Final Flashcards
(38 cards)
What 2 things cause the regulation of fa synthesis?
114
Acetyl-CoA Carboxylase.
Malonyl-CoA. (-)
What 3 things activate Acetyl-CoA Carboxylase?
114
Citrate: means that large amounds of OA and acetyl CoA are present and it’s a good time for fa synthesis. (Decrease of OA or acetyl-CoA will decrease fa synthesis).
Insulin: Secreted in response to a meal (pancakes)
Increased CHO, decreases fat
What inhibits Acetyl-CoA Carboxylase?
114
Palmitoyl-CoA: Feedback mechanism.
After fa synthesis, what happens to the fatty acids?
115
Triglycerides: adipocytes -> storage; Liver -> VLDLs; Small intestines -> Chylomicrons. Phosphoglyceride synthesis (nonpolar): Lipid bilayer of all cells.
Where does cholesterol metabolism take place?
119
Mostly in the liver (and small intestine).
As cholesterol intake increases, what happens to feedback regulation?
(119)
Feedback regulation decreases production.
What are the 3 main things cholesterol is turned into?
119
Progesterone (gluco-corticoids, mineralocorticoids, androgens, and estrogen). Vitamin D (UV light at the skin). Bile Acids (made in the liver).
Explain cholesterol biosynthesis:
120
Start with acetyl CoA –> HMG-CoA –> (HMG-CoA reductase) Mevalonate –> Active Isoprene… –> Cholesterol.
Overall: 18 acetyl-CoA’s, 6 Isoprene units, 18 ATP’s, 16 NADPH’s (from pentose shunt)
What is the key regulatory enzyme for cholesterol biosynthesis?
Is it long term or short term?
(121)
HMG-CoA reductase. Long term (hours, days). (Increased dietary cholesterol intake --> decreased HMG-CoA reductase levels, through enzyme degradation).
What regulates the short term cholesterol biosynthesis?
121
Phosphorylation: Inactive
De-phosphorylation: Active
What is the competitive inhibitor of HMG-CoA reductase?
121
Statins.
What are the 3 options for cholesterol turnover in the liver?
(122)
Excreted.
Converted to bile acids.
Turned into VDLD’s.
What are the 3 types of plasma/serum lipids?
123
Triglycerides.
Phospholipids.
Cholesterol (Cholesterol esters of f.a.)
(Lipids are pachaged with proteins to give a lipoprotein complex).
What are the reasons for transport of lipids?
123
Move to peripheral tissues (away from liver).
Transport of dietary lipids.
Excretion of cholesterol in bile.
Release of free fatty acids during mobilization.
What does VLDL represent?
How is it affected with CHO increase?
(125)
Represents transport of lipids from the liver to other tissues, especially adipose.
VLDL increases with CHO in the diet.
What does the deposit of tg in the tissues require?
125
LDLase.
What is most serum cholesterol associated with?
125
LDL’s
Where are HDL’s synthesized?
126
Liver.
Prevents excess cholesterol accumulation and is thought to remove excess cholesterol (requires LCAT enzyme).
What do chylomicrons do?
126
Carry dietary fats.
~1 hour for overall processing
Where are chylomicrons formed?
126
Within the mucosa cells.
They go through the lymphatics and enter the blood via the thoracic duct.
What does serum albumin do?
126
Carries free fatty acids (primarily those released from adipose in mobilization).
These aren’t directly measured as blood lipids (some ffa’s go to the liver and are packaged into VLDL and then go to the blood).
What binds bile acids and cholesterol?
127
Fiber.
What is the path for the transport of lipids from the liver?
(128)
Liver –> VLDL –> LDL –> Extrahepatic tissue LDL r/c
Familial Hypercholesterolemia involves decrease LDL r/c
What are the 2 hormones that act on own r/c’s?
129
Epinephrine.
Glucagon.
