digestion and absorption 2 Flashcards
what are lipids broken down by
lipase (with the help of bile salts)
what aids in lipid break down
bile salts
what do lipases do
lipase enzyme catalyse the breakdown of lipids into monoglycerides and fatty acids involving the hydrolysis of ester bonds in lipids
where are lipases made and where do they work
lipases are made in the pancreas and work in the small intestine
where are bile salts produced
the liver
what do bile salts do
they emulsify lipids they cause the lipids to form small droplets
why is it essential several lipid droplets are formed from lipids
as several lipid droplets greatly increases the surface area of lipid that’s available for lipase to work on
what happens after the lipid has been broken down
monoglycerides and fatty acids stick with the bile salts to form tiny structures called micelles
what are proteins broken down by
endo peptidases and exo peptidases
what do endopeptidases do
they act to hydrolyse peptide bonds within a protein
what are two examples of endopeptidases
trypsin and chromotrypisin
where are endopeptidases synthesised
the pancreas and secreted into the small intestine
where are endopeptidases secreted
the small intestines
what is pepsin and where is it released into
it is another endopeptidase and is released into the stomach
which cells release pepsin
cells in the stomach lining
what type of conditions does pepsin work in
acidic condition
what provides acidic conditions for pepsin
hydrochloric acid in the stomach
what do exopeptidases do
they act to hydrolyse peptide bonds at the end of protein molecules
what do exopeptidases remove from proteins
single amino acids
what are dipeptidases
exopeptidases that work specifically on dipeptides. They act to separate the two amino acids that make up a dipeptide by hydrolysing the peptide bond between them
where are dipeptides often located
in the cell surface membrane of epithelial cells in the small intestine
where are the products of digestion absorbed
across the ileum epithelium into the bloodstream
how is glucose absorbed
glucose is absorbed by active transport with sodium ions via a co transporter protein
how is galactose absorbed
the same way as glucose using the same transporter proteins
how is fructose absorbed
via facilitated diffusion through a different transporter protein
what do micelles do
help to move monoglycerides and fatty acids towards the epithelium
due to the micelles constantly breaking up and reforming what can they do
they can release monoglycerides and fatty acids allowing them to be reabsorbed, whole micelles are not taken up across the epithelium
monoglycerides anf=d fatty acids are lipid soluble, what does this mean they can do
diffues directly across the epithelial cell membrane
how are amino acids absorbed
via co transport a similar way to glucose and galactose
because sodium ions are actively transported out of the ileum epithelial cells into the blood what does this result in
this creates a sodium ion concentration gradient
how do sodium ions exit the ileum epithelial cells
active transport
how do sodium ions diffuse from the lumen of the ileums int othe epithelial cells
through sodium-dependent transporter proteins, carrying the amino acids with them
