exchange and trasnport Flashcards
the digestive system glands
produce enzymes that hydrolyse large molecules into smaller one ready for absorption
what does diesgtive system do
exchange surface through which food substances are absorbed
physical breakdown
teeth and muscle of stomach wall
chemical digestion
carried out by enzymes by process of hydrolysis eg. splitting up of molecules by adding of water to chemical bond
what is needed to hydrolyse a large molecule
more than one enzyme
starch diesgtion
amylase proudced in mouth
and pancreas
amylase hydrolyses the alternate glycosidic bond of starch to form disaccharide maltose . saliva also contains mineral salts so ph is neutral
2) maltose then hydrolysed into monosaccharide alpha glucose by another enzyme, maltase produced in lining of ileum
maltase is part of cell surface membrane od epithelial cell that line ileum eg. membrane bound disaccharides
sucrose
sucrase hydrolyses glycoside bond in this molecule to form 2 monosaccharides , glucose and fructose
lactose
lactase hydrolyses glycosidic bond in this molecules to form 2 minosaccharides, glucose and galactose
what proteins an=re sucrose and lactose
extrinsic protein on the cell surface membrane of the epithelial cells of the small intestine
endopeptidase
hydrolyse the peptide bond between amino acids in central region of a protein forming a series of peptide molecules
produces more ends
exopeptidase
hydrolyse the peptide bond on terminal amino acids of peptide molecule formed by the endopeptidase thus realising dipeptides and single amino acids
dipeptidases
hydrolyse the bond two amino acids of a dipeptide
dipeptidases are membrane e bound forming a part of cell surface membrane of epithelial cells lining the ileum
the ileum
long muscular tube where food digested by enzymes
inner walls fold into villi large sa vol increased by microvilli on epithelial cell of each villus
purpose to absorb products of diesgtion into blood streamXDD
lipid digestion
1)fatty acids and triglycerides are emulsified by bile salts to form micelles
2)fatty acids enter the epithelial cells and link to form triglyericdes
3)triglycerides combine with proteins inside the Golgi body to form chylomicrons
4)chylomicrons enter the lacteal and are transported away from the intestine
what happened to lipids after entering epithelial cells
1)monoglycerides and fatty acids diffuse through the phospholipid bilayer into the eptheilail cell of the small intestine
2)move to smooth endoplasmic reticulum
3)trigllycerised reformed
4)pass to Golgi apparatus
5)starting in SER and completed in Golgi apparatus they associate with cholesterol and lipoproteins to form chylomicrons
