Recognise the structures of the human alimentary canal (digestive system) and describe in outline the functions of the mouth, oesphagus, stomach, small intestine and pancreas.
Food is introduced into the digestive system through the tongue and mouth, this is a process known as ingestion. Teeth helps to break food down so we can swallow, and we call this process chewing. We also have the addition of mucus which lubricates the food and helps the food to slide down through the digestive system. We begin with the addition of salivary amylase which is an enzyme which breaks down starches.
The oesphagus is a tube which carries food from the mouth to the stomach in which there is no digestion. The food moves down the tube with a process called peristalsis.
The food is then stored in the stomach, and also in the stomach there will be acid which kills off the bacteria in the food. Another feature of the stomach is the presence of a group of enzymes known as proteases. These enzyme begin the digestion of protein.
As the food then moves from the stomach to the small intestine, there is an addition of enzymes from the pancreas. These enzymes will bring about the complete breakdown of the food so that it can be absorbed in the small intestine.
The liver has a structure which manufactures bile and is stored in the gall bladder. The bile neutralises the stomach acid so that the ph in the small intestine is roughly 7 and emulsifies (breaks down into small droplets) the fat in out diet.
The function of the small intestine is the absorption of nutrients into our bloodstream, after that the food travels from the small intestine into the large intestine [colon]. This is where we absorb water into out bloodstream. Finally, the food in which we cannot digest is stored in the rectum and then released from the anus.