digestion and absorption Flashcards
what do amylases do?
hydrolyse starch into disaccharides like maltose
where are amylases produced?
salivary glands and the pancreas
where are membrane bound disaccharidases found?
in the cell membranes of epithelial cells in the elium
what do membrane bound disaccharidases do?
hydrolyse disaccharides into monosaccharides
what do endopeptidases do?
hydrolyse peptide bonds in the middle of the protein molecule
where are endopeptidases produced?
pancreas and stomach
what do exopeptidases do?
hydrolyse the final peptide bond on the ends of a chain
what do the exopeptidases break polypeptides into?
dipeptides
what do membrane bound dipeptidases do?
hydrolyse the bond between the last two amino acids do fully digest the peptide
how are amino acids absorbed into the lining of the ileum?
mostly co-transport
(some facilitated diffusion)
what adaptations do the villi have to make them effective at absorption?
rich blood supply - maintain a steep concentration gradient
microvilli - increase surface area even more
cell wall is one cell thick - ensure a short diffustion pathway
what happens in the physical breakdown of lipids?
bile (produced in the liver and stored in the gallbladder) emulifies lipids into micelles, increasing the surface area available for lipase to work on to enable a faster hydrolysis action
what happens in the chemical breakdown of lipids?
lipase enzyme hydrolyse the ester bonds between the fatty acids and the glycerol
what is produced after the hydrolysis of lipids?
fatty acids, glycerol molecule, some monogylcerides (when the fatty acid isnt broken down properly and there is 1 fatty acid left)
what carries the fatty acids towards the epithelium for absorption?
micelles
