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MEH > 5 Lipid transport > Flashcards

5 Lipid transport Flashcards

1
Q

How do we get cholesterol?

A

Some dietary
Mainly synthesised in the liver

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2
Q

Lipids are hydrophobic, what does this mean?

A
  • insoluble in water
  • problem for transporting in blood
  • transported in blood by carriers:
    -albumin - fatty acids
    -lipoprotein particles
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3
Q

Lipoprotein definition

A

Sphere of phospholipids used to transport lipid in bloodstream

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4
Q

Chylomicron function

A

Transports dietary TAGs from intestines to tissues

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5
Q

VLDL function

A

Transports liver synthesised TAGs to adipose tissue for storage

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6
Q

IDL function

A

Transports liver synthesised cholesterol from liver to tissues

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7
Q

LDL function

A

Transport of liver synthesised cholesterol to tissues

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8
Q

HDL function

A

Transports excess cholesterol from peripheral tissues to liver for disposal as bile salts

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9
Q

Density of lipoproteins order

A

Least
Chylomicron
VLDL
IDL
LDL
HDL
Most

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10
Q

Size of lipoprotein order

A

Biggest
Chylomicron
VLDL
IDL
LDL
HDL
Smallest

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11
Q

When are Chylomicrons present in blood?

A

4-6 hours after eating

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12
Q

What do chylomicrons look like after flotation ultracentrifugation?

A

Creamy appearance

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13
Q

How is density of lipoproteins measured?

A

Flotation ultracentrifugation

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14
Q

Apolipoprotein definition

A

Peripheral and integral proteins on lipoproteins
Peripheral - on top
Integral - pass through

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15
Q

Apolipoprotein function

A
  • structural: packaging water insoluble lipids
  • functional: cofactor, ligands for cell surface receptor
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16
Q

Lipoprotein lipase function

A

Hydrolyses TAGs in lipoprotein
Needs ApoC-II as cofactor

17
Q

What is the cofactor of lipoprotein lipase?

A

ApoC-II

18
Q

When does a Chylomicron become a Chylomicron remnant?

A

When lipid content drops below 20%

19
Q

Relationship between VLDL,IDL and LDL

A

VLDL > IDL > LDL
IDL - 30% depletion
LDL - 10% depletion

20
Q

What is bad cholesterol?
Why?

A

LDL
- Longer half life: more susceptible to oxidative damage
- no apoC/E: no efficiently cleared by liver

21
Q

What happens to oxidised LDLs?

A

Taken up by macrophages
Foam cells form
Can cause atherosclerosis

22
Q

How do LDLs enter tissues?

A

Receptor mediated endocytosis

23
Q

What happens in receptor mediated endocytosis?

A

Receptors for ApoB-100 ligand on LDL allow LDL to be endocytosed
LDL digested by lysosomes

24
Q

What is good cholesterol?
Why?

A

HDL
- Removes excess cholesterol from peripheral tissues
- Takes to liver or steroidogenic cells to be removed
- Reduced chance of foam cells and forming atherosclerotic plaques

25
Q

Hyperlipoproteinaemia defintion

A

High levels of 1 or more classes or lipoprotein

26
Q

Causes of hyperlipoproteinanemia

A

Overproduction
Under removal

27
Q

What is type I hyperlipoproteinaemia?

A

Chylomicron present in plasma even when fasting
Due to defective LPL

28
Q

What is type IIa hyperlipoproteinaemia?

A
  • High levels of oLDL > foam cells > risk of atherosclerosis
  • Due to defective LDL receptor so LDL gets oxidised
    familial hypercholesteroaemia
29
Q

What is type III hyperlipoproteinaemia?

A

Raised IDL and Chylomicron remnants
Due to defective apoE

30
Q

What is the first treatment of hyperlipoproteinaemia?

A
  • DIET : reduced saturated fats and lipids, increase fibre
  • LIFESTYLE : exercise, stop smoking - reduces cardiovascular risk
31
Q

Second treatment of hyperlipoproteinaemia

A
  • STATINS : inhibits HMG-CoA reductase, used in cholesterol synthesis so less cholesterol made
  • BILE SALT SEQUESTRANTS - bind bile salts in GI tract so liver produces more bile acids (uses cholesterol)
32
Q

What is hypercholesteroaemia?

A

High levels of cholesterol in blood

33
Q

What is the normal cholesterol level in blood?

A

<5mmol/L

34
Q

Signs of hypercholesteroaemia

A
  • XANTHELASMA : yellow patches on eyelids
  • TENDON XANTHEMA : nodules on tendons
  • CORNEAL ARCUS : white/blue circle around eye
35
Q

What is xanthelasma and what it is a sign of?

A

Yellow patches on eyelids
Hypercholesteroaemia - high levels of cholesterol

36
Q

What is tendon xanthema and what is it a sign of?

A

Nodules on tendon
Hypercholesteroaemia- high levels of cholesterol

37
Q

What is corneal arcus and what is it a sign of?
Difference in young and older people

A

White/blue circle around eye
Hypercholesteroaemia- high levels of cholesterol
Normal in older people
Concerning in younger people

38
Q

Process of plaque formation

A

1) LDL have longer half life so get oxidised
2) oLDL engulfed by macrophages
3) foam cells made + accumulate in intima of blood vessels
4) fatty streak formed
5) evolves into atherosclerotic plaque > angina
6) plaque ruptures
7) thrombosis (clotting) > stoke or myocardial infarction

39
Q

What can a ruptured plaque cause?

A

Stroke
Myocardial infarction

MEH (23 decks)

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