wk 3 6 Physiology of lipid digestion and absorption of Ca,Fe,vitamins Flashcards
ingested lipids compose of
fats/oils - triaglycerols
phospholipids
cholesterol/cholesterol esters
fatty acids
which type of lipids are insoluble/ poorly soluble
insoluble - cholesterol esters
poorly - triaglycerols/cholesterols
emulsification
break down of fats
occurs in mouth, stomach, small intestine
small lipid droplets are created in emulsification, they will try to recombine t/f
false
negatively charged - repel
what is found on the surface of lipids
ampiphatic coat
water phobic/philic areas
what is found in lipid coat
multiamellar - fatty acid soap, cholesterol, bile salt
uniamellar - bile salts
what mediates lipid digestion in stomach
gastric lipase
gastric phase of digestion only important for pancreatic insufficiency/infants
gastrin released causes secretion of
gastric lipase
t/f pepsin activates gastric lipase
false
gastric lipase inactivated in duodenum due to pancreatic lipase
what does gastric lipase break triglyceride down to
diglyceride + free fatty
what does free fatty acids stimulate release
of CCK
what is requires to digest lipids in duodenum
pancreatic lipase
bile salts
HCO3-
triglyceride - 2-monoacylglyceride + 2 free fatty acids by
pancreatic lipase
CCK causes secretion of
bile salts
purpose of bile salts
emulsify large lipids
what aspect causes lipids once emulsified to stay in small droplets
has a negative charge. so each small lipid will be negatively charged and repel from one another
failure of bile salt secretion leads to 2
steatorrhea
ADEK vitamin defiency (since lipid vitamins are not absorbed)
t/f lipid digestion only occurs at surface
true
bile salts increase surface area for attack by pancreatic lipase. but blocks access of enzyme to hydrophobic core. Which ampipathic polypeptide fies this problem
colipase
starts off as procolipase, trypsin activates
which structure stores lipids
mixed
hydrophobic core - containing TAG/esterified cholesterol
monoglycerides,fatty acid, cholesterol, phospholipids are found on surface
how are free fatty acids and monoglycerides mostly absorbed
passive diffusion
short chain fatty acids/medium onces diffuse through enterocyte, and exit through basolateral membrane and enter villus capillaries. Whatt happens to long chain fattys
(also monoglycerides)
resynthesised to triglycerides in ER and incorporated to Chylomicrons
cholesterol is absorbed through
protein binding (NPC1L1) (neimann-pick-C1-like-1)
picks up several cholesterols, catherin coated pit allows endocytosis
ezetimibe is used in conjunction with statins in hypercholesterolaemia. what does it do
binds to NPC1L1 - prevents absorption
