Case 3 - Fat absorption Flashcards
what is fat absorption dependent on
dependent on bile salts (acids)
what do the bile salts do
emulsification of large fat droplets (increased surface area for action of lipase)
formation of mixed micelles = stabilises products of triglyceride hydrolysis (MG + FA) while they are translocated to apical membrane
what does no bile result in
steatorrhea
describe simply diffusion of FA
limited with few FFAs in undissociated state (pKa around 4.9) this means that 50% will be in the dissociated form
describe the FFA transporters
FAT plus CD36 and potentially others
what are the transporters in the colon
SCFA
describe MG and FA absorption and TG re-synthesis
FA and MG are absorbed and then:
TG is re synthesised in ER, packaged in chylomicrons
exocytosis of the chylomicrons
chylomicrons transported in lymphatic system in the liver
where does cholesterol absorption happen
the duodenum
what is the protein that allows for cholesterol absorption
NPC1L1 protein
what kind of process is cholesterol absorption
receptor mediated endocytosis
what inhibits this endocytosis - therefore inhibiting cholesterol absorption
ezetimibe inhibits endocytosis = decreased plasma cholesterol
what are examples of short chain fatty acids
butyrate, propinate, acetate
how are SCFAs produced
by bacterial fermentation in the colon
what is the transporter used for short chain fatty acids and what are SCFAs largely used for
SMCT1 transporter takes the SCFA into the epithelial cells and they are largely used for intracellular metabolism
what increases the risk of metabolic diseases
propionate and acetate
