Digestion and absorbtion Flashcards
what is digestion?
the process in which large biological molecules are hydrolysed by enzymes to produce smaller molecules that can be absorbed across cell membranes and assimilated
what does the digestive system consist of?
the gut/alimentary canal and associated glands
what are the three enzymes in digestion?
amylase protease lipase
where is amylase produced?
salivary glands and pancreas
where is protease produced?
stomach and pancreas
where is lipase produced?
pancreas
what does amylase break down?
starch into maltose
what does protease break down?
proteins into amino acids
what does lipase break down?
lipids into fatty acids and glycerol
what part of the body do these enzyme reactions occur
A- mouth/small intestines P-stomach/small intestines L-small ontestines
explain the process of food and what happens in these stages?
stage 1-injestion - food taken in from mouth
stage 2- digestion - enzymes break large insoluble molecules into smaller soluble ones
stage 3 - absorbtion - the products of digestion are absorbed through the lining of the intestines
stage 4 - egestion - removal of faeces containing undigested food, bacteria, enzymes etc
explain carbohydrate digestion?
starch is hydrolysed by amylase into maltose. then maltose is hydrolysed by maltase into glucose
explain how is glucose absorbed?
via co-transport
explain protein digestion?
protein hydrolysed by endopeptidase into smaller polypeptides then hydrolysed by exopeptidases into dipeptides which are broken down by dipeptidases into amino acids
why can we not use endopeptidase to break down smaller polypeptides aswell?
endopeptidase only breaks the bonds within the polypeptide so will take a very long time to break fully
exopeptidases hydrolyse..?
peptide bonds at the end of a protein removing single amino acids
explain how amino acids are absorbed?
by co-transport
explain the digestion of lipid?
lipids are hydrolysed by bile slats into emulsified lipids which are hydrolysed by lipase into fatty acids + glycerol+ monoglycerides
explain how lipids are absorbed?
- lipids are broke down into emulsified droplets by bile salts Which is then hydrolyses by lipase into micelles
- micelles and come into contact with epithelial cells and break down and release the monoglycerides and fatty acids
- (high concentration of micelles outside of epithelial cells and a low concentration inside epithelial cells) diffuse into the epithelial cells
- where they form triglycerides in the (smooth) ER.
- triglycerides combine with proteins in the golgi body to form chylomicrons.
- chylomicrons move out of epithelial cells by exocytosis and enter the lacteal where they are transported.
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