The digestive system is a long muscular tube into which glands secrete hydrolytic enzymes, chemicals to maintain the pH for the enzymes to work such as hydrochloric acid and sodium hydrogen carbonate and other substances such as bile to emulsify fats to aid their digestion.
The mouth is called the oral cavity. Salivary glands near the mouth secrete saliva into the mouth. Saliva has a pH of 7 and contains the enzyme salivary amylase which hydrolyses starch to maltose.The oesophagus is a long, muscular tube that pushes food from the mouth to the stomach through a muscular action called peristalsis.In the stomach, HCl produced by the gastric cells denatures the amylase. Gastric glands in the stomach secrete endopeptidases such as pepsin which hydrolyse proteins to shorter polypeptides.The duodenum is the start of the small intestine. The pancreas secretes exopeptidases, pancreatic lipase and pancreatic amylase in pancreatic juice which is alkaline and has a pH of 8.5. The liver produces bile and stores it in the gall bladder. During digestion bile is secreted into the duodenum. Bile salts emulsify fats.Absorption takes place in the ileum. Membrane-bound dipeptidases and maltase complete the digestive process. Glucose and amino-acids are absorbed into the capillaries in the villi and fatty acids and glycerol are absorbed into the lacteals.
The mouth is called the oral cavity. Salivary glands near the mouth secrete saliva into the mouth. Saliva has a pH of 7 and contains the enzyme salivary amylase which hydrolyses starch to maltose.The oesophagus is a long, muscular tube that pushes food from the mouth to the stomach through a muscular action called peristalsis.In the stomach, HCl produced by the gastric cells denatures the amylase. Gastric glands in the stomach secrete endopeptidases such as pepsin which hydrolyse proteins to shorter polypeptides.The duodenum is the start of the small intestine. The pancreas secretes exopeptidases, pancreatic lipase and pancreatic amylase in pancreatic juice which is alkaline and has a pH of 8.5. The liver produces bile and stores it in the gall bladder. During digestion bile is secreted into the duodenum. Bile salts emulsify fats.Absorption takes place in the ileum. Membrane-bound dipeptidases and maltase complete the digestive process. Glucose and amino-acids are absorbed into the capillaries in the villi and fatty acids and glycerol are absorbed into the lacteals.