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Cardiology Week 3 > Lipid Biochemistry > Flashcards

Lipid Biochemistry Flashcards

1
Q

is cholesterol hydrophobic or philic?

A

hydrophobic

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2
Q

are the majority of cholesterols esterified or not?

A

majority is esterifies…70%

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3
Q

where do you find the esterified cholesterol in lipoproteins?

A

on the interior of the lipoprotein and the unesterified is on the outside

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4
Q

what organ is in charge of cholesterol synthesis and what percent does it make?

A

liver makes close to 80% of it

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5
Q

give the rate limiting enzyme in cholesterol synthesis

A

HMG CoA reductase

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6
Q

what hormone increases the action of HMG CoA reductase?

A

insulin

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7
Q

intermediates in the synthesis of cholesterol can lead to 3 types of important molecules…name them

A

ubiquinone
signal transduction molecules like Rho and Ras
complex glycoproteins

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8
Q

what is the name of the transcription factor that upregulates the production of HMG CoA reductase and the LDL receptor?

A

SREBP-2

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9
Q

what molecule is in charge of whether SREBP-2 is transcribed?

A

SCAP

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10
Q

what two things can inhibit SCAP?

A

intracellular cholesterol and LDL cholesterol

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11
Q

if you inhibit SCAP…what happens to HMG CoA reductase and LDL receptors?

A

production drops because you have less SREBP-2

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12
Q

what are the two ways to get cholesterol in a cell?

A

synthesis and uptake

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13
Q

what are the two ways to rid of cholesterol from a cell?

A

either secrete as bile salt or store it

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14
Q

if you have high cholesterol diet..what happens to the LDL receptors on the cells?

A

they begin to disappear because of the loss of SCAP action and ultimate loss of SREBP-2

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15
Q

what is the enzyme that helps store cholesterol?

A

ACAT

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16
Q

what can cause ACAT to decrease its activity?

A

saturated fats…ACAT uses PUFA to help store cholesterol by esterifying it…but with saturated fats it gets blocked

17
Q

what two ways does saturated fat lead to high cholesterol?

A

blocks LDL receptors from working

blocks ACAT from storing cholesterol

18
Q

what enzyme turns cholesterol into bile acids?

A

7a hydroxylase

19
Q

what molecule has to attach to bile acids for them to be secreted?

A

fiber

20
Q

what happens to bile acids on a low fiber diet?

A

the bile acids are not able to get secreted since no fiber and will travel back to the liver and be turned back into cholesterol via enterohepatic circulation

21
Q

name three roles of bile acids

A
  1. essential for fat digestion
  2. absorb fat vitamins
  3. eliminate cholesterol from body
22
Q

what percent of bile acids are reabsorbed? and the percent that is not…what is it representative of?

A

almost 99%…the slight percent that is not is the only way to rid of cholesterol from the body

23
Q

what is the role of lipoproteins?

A

to transfer triglycerides, phospholipids and cholesterol

24
Q

order the four lipoproteins in increasing density

A

chylomicrons
VLDL
LDL
HDL

25
Q

how is density of a lipoprotein related to size and triglyceride content?

A

inversely…larger the size lower the density

more triglyceride…lower the density

26
Q

how is density of a lipoprotein related to protein and phospholipid content?

A

directly…more protein means higher density

27
Q

what is the role of apoprotein C?

A

it activates lipoprotein lipase

28
Q

where is apoprotein C found?

A

mainly in peripheral tissues…like endothelial cells

29
Q

what is the role of lipoprotein lipase?

A

to break up the lipoproteins and take off triglycerides around the tissues that will be able to store the triglycerides

30
Q

where are apoproteins B and E found and what is their role?

A

they are found at the liver and help get LDL and IDL back into the liver

31
Q

what lipoprotein is made and released by the liver

A

VLDL

32
Q

what are the two sources of cholesterol/tricglycerides for the peripheral tissue?

A

chylomicrons from diet and VLDL from liver

33
Q

at the peripheral tissue, what happens to VLDL and what does the peripheral tissue release back to the liver?

A

its triglycerides get clipped by lipoprotein lipase..apo C denpendent

then releases LDL and IDL to go back to the liver

34
Q

what can nascent HDL do at peripheral tissue?

A

bind apoprotein A and pick up cholesterol…

35
Q

if HDL picks up cholesterol at peripheral tissue…what happens next?

A

LCAT esterifies the cholesterol in HDL

36
Q

what is the role of CETP in HDL molecules?

A

it can change cholesterol into VLDL, LDL or IDL or chylomicrons

37
Q

after HDL has picked up cholesterol from periphery and then let it get turned into LDL/IDL/VLDL/chylomicrons..what happens to the HDL and remnants of cholesterol?

A

they get internalized and destroyed at the liver

38
Q

what lipoprotine drives cholesterol from periphery to the liver?

A

HDL!!

39
Q

what molecule takes the longest to be picked up by periphery or liver?

A

LDL…hence why we measure LDL in blood

Cardiology Week 3 (15 decks)

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