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Ellie's MEH > Sesh 4- Lipid Transport > Flashcards

Sesh 4- Lipid Transport Flashcards

1
Q

What is the ideal level for plasma cholesterol?

A

<5mmol/L

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2
Q

What are phospholipids classified according to?

A

Their polar, hydrophilic head

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3
Q

Which enzyme converts cholesterol to cholesterol esters?

A

LCAT

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4
Q

What 3 things make up the cargo of a lipoprotein?

A
  1. Cholesterol esters
  2. TAG
  3. Fat soluble vitamins
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5
Q

What is the lowest density class of lipoprotein?

A

Chylomicron

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6
Q

What is the main lipoprotein class to transport dietary TAG?

A

Chylomicrons

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7
Q

What is the main lipoprotein class to transport TAG made by the liver?

A

VLDL

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8
Q

Which lipoprotein class has the largest diameter?

A

Chylomicrons

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9
Q

Why are chylomicrons only in the blood 4-6 hours after a meal?

A

Because they only transport dietary TAG.

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10
Q

What gives plasma a creamy appearance?

A

Presence of chylomicrons

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11
Q

Which integral apolipoprotein is found in IDL, LDL and VLDL?

A

ApoB

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12
Q

Which apolipoprotein is found in HDL?

A

ApoAI

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13
Q

Which apolipoprotein is added to chylomicrons before they enter the lymph?

A

Apo B-48

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14
Q

Which 2 apolipoproteins are added to chylomicrons once they are in the blood?

A

Apo C and E

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15
Q

Which enzyme can Apo C on chylomicrons bind?

A

Lipoprotein lipase

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16
Q

How are chylomicron remnants taken up by the liver?

A
  • LDL R on hepatocytes binds Apo E on chylomicrons

- Chylomicrons then taken up by receptor-mediated endocytosis for lysosomal degradation

17
Q

Which enzyme is responsible for taking up TAG into cells, thereby reducing the TG content of lipoproteins?

A

Lipoprotein lipase

18
Q

What do LDL’s have a high content of?

A

Cholesterol

19
Q

Why aren’t LDL particles efficiently cleared by the liver?

A

LDL R’s in liver have a high affinity for Apo E, but LDL doesn’t contain ApoE

20
Q

Why is LDL more susceptible to oxidative damage than other lipoproteins?

A

Is not efficiently cleared by liver, so has longer half life

21
Q

What is the function of LDL?

A

Provides cholesterol synthesised by the liver to peripheral tissues.

22
Q

How is the expression of cell surface LDL receptors controlled?

A

By cell cholesterol concentration

23
Q

Which lipoprotein is responsible for reverse cholesterol transport?

A

HDL

24
Q

How does HDL reduce the likelihood of atherosclerotic plaque formation?

A
  • Takes up excess cholesterol from endothelial cells lining blood vessels
  • Therefore reduces chance of foam cell formation etc
25
Q

Why does a cholesterol-free diet not necessarily reduce plasma cholesterol levels?

A

Body can still synthesise cholesterol

26
Q

How do statins reduce plasma cholesterol concentrations?

A

Inhibit HMG CoA reductase- 1st enzyme in cholesterol synthesis pathway

27
Q

Define a hyperlipoproteinaemia

A

Any condition in which after a 12 hour fast, plasma cholesterol and/or triglyceride is raised.

28
Q

Why will patients with a defect in LCAT have unstable lipoproteins with an abnormal structure?

A
  • No LCAT to convert surface lipid to core lipid

- Therefore cannot maintain the ratio of core to surface lipid which keeps lipoproteins spherical

29
Q

What is the function of HDL?

A

To transport cholesterol from cells which contain it excess to the liver or cells which require more cholesterol e.g. steroidogenic cells

30
Q

Name 3 signs that may be present in a patient with hypercholesterolaemia

A
  1. Corneal arcus
  2. Xanthelasma
  3. Tendon xanthomas
31
Q

What are class IIa hyperlipoproteinaemias a defect in?

A

The LDL receptor

32
Q

Give examples of 2 types of drugs used to treat hyperlipoproteinaemias

A
  1. Statins

2. Bile acid sequestrants

33
Q

In a fasted sample, what is the ideal level of plasma triglyceride?

A

< 2mmol/L

34
Q

Which class of lipoprotein contains the most cholesterol?

A

LDL

Ellie's MEH (12 decks)

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