essays in biology

As the food enters the mouth starch is broken down to maltose by enzyme amylase found in the saliva,also saliva contains mucus that lubricate food for easy swallowing and water that softens food for easy chewing. The starch free food is swallowed down the gullet/oesophagus that contain muscles that contract and relax aiding peristalsis,it also contains goblet cells that produce mucus that in the digestion process it also aids peristalsis .When the food reaches the stomach through the cardiac sphincter, digestion of starch stops because the hydrochloric acid in the stomach deactivates enzyme amylase. Digestion of proteins starts in stomach in the presence of pancreatic juices,renin breaks caseinogen into curds/caesin and pepsin breaks all proteins into peptides.At this stage food has been broken down to chyme the it the stomach through the pyloric sphincter as it enter the duodenum where emulsification takes place,bile juice from the liver contains bile salts that neutralizes the acidic chyme and also it's the cause of emulsification. Finally the chyle enters the small intestine for absorption.the small intestine is long,coiled and narrow so as to increase the surface area for absorption of food. the undigested food reaches the rectum through the large intestine for egestion.