Lipid Digestion Concept Map Biochem 1 Exam 3

Where does lipid digestion start?

In the mouth

What is lingual acid?

lipid digestive agent of the mouth

What can lingual acid do?

Digests the SN-3 fatty acid on triglycerides up to Laurate (Lauric acid)

Does lingual lipase have the ability to digest the SN-1 or SN-2 fatty acid?

no

Does lingual lipase have the ability to digest phospholipid or cholesterol?

no, only triglycerides (SN-3 to be exact)

Does the stomach have the ability to digest phospholipids or cholesterol?

no

What occurs within the stomach?

emulsification due to peristalsis and phospholipids

What is the function of gastric lipase?

Digests the SN-3 fatty acid on triglycerides up to Laurate (Lauric acid)

Where does phospholipid and cholesterol digestion occur?

only in the small intestine

Are brush border lipases within the small intestine?

no

What is entering the the small intestine and where from? (REFRESHER)

bile from the gallbladder, enzymes from the pancreas

Are brush border or pancreatic enzymes in the small intestine the reason for lipid digestion?

pancreatic enzymes, because there are no brush border lipases in the small intestine.

What activates procolipase to colipase?

trypsin

What are the three things that you need in order for pancreatic lipase to become active?

colipase, bile, Ca2+ (cofactor calcium)

Once pancreatic lipase is activated what does it do?

digests triglycerides by removing SN-1 and SN-2 fatty acids regardless of chain length

What are the products of triglyceride digestion in the small intestine?

Free fatty acids (SN-1 and SN-3) and monoglycerides (glycerol backbone with SN-2)

What is the activated form of prophospholipase A2?

phospholipase A2

What are the three lipases released from the pancreas?

Active pancreatic lipase, phospholipase A2, esterase

What is the function of phospholipase A2?

Digests phospholipids by removing the SN-2

What is the function of esterase?

Digests cholesterol and vitamins A & E (storage form)

What is the product of esterase digestion?

Free fatty acids of Vitamin A & E

What are the products of phospholipase A2 digestion?

Lysophospholipids and fatty acids

What are lysophospholipids?

digested phospholipids (fatty acid removed)

All products of pancreatic lipase digestion coalesce into lipid droplets called....

micelles

How are micelles absorbed?

passive diffusion

Where are our lipids reesterified (remade)?

Smooth endoplasmic reticulum (SER)

How are lipids transported?

specialized transporters called lipoproteins

Where are chylomicrons made?

small intestine

What do chylomicrons carry mostly?

exogenous triglycerides from our diet

What is the job of chylomicrons?

deliver triglycerides to muscle and adipose tissues through activation of lipoprotein lipase

What activates lipoprotein lipase?

Apo CII on chylomicrons

What does lipoprotein lipase do?

breaks down triglycerides in chylomicrons into glycerol + FA (essential for getting triglycerides into cells)

Where is VLDL made?

liver

What does VLDL mostly carry?

triglycerides from exogenous and endogenous sources (diet, and what is made in liver itself)

What is the job of VLDL?

deliver triglyercerides to adipose tissue through activation of lipoprotein lipase

Does VLDL contain Apo CII?

yes, activates lipoprotein lipase to breakdown triglycerides

Once glycerols and FA are inserted into muscles and adipose what happens to them?

they reform triglycerides and are stored in those cells as such

What does LDL stand for?

Low Density Lipoprotein

What is LDL made from?

VLDL

What does LDL mostly carry?

cholesterol

What is the job of LDL?

deliver cholesterol to cells

How does LDL enter cells to deliver cholesterol?

binds to LDL receptor, and both the LDL cholesterol and receptor are engulfed by the cell. (receptor mediated endocytosis)

What is the receptor ligand that allows for receptor mediated endocytosis of LDL to occur?

Apo-B100

What part of the cell digests the LDL once it is engulfed?

lysosome

What are things that can increase the amount of LDL that we have?

Trans fats and excessive amounts of saturated fats

What are the lipoproteins that transport lipids?

chylomicron, VLDL, LDL, HDL

What does HDL mostly carry?

protein

Where is HDL made?

liver, little in small intestine

What is the job of HDL?

reverse cholesterol transport

What does reverse cholesterol transport mean?

picking up free cholesterol using LCAT, and take it back to the liver telling HMG CoA reductase to slow down on making cholesterol.

What is LCAT

Lecithin-Cholesterol- Acyltransferase

What does LCAT do?

Makes cholesterol esters out of FREE cholesterols. (cannot pick up esters, only free cholesterols)

What in our diets decreases the amount of HDL that we have?

Trans fats >:(