Human Alimentary Canal

• Ingestion: taking substances (e.g. food, drink) into the body through the mouth.

  
• Egestion: passing out of food that has not been digested, as faeces, through the anus.

  
• Digestion: the break-down of large, insoluble food molecules into small, water soluble molecules using mechanical and chemical processes

  
• Mouth: contains teeth used for mechanical digestion, area where food is mixed with salivary amylase & where ingestion takes place

  
• Salivary glands: produce saliva which contains amylase and helps food slide down oesophagus

  
• Oesophagus: tube shaped organ which uses peristalsis to transport food from mouth to stomach

  
• Stomach: has sphincters to control movement into and also has pepsin (a protease) to break down proteins into peptides, it also kills bacteria with hydrochloric acid. They also have elastic walls.

  
• Small intestine = tube shaped organ composed of the Duodenum and the Ileum

  
• Duodenum: fats are emulsified by bile, and digested by pancreatic lipase to form fatty acids and glycerol. Pancreatic amylase and trypsin (a protease) break down starch and peptides into maltose and amino acids

  
• Ileum: Maltase breaks down maltose to glucose. This is where absorption takes place; adapted by having villi and microvilli.

  
• Pancreas: produces pancreatic juice which contains amylase, trypsin and lipase and hydrogencarbonate.

  
• Liver: produces bile, stores glucose as glycogen, interconverting them to keep glucose concentration constant. Also carries out interconversion of amino acids (transamination), deamination and removal of old red blood cells and storage of their iron. Also, site of breakdown of alcohol and other toxins.

  
• Gall bladder: stores bile from liver

  
• Bile: produced by liver and stored in gall bladder, its role is to emulsify fats, to increase surface area for the action of enzymes.

  
• Large intestine: tube shaped organ composed of two parts:

  • Colon: organ for absorption of minerals and vitamins, and reabsorbing water from waste to maintain body’s water levels
  • Rectum: where faeces are temporarily stored

  
• Anus: ring of muscle which controls when faeces is released.