NME 2.12 Flashcards
describe digestion and absorption of lipids
- lipid emulsion
- allow pancreatic lipase to act on the lipid and digest it
- micelles get in beteen microvilli
- aggregated triglycerides form chylomicrons
what are dietary lipid
- triester of glycerol and long chain fatty acid
- phospholipids
what does the dietary lipid substitute?
- substitute 1 fatty chain with phosphor ester organic base
which glycerol lipase cannot act on?
2nd glycerol
what does co-lipase cleaves and cause?
- 1 and 3 linkages
- remove 2 fatty acid and 2 mono-glyceride
- isomerisation of 2 monoglyceride to 1 monoglyceride
what causes the isomerisation of 2 monoglyceride?
- fatty acid on one part of teh glyceride will flip
what does polar groups of bile salts impart on micelles?
- negative charge on the surface
what does negative charges on micelles do?
- keep stable suspension
- mutual repulsion between micelles
how does the composition of micelles changes down the small intestine
- content of fatty acid and monoacylglycerol diminishes while their proportional content of bile acid increases
what deos the micelles have to diffuse across?
- unstirred layer to the enterocyte cell membrane
what kind of micelles carry lipids through acidic unstirred layer?
- mixed micelles
what leaves the mixed micelles and enter acidic microenvironment?
- 2-MAG
- fatty acid
- lysophospholipids
- cholestrol
how does lipid enter enterocyte?
- nonionic diffusion
- incorporation into enterocyte membrane through collision
- carrier mediated transport
which process of lipid digestion and absorption is rate limiting?
- lipid uptake
what causes the acidic microclimate?
- proton exchanger
how to make lipid easier to absorb?
- protonated which make it not charged and easier to absorbed
what aids transport of cholestrol during absorption?
- neimann-pick C1 like-1
what helps with absorption of fatty acid?
- fatty acid translocase
- fatty acid transport protein subtype 4
what drives lipid uptake?
- re-esterification of fatty acid
what does triglyceride resynthesis do?
- maintain diffusion gradient
- re-esterification of long chain fatty acids
- triglycerides transferred to chylomicrons and VLDL
- short and medium fatty acid go to portal circulation binding on albumin
where in the cell does triglyceride re-synthesis occurs?
smooth endoplasmic reticulum
where does the chylomicrons go?
- lacteals which will bypass the liver
how is phospholipid synthesized by?
- esterification of lysophospholipid with fatty acyl-S-CoA
how is cholesterol synthesized by?
- free cholesterol and fatty acyl-S-CoA
what happens during lipid malabsorption?
- fatty stools
what causes lipid malabsorption?
- pancreatic deficiency
- bile acid deficiency
- chylomicrons formation deficiency
- lymphatic deficiency
- drugs which interfere with lipid absorption
