LECTURE 25 Flashcards
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this is a precursor of bile salts, steroids, and vitamin D?
cholesterol
this organ is critical for the distribution of dietary and de novo cholesterol?
liver
what does cholesterol leave the liver as?
component of HDL, VLDL, free cholesterol in bile as bile salts/acids
in cholesterol synthesis where do all carbons come from and what cofactor supplies the electrons?
acetate
NADPH
where does cholesterol synthesis occur?
cytosol and ER
what is the rate limiting reaction in cholesterol synthesis?
HMG-CoA reducetase
what are the two anti cholesterol drugs that inhibit HMG-CoA reductase?
lovastatin and atorvastatin
T/F, cholesterol can be used for energy?
F
how is cholesterol removed from the body?
bile acids
free cholesterol
what do we do with cholesterol other than make bile salts and in membranes?
steroid hormones
cholesterol is the precursor of these 5 classes of steroid hormones, name them?
glucocorticoids (cortisol) mineralcorticoids (aldosterone) androgens (testosteron) estrogens (estrogen) progestins (progesterone)
how is cortisol transported in the blood after its bound to albumin? for sex hormones?
transcortin
sex hormone binding protein
what enzyme converts cholesterol to pregnenolone? this is rate limiting for all steroids
pregnenolone is then converted to what final products?
desmolase
aldosterone
cortisol
estradiol
fatty acids can be modified to become what type of signal? what is this signal called and name examples?
intercellular signals called eicosanoids
eicosanoids
PGs
thromboxanes
leukotrienes
this is the substrate for our bodies to make arachidonic acid?
linoleic acid
what is the source for PG synthesis?
arachidonate
this eicosanoids is used for smooth muscle contraction, bronchoconstriction, slow anaphylaxis, lysosomal release and WBC adhesion
leukotrienes
this eicosanoidsis made by platelets, promotes aggregation and vasoconstriction at wound sites?
thromboxane A2
this eicosanoids is what most tissues make it, especially kidney, causes vasodilation and is used to promote labor?
PGE2
this eicosanoid is in response to tissue damage?
leukotrienes
this eicosanoid is also made in most tissue, a vasoconstrictor which stimulates smooth muscle and uterine contractions?
PGF2
this eicosanoid is made by endothelial cells, causes vasodilation, and inhibits platelet aggregation?
PGI2
these are the two domains that comprise the prostaglandin synthase?
cyclooxygenase
peroxidase
what inhibits cyclooxygenase?
aspirin, saids, indomethacin, phenylbutazone
what inhibits thromboxane synthase?
dipyridamole
what is the energy yield per gram for the macromolecules?
fat
protein
carbs
alcohol
9 kcal/g fat
4 kcal/g protein
4 kcal/g carbs
7 kcal/g alcohol
why does glycerol go to the liver to broken down? what about the fatty acids?
there is no glycerol kinase in the adipocytes
diffuse through adipocytes to be bound to albumin, not used by brain, RBCs. adrenal medulla
fatty acid consumption used by what organs?
muscle and liver
a shortage of medium length fatty this enzyme is implicated in 10% of SIDs cases?
fatty acyl synthase
why is carnitine acyl transferase important in acyl CoA synthesis? what inhibits this?
it attaches the acyl group to carnitine to move from the cytosol to the mitochondrial matrix
malonyl CoA
so once in the matrix of the mitochondria, what process occurs to the acyl-CoA?
beta oxidation
what are the two enzymes used in energy harvesting from the beta oxidation of the fatty acid?
acyl-CoA dehydrogenase
L-3-hydroxylacyl CoA dehydrogenase
what is the net energy/palmitate? what about a TG with 3 palmitates, the glycerol attached?
what happens if the FA is unsaturated or odd# of carbons?
129 ATP
409 ATP, included in this is the glycerol which accounts for 22 ATP
isomerase and epimerase for unsaturated fatty acids which reduces the energy yield by 2 ATP/c=c because the acyl CoA DHase is skipped
Beta oxidation proceeds for odd chain length but the last cycle yields 1 AcCoA + 1 propionyl CoA rather than 2 AcCoA, what happens to the propionly CoA and AcCoA? it is converted to succinyl CoA
