mass transport Flashcards
what is digestion?
the breakdown of large insoluble molecules into smaller more soluble molecules
What does the enzyme amylase do?
catalyses the breakdown of starch into molecules into maltose
where do amylase and other carbohydrases get produced?
- salivary glands
- pancreas
- small intestine
what are membrane bound disaccharides?
enzymes that are attached to the cell membrane of epithelial cells lining the ileum
what do membrane bound disaccharides do?
help breakdown disaccharides into monosaccharides via the hydrolysis of glycosidic bonds.
what is sucrose hydrolysed into and what enzyme catalyses this reaction?
- sucrose = glucose + fructose
- sucrase
what is maltose hydrolysed into and what enzyme catalyses this reaction?
- maltose = glucose + glucose
- maltase
what is lactose hydrolysed into and what enzyme catalyses this reaction?
- lactose = glucose + galactose
- lactase
what do lipids get hydrolysed into?
fatty acids and glycerol
where are lipases secreted?
- pancreas
- small intestine
where are by salts produced and what do they do?
- produced in the liver
- they emulsify lipids into smaller droplets
are bile salts enzymes?
no but they increase the surface area as they produce smaller droplets for the lipases to work on.
what happens when monoglycerides and fatty acids stick together with bile salts?
they form micelles
what do micelles do?
they help the products of lipid digestion to be absorbed
what are micelles the product of?
monoglycerides + fatty acid + bile salts
what is the name of the enzymes that catalyse the breakdown of proteins into amino acids?
proteases / peptidases
what do endopeptidases do?
hydrolyse peptide bonds within a protein
what do exopeptidases do?
hydrolyse peptide bonds at the end of proteins (remove single amino acids)
what do dipeptidases do?
work specifically on dipeptides
where are dipeptides located?
they are often located in the cell surface membrane of epithelial cells and are membrane bound
what happens to the products of digestion?
the products of digestion are absorbed across the ileum epithelium into the bloodstream
how is glucose absorbed into the bloodstream?
by active transport with sodium ions via a co-transporter protein
how is galactose absorbed into the bloodstream?
by active transport with sodium ions via a co-transporter protein
how is fructose absorbed into the bloodstream?
by facilitated diffusion through a carrier protein
how do micelles allow the products of lipid digestion to be absorbed?
- they help to move monoglycerides and fatty acids towards the epithelium
- micelles constantly break and reform , they can ‘release’ monoglycerides ad fatty acids to be absorbed.
- they are lipid soluble and so diffuse directly across the epithelium membrane.
how are amino acids absorbed into the bloodstream?
- by active transport
- via sodium-dependant transporter proteins
- sodium carries amino acids with it
