bio test revision
digestion
breaking down large insoluble food molecules into small soluble ones. which can be absorbed into body cells
mouth - chewing (mastification?)- increase surface are for enzyme to act on
- amylase digest starch -> maltose
-tongue rolls food into bolus, is swallowed
oesophagus - smooth muscles cause rhythmic wave-like contractions (peristalsis), food passes down to stomach
stomach - gastric juice pH2 - churns food to mix well w/ gastric juice
hydrochloric acid - kills bacteria - stop action of amylase on starch - activates inactive enzmyes pepsinogen n prorennin
pepsin digest protein to polypeptides
rennin convert soluble milk protein (caseinogen) to insoluble milk protein (casein)
small intestine - bile - pancreatic juice - intestinal juice - neutralise acid + provide alkaline condition for enzymes to act - small finger-like projections called villi -> increase surface area for absorption
bile - produced in liver - stored in gall bladder - secreted thru bile duct - emulsifies fat -> increase surface area
pancreatic juice - amylase - lipase - trypsinogen
intestinal juice - enterokinase - lipase - maltase - erepsin- sucrase- lactase
starch --amylase-> maltose --maltase-> glucose
fat --lipase-> fatty acids + glycerol
trypsinogen --enterokinase-> trypsin
protein --trypsin-> polypeptide --erepsin-> amino acids
sucrose --sucrase-> glucose + fructose
lactose --lactase-> glucose + galactose
large intestine - absorb water + mineral salts - store undigested food temporarily
absorption-process where digested food materials are taken into body cells
assimilation - process where some of the absorbed food materials are converted to new protoplasm or provide energy
sugar -> liver --insulin (produced in pancreas)-> glycogen
