall bladder. Further secretions of the bile juice passes from gall bladder to small intestine. Bile juice emulsify the fat (convert large globule of fat to small globule of fat) to facilitate the enzyme action efficiently.
6. INTESTINAL GLANDS These glands are present in the wall of small intestine which secrets intestinal juice or succus entericus. It contain number of enzymes which complete the digestion of food. Thus, the small intestine is the site of complete digestion of food where proteins are finally converted into amino acids, complex carbohydrates into glucose and fats into fatty acids and glycerols. The posterior or the distal part take part in the absorption of digested food. For this the inner lining of small intestine has numerous finger like projection called villi, which are rich in blood vessels thus increase the surface area for absorption of digested food. The blood vessels absorbs the digested food and passes it to each and part where it is utilize to produce the energy (assimilation), building up of new tissues and repair of old tissues.
7. LARGE INTESTINE Undigested food along with the large amount of water passes to large intestine. Here extra amount of water is absorbed by the wall of large intestine and remaining food passes to rectum.
8. RECTUM & ANUS Undigested food is collected as faces in the rectum. Rectal wall also absorbs some water from it and faccal matter is egested out from the anus. It is regulated by sphincter muscles.