BiologyCode 5090
Human digestive system
What this topic asks you to be able to do
- Identify these main regions of the digestive system: the mouth, oesophagus, stomach, small intestine (duodenum and ileum) and large intestine (colon, rectum and anus), together with the salivary glands, pancreas, liver and gall bladder
- Explain why digestion has to happen before most foods can be absorbed
- Describe physical digestion as food being split into smaller bits, a process without chemical change to its molecules
- Describe chemical digestion as the process of reducing big molecules to smaller ones
- State that physical digestion enlarges the surface area of food available to enzymes acting during chemical digestion
- Identify the classes of human tooth present, namely incisors, canines, premolars and molars
- Describe how human teeth are built, limited to: pulp, nerves, dentine, enamel and cement, and understand that each tooth is embedded in the gum
- Describe the functions of each category of human tooth during the physical digestion of food
- Describe the job of each main region of the digestive system, limited to: the mouth, which carries out ingestion and physical digestion and where amylase chemically digests starch; the salivary glands, which secrete saliva containing amylase; the stomach, which carries out physical digestion and the chemical digestion of protein by protease, and whose gastric secretions contain hydrochloric acid; the small intestine (duodenum and ileum), where starch is chemically digested by amylase, maltose by maltase, protein by protease and lipids by lipase; the liver, which produces bile and stores glycogen; the gall bladder, which stores bile; the pancreas, which releases an alkaline secretion containing amylase, protease and lipase; the ileum and colon, where absorption happens; and the rectum and anus, where egestion takes place
- Describe what amylase, maltase, protease and lipase do, giving the substrates and end-products of each, limited to: amylase – starch broken down to maltose; maltase – maltose broken down to glucose; protease (trypsin and pepsin) – protein broken down to amino acids; lipase – lipids broken down to fatty acids and glycerol
- Describe the function of the stomach's hydrochloric acid, which is to kill bacteria that have been ingested
- Understand that the various proteases in the stomach as well as the duodenum operate optimally at distinct pH levels
- Outline the function of bile in emulsifying fats so as to enlarge the surface area available for lipase to chemically digest fat into fatty acids and glycerol
- Describe peristalsis as circular and longitudinal muscles contracting in waves, pushing food along the digestive system