L23 Flashcards Preview

P&T Block 1 > L23 > Flashcards

Flashcards in L23 Deck (32):
1

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

Apo-lipoproteins + free cholesterol + phospholipids = outer
Core = TGs + cholesterol esters

2

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

LDL, IDL, VLDL, remnants = apoB (binds LDL receptor)
HDL = apoA1

3

Equation for LDL

LDL = TC - (TG/5) - HDL

4

Does the liver secrete VLDL, IDL, or LDL?

VLDL

5

What happens to VLDL in circulation?

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

6

What are IDL

Intermediate density lipoproteins = smaller, cholesterol enriched remnants

7

What happens to IDL in circulation

1. Back to liver - donates cholesterol
2. IDL --> LDL, release more TGs --> FFAs into circulation

8

What is the fxn of LDL in the blood

Cholesterol transporter to either liver or other tissues

9

What happens if LDL is oxidized?

= athrogenic form
Can be taken up by marcophages without limit --> foam cell formation --> atherosclerosis

10

Describe LDL endocytosis

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

11

Fxn of PCSK9 - SEs

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

12

Potential treatment for overactive PCSK9

mAb

13

Describe familial hypercholesterolemia - 4 most likely causes

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

14

Physical exam findings for FH

Xanthomas
- Achilles tendon
- Corneal arcus = young pts

15

What is phytosterolemia?

Clinically present like FH, but doesn't have to do with LDL
Increased absorption of non-cholesterol plant sterols

16

What is familial combined hyperlipidemia (2b)

Overproduce apoB - increased VLDL production
- Increased LDL & TGs

17

What is type 3 hyperlipidemia? Labs + physical exam findings

"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

Steps of TG digestion when eaten in food

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

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

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

20

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

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

21

Mechanism by which sdLDL is more arthrogenic

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

22

Normal blood TG levels

23

Physical exam findings of high TGs

Xanthomas
Yellow palm streaks
Form layer in plasma overnight

24

What lifestyle changes can significantly decrease TGs

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