L23 Flashcards

1
Q

What are the 3 components of the outside of a lipoprotein particle? What is in the core?

A

Apo-lipoproteins + free cholesterol + phospholipids = outer

Core = TGs + cholesterol esters

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2
Q

What surface molecule is unique LDL? HDL? (remember LDL & HDL are low/high density lipoproteins)

A

LDL, IDL, VLDL, remnants = apoB (binds LDL receptor)

HDL = apoA1

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3
Q

Equation for LDL

A

LDL = TC - (TG/5) - HDL

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4
Q

Does the liver secrete VLDL, IDL, or LDL?

A

VLDL

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5
Q

What happens to VLDL in circulation?

A

VLDL –> IDL
Releases TGs –> FFAs
- By lipoprotein lipase
FFAs can be taken into tissue for use and E source or into adipocytes for storage

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6
Q

What are IDL

A

Intermediate density lipoproteins = smaller, cholesterol enriched remnants

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7
Q

What happens to IDL in circulation

A
  1. Back to liver - donates cholesterol

2. IDL –> LDL, release more TGs –> FFAs into circulation

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8
Q

What is the fxn of LDL in the blood

A

Cholesterol transporter to either liver or other tissues

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9
Q

What happens if LDL is oxidized?

A

= athrogenic form

Can be taken up by marcophages without limit –> foam cell formation –> atherosclerosis

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10
Q

Describe LDL endocytosis

A

apoB + LDL receptor
In via clatharin coated pits
LDL into lysosome
Receptor recycled to membrane

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11
Q

Fxn of PCSK9 - SEs

A

LDL receptor degradation - no separation from LDL particle into lysosome
Net increase LDL in circulation b/c no receptors to bind to on tissues

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12
Q

Potential treatment for overactive PCSK9

A

mAb

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13
Q

Describe familial hypercholesterolemia - 4 most likely causes

A

High LDL –> premature CHD

  1. Hetero or homozygous for LDL receptor
  2. Mutated apoB so can’t bind LDL
  3. Mutated PCSK9 - excess
  4. LDL RAP1 mutations - can’t make clatharin pits for endocytosis
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14
Q

Physical exam findings for FH

A

Xanthomas

  • Achilles tendon
  • Corneal arcus = young pts
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15
Q

What is phytosterolemia?

A

Clinically present like FH, but doesn’t have to do with LDL

Increased absorption of non-cholesterol plant sterols

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16
Q

What is familial combined hyperlipidemia (2b)

A

Overproduce apoB - increased VLDL production

- Increased LDL & TGs

17
Q

What is type 3 hyperlipidemia? Labs + physical exam findings

A
"Remnant removal disease"
2 hits
- Homozygous for apoE - can't clear LDL correctly 
- Metabolic condition - T2D, etc
High cholesterol, TG, IDL
Yellow palm streaks + xanthomas
18
Q

Steps of TG digestion when eaten in food

A
  1. TG uptake - catabolized by gastric & pancreatic lipases
  2. FFAs –> chylomicrons in lymph –> venous circulation
  3. Chylomicrons anchors by GPIHBP1 - allows lipoprotein lipase to breakdown TGs –> FFAs
  4. FFAs stored in fat or muscle
19
Q

IF you have diabetes, why would you also have high TGs?

A

Increased adipocyte lipolysis
Excess VLDL secretion
VLDL –> LDL or HDL
Can undergo another TG reduction –> small, denser HDL & LDL

20
Q

What are the characteristics of smaller, denser HDL and LDL?

A
sdHDL = less efficient at cholesterol return to liver
sdLDL = more athrogenic
21
Q

Mechanism by which sdLDL is more arthrogenic

A

Less affinity for LDL receptor - more time in circulation
Easier entry into arterial wall
More susceptible to oxidative damage

22
Q

Normal blood TG levels

23
Q

Physical exam findings of high TGs

A

Xanthomas
Yellow palm streaks
Form layer in plasma overnight

24
Q

What lifestyle changes can significantly decrease TGs

A

Weight loss

Low fat diet - high in omega 3s

25
Fxn of HDL
Reverse transport Bring cholesterol from tissues (interstitial macrophages) to liver or to tissue that use cholesterol to make steroid hormones
26
LCAT fxn
Free cholesterol --> cholesterol esters in HDL formation
27
ABCA1 fxn
Free cholesterol uptake into new HDL
28
Tangier's disease
ABCA1 defect | Lipids build up in macrophages --> swollen reticuloendothelial organs (tonsils)
29
LCAT deficiency may result in...
Corneal opacification
30
Mechanism for high saturated fat diet causing high cholesterol
satFAs X LDL receptor Proinflammatory Prothrombotic
31
Which diet improves CHD survival rates?
``` Mediterranean diet Specifically, foods that lower LDL are: - Soluble fiber (oatmeal, cereals) - Antioxidants (artichokes) - Cherries - Chili peppers ```
32
``` Which of the following are TG rich vs cholesterol rich: Chylomicrons VLDL LDL HDL ```
Chylomicrons & VLDL = TG rich | LDL & HDL = cholesterol rich