pre med - part 4

FOURTH WEEK

Second last week was not very hectic. We learnt about gastrointestinal tract or commonly called GI tract. Not so much new things, because we already learned this during our secondary school. Just a few adds here and there. The schedule for this week also was not packed compared to the second week. Probably because the lecturers wanted to give us time to study as we will sit on the exam on the week after. I want to share a few things that I learned before. GI tract is a continues tube-like tract in the body begins at mouth and ends at anus and its function is to digest food and absorbs nutrient essential for the body. Those which are nonessential is eliminated through a process called deafecation. Digestion mostly occurs in the small intestine. In order to digest food, there were lots of muscle movements(peristalsis and segmentation) and secretions (saliva, gastric juice, pancreatic juice, bile) occured. The movements and secretions are controlled by the nervous system and also endocrine system. Apparently, the muscle movements are all involuntary reaction. However, some secretions are controlled by nervous and some are controlled by the endocrine system due to hormone regulation. The most common hormones involve in this process are Cholecystokinin (CCK), secretin, Gastrin and Gastric Inhibitory Peptide hormone. CCK stimulates the secretion of pacreatic juice and the contraction af gall bladder. Secretin stimulate the production of bicarbonate ion (to neutralise the chyme). Gastrin enhances the secretion of pepsinogen and HCl in gastric juice also stimulate the growth of stomach cell. GIP inhibits the secretion of Gastric juice (when no food enters).