Lipid Digestion Flashcards
Where does lipid digestion take place
Mouth (lingual lipase)
Stomach (lingual lipase and gastric lipase)
Small intestine (pancreatic lipase and bile salts)
Lipase activity: removal of fatty acid from locations ___ and ____ sequentially resulting in ___ and ___
1
3
two free fatty acids
one 2-monoacylglycerol (2-MAG)
lingal lipase
secreted by cells at the back of the tongue
Acid pH optimum (remains active in the stomach)
Slow activity (only active on the surface of teh lipid droplet)
Gastric Lipase
Secreted by gastric mucosa
Acid pH optimum
Activity limited to surface of lipid droplet
Pancreatic Lipase
Mixed with bile to form micelles
Secreted by the pancreas with procoplipase
_____ is required for lipase action
Procoplipase. Llipase alone is inhibited by bile salts
Procolipase is converted to colipase by trypsin
Cholesterol esterase
hydrolyze cholesterol esters to cholesterol and FFA
Phopsholipase A2 is activated by ____ and its activity requires ____
secreted as a zymogen and is activated by trypsin
activity requires bile salts
Phsospholipase A2 removes ____ from ___ position of phospholipids resulting in _____ and ____
One FA
From 2 position of phospholipids
Results in 1 FFA and 1 lysophospholipid
Bile contains
- Bile Salts
- Phospholipids
- Cholesterol
Bile malabsorption and also result in ____
malabsorption of fat soluble vitaments
Major cholesterol (sterol) transporter
Niemann-Pick C1-like protein
SCARB1 and CD36 have also been identified
ABC transporter
pump sterols that cannot be used back out of the cell (ABCG5 and 8)
where are bile salts absorbed (what is this termed)
Ileum
Enterohepatic circulation - returned to the liver by portal circulation
Transport of long chain fatty acids (>12C)
- Long chain fatty acids bind intestinal fatty acid binding protein( FAB) and are transprted to the ER
- Converted to triacylglycerols in the ER by acyl-CoA synthase
- Transported to blood in chylomicron
Transport of short and medium chain fatty acids
enter the hepatic portal vein as FFA and are transferred to the liver bound to albumin
major apoprotein added to chylomicrons
B-48
apoproteins are synthesized in the RER, Newly formed apoprotiens are assembled in the goli to form chylomicrons
chylomicrons are secreted to ____
lacteals (lymph) - travel up to the thoracic duct and then to the blood stream
Steatorrhea
excess fat in the stool
symptom of anything that interrupts lipid digestion and/or absorption
stools may be greasy and foul smelling
clay colored stools
result from lack of bile pigments
Orlisat
inhibitor of gastric and pancreatic lipases
reduced fat absorption by preventing triacylglycerol digestion
Side effect: steatorrhea
Olestra
resistant to action of lipases
Taste and consitency of fat but is nondigestible
Fat soluble vitamins may get passed through with olestra (** should be supplemented when taking)
Exetimibe
inhibits NPC1L1- diminished absorption by inhibiting cholesterol transport
