digestive system
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how are the enzymes in the digestive system produced
by specialised cells in glands and gut lining
structure of digestive system (10)
mouth, oesophagus, stomach, liver, gall bladder, bile duct, pancreas, small intestine, large intestine, anus
what happens in the mouth
amylase in the saliva begin to digest starch
what is produced in the stomach
it secretes protease enzymes
what happens in the liver
secreted bile which neutralises stomach acids and emulsifies fat to tiny droplets
what happens through the bile duct
transports bile from liver to work in small intestine
what is produced in the pancreas
produces protease, carbohydrase and lipas enzymes and releases them to the small intestine
what happens in the small intestine
1) produces protease, carbohydrase and lipase enzymes to complete digestion to glucose, amino acids, fatty acids + glycerol 2) where digested food is absorbed out of the digestive system and into the blood
what happens in the large intestine
absorbs excess water
name of how is food moved through the gut and explain
peristalsis 1) there’s muscular tissue all the way along the passage that food passes through during digestion 2) this squeezes balls of food (boluses) through the gut or it’ll get clogged up with bits of old food 3) squeezing action = waves of circular muscle contraction and relaxation is peristalsis
how are dissolved food and water absorbed in the digestive system
digestion produces soluble substances e.g glucose which is absorbed in the small intestine
what is the inside of the small intestine covered with
millions of tiny projections of villi
what is the main reason for villis quick absorption
increases surface area so soluble substances are quickly absorbed into the blood by diffusion
what is a reason that assists villis quick absorbtion
containing blood vessels = good blood supply so the soluble substances are taken away in the blood which helps maintain a steep diffusion gradient
what are 2 limitations of using visking tubing to model the gut
1) bad blood supply so it cant maintain a diffusion gradient from inside the tubing to the outside 2) visking tubing doesnt have any villi so the surface area is smaller