Combined ScienceCode 5129
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), as well as the salivary glands, pancreas and liver
- Explain why the majority of foods must be digested before absorption is possible
- Describe physical digestion: food is broken up into smaller pieces, without the molecules in it being changed chemically
- State that physical digestion gives food a larger surface area for enzymes to act on during chemical digestion
- Describe chemical digestion as the process in which large molecules are broken down to give small molecules
- Describe what each main region of the digestive system does, limited to: (a) mouth – ingestion, physical digestion, and amylase digesting starch chemically (b) salivary glands – producing saliva, which contains amylase (c) stomach – physical digestion, protease digesting protein chemically, and hydrochloric acid in the gastric secretions (d) small intestine (duodenum and ileum) – chemical digestion in which amylase acts on starch, maltase on maltose, protease on protein and lipase on lipids (e) liver – storing glycogen, and breaking down excess amino acids to form urea, which the kidneys excrete (f) pancreas – an alkaline secretion that contains amylase, protease and lipase (g) ileum and colon – where absorption takes place (h) rectum and anus – where egestion takes place
- Describe the function of each of the enzymes amylase, maltase, protease and lipase, naming the substrates and products, limited to: (a) starch is broken down to maltose by amylase (b) maltose is broken down to glucose by maltase (c) protein is broken down to amino acids by protease (d) lipids are broken down to fatty acids and glycerol by lipase
- Describe the function of the stomach's hydrochloric acid: it kills bacteria that have been ingested
- Understand that the stomach and the duodenum contain different proteases, and that each of them has a different pH at which it works best