Area 1: Functions of each part in the human digestive system
Area 2: Digestion and absorption processes in the small intestine
Food in the mouth stimulates the salivary glands to secrete saliva. Saliva is mixed with the food and mucus in the saliva helps to soften the food. Saliva contains an enzyme called salivary amylase which digests starch to maltose. The tongue rolls the food into small spherical bolus and the boli are swallowed and passed into the oesophagus via the pharynx. Peristalsis in the walls of the oesophagus pushes each bolus of food down into the stomach. The presence of food in the stomach stimulates the gastric glands to secrete gastric juice into the stomach cavity. Peristalsis in the stomach churns and breaks up the food, while at the same time mixing the food well with gastric juice (a dilute concentration of hydrochloric acid, mucus and pepsin). The pepsin digests the proteins to polypeptides and the partially-digested food becomes liquefied, forming chyme. Chyme passes in small amounts into the duodenum where the pyloric sphincter relaxes and opens.
When chyme enters the small intestine, it stimulates the pancreas to secrete pancreatic juice, which contains the enzymes pancreatic amylase, trypsin and pancreatic lipase. The pancreatic juice passes through the pancreatic duct into the duodenum. The pancreatic amylase breaks down starch to form maltose, which is then broken down by maltase to form glucose.
Area 3: Role of enzymes in digestion
by Nicole, Lee Shien and Inez 🙂
Kwan, L. P., & Lam, E. Y. K. (2007). Textbook (G.C.E. “O” level biology matters). Singapore: Marshall Cavendish Education.
MedGuidance. Digestive system parts and functions. Retrieved October 10, 2016, from https://www.google.com.sg/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwje1Z79j9nPAhXINo8KHXe2AyoQjRwIBw&url=http%3A%2F%2Fwww.medguidance.com%2Fthread%2FDigestive-System-Parts-and-Functions.html&psig=AFQjCNEWjDSvWieFG6YAraOfGuPNG56hKw&ust=147649428296334