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Biochemistry > Cholesterol metabolism and health and disease > Flashcards

Cholesterol metabolism and health and disease Flashcards

1
Q

what pathway are cholesterol and fatty acids absorbed

A

exogenous pathway

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2
Q

what happens to cholesterol and fatty acids in the exogenous pathway

A

Triglycerides are formed in the intestinal cells from free fatty acids and glycerol
Cholesterol is esterified

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3
Q

what do Triglycerides and cholesterol combine to form

A

chylomicrons

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4
Q

Once Chylomicrons enter the circulation where do they travel

A

travel to peripheral sites

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5
Q

In peripheral tissues, free fatty acids are released from the chylomicrons to be used as what

A

energy, converted to triglyceride or stored in adipose

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6
Q

In peripheral tissues, free fatty acids are released from the chylomicrons to be used as what

A

energy, converted to triglyceride or stored in adipose

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7
Q

what is the main site of LPL activity

A

adipose & mammary tissue, skeletal muscle, myocardium.

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8
Q

what do Endocytosed chylomicrons that are catabolized
by lysosomes do

A

release cholesterol for excretion as bile acids in bile
or incorporated into VLDL

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9
Q

what do Endocytosed chylomicrons that are catabolized
by lysosomes do

A

release cholesterol for
excretion as bile acids in bile
or incorporated into VLDL

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10
Q

what happens in the endogenous pathway

A

VLDL FORMS IDL or VLDL remnants.

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11
Q

What do LDL particles contain

A

a core of cholesterol esters and a smaller amount of triglyceride.

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12
Q

What is LDL is internalized by

A

hepatic and non-hepatic tissues.

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13
Q

In the liver, what is LDL converted into

A

bile acids and secreted into the intestines.

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14
Q

In non hepatic tissues, what is LDL used in

A

hormone production, cell membrane synthesis, or stored.

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15
Q

LDL is also taken up by macrophages and other cells which can lead to what

A

excess accumulation and the formation of foam cells which are important in plaque formation.

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16
Q

What is HDL

A

HDL is a heterogenous group of macromolecules with different physical properties and chemical components

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17
Q

What are the 2 subclasses of HDL

A

HDL2 and HDL3

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18
Q

What is the function of HDL

A

to reverse transport of cholesterol from different tissues to the liver for excretion

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19
Q

What is the function of HDL

A

to reverse transport of cholesterol from different tissues to the liver for excretion

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20
Q

What does Reverse cholesterol transport begins with

A

the removal of cholesterol from arterial foam cells

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21
Q

what happens to Cholesterol from non-hepatic peripheral tissues

A

is transferred to HDL by the ABCA1(ATP-binding cassette transporter).

22
Q

what does ApoA-1 act as

A

an acceptor and the phospholipid component of HDL acts as a reservoir for the cholesterol.

23
Q

what enzyme coverts cholesterol to cholesterol esters

A

The cholesterol is converted to cholesteryl estersby the enzyme LCAT (lecithin-cholesterol acyltransferase).

24
Q

what does LCAT do

A

Cholesterol → cholesteryl esters catalysed by lecithin cholesterol acyltransferase (LCAT) in peripheral tissues

25
Q

Where is ACAT2 found

A

found in both intestine and liver

26
Q

Where is ACAT1 found

A

in all tissues

27
Q

what is cholesterol

A

Most abundant steroid

It is amphipathic

Can be found in large concentrations in the brain, spinal cord, and liver

Liver is the most important site of cholesterol biosynthesis, although other sites include the adrenal glands and reproductive organs

28
Q

what is the function of cholesterol

A

Serves as the major precursor for the synthesis
vitamin D3
steroid hormones (cortisol, cortisone, and aldosterone in the adrenal glands)
sex hormones (progesterone, estrogen, and testosterone).

29
Q

what is CVD

A

CVD includes all the diseases of the heart & circulation including coronary heart disease, angina, heart attack, congenital heart disease and stroke

CVD is responsible for a ¼ of all deaths in the UK

About half of all deaths from CVD are from CHD and about a quarter are from stroke

CHD by itself is the most common form of heart disease, and the most common cause of death for both men and woman globally

The cost of CVD to the UK healthcare system in 2020 was £22.5 billion

30
Q

what arteries relate to CHD

A

Disease involving the network of blood vessels (coronary arteries) surrounding and serving the heart

31
Q

What plaques effect the coronary arteries

A

the accumulation of atherosclerotic plaques in coronary arteries that lead to a reduction in blood flow to the myocardium.

32
Q

what does CHD lead to

A

myocardial infarction (MI) and sudden death

33
Q

what is Atherosclerosis

A

Risk factors: unhealthy blood Chol; high BP; smoking etc
Thickening of the arterial wall; artery becomes occluded (blocked)
Begins in childhood with clinical symptoms in middle age or later
Leads to ischaemia (lack of nutrients and oxygen) to cells supplied by the artery

34
Q

how do you lower blood cholesterol

A

Regular exercise
Reducing Chol & Sat fat
Drugs - HMG-CoA reductase inhibitors - statins -lovastatin (Mevacor) & atorvastatin (Lipitor)

35
Q

what is a major cause of CHD

A

atherosclerosis

36
Q

What are the 3 stages of plaque formation

A
  1. fatty streak
  2. plaque progression
  3. plaque disruption-unstable plaques will rupture leading to thrombus and possible thrombosis
37
Q

what is angina

A

A narrowing of one or more coronary arteries, restricting the flow of blood to the heart

Pain occurs during physical activity and sometimes at rest

Crushing pain which may move to left arm or to the jaw

38
Q

how is stroke manifested

A

cerebral arteries

39
Q

how is myocardial infarction manifested

A

coronary arteries

40
Q

how is leg pain, DVT, gangrene manifested

A

peripheral arteries

41
Q

what is heart attack

A
  1. Acute Myocardial Infarction
  2. death, long term complications
  3. happens when one or more of the coronary arteries supplying blood to the heart muscle becomes suddenly blocked and Shortage of blood supply to heart muscle leads to tissue death
42
Q

what is Arrhythmia

A
  1. Disturbance in heart rhythm leading to ineffective pumping
  2. Common cause of death in early stage heart attack
  3. Bradycardia describes a rate of less than 60 beats per minute
  4. Tachycardia usually refers to a heart rate of more than 100 beats per minute
43
Q

what tool diagnoses arrhythmias

A

An electrocardiogram

44
Q

what treats issues with the heart

A

pacemaker

45
Q

what is heart failure

A

when the pumping mechanism is ineffective and can be sudden or over a long time

46
Q

what are the symptoms of heart failure

A

Chest discomfort
Shortness of breath
Nausea
Light headed

47
Q

what is cardiac arrest

A
  1. Heart stops pumping
  2. Ventricular fibrillation most common cause and can be related to CHD, cardiomyopathy, electrocution, lack of oxygen, drug misuse
  3. CPR and defibrillation used to treat
48
Q

what is a stroke

A

disturbance to brain function caused by inadequate blood supply (cerebral infarction) or by direct damage by bleeding into the brain (cerebral haemorrhage)

49
Q

what is vascular dementia

A
  1. Narrowing of small blood vessels in the brain
  2. Mini strokes – transient ischaemic attacks (TIA)
    Degenerative condition causing confusion, memory loss, difficulty with speech and balance and personality change
  3. > 65 years most common
50
Q

what are common medications for cholesterol issues

A

Probucal: increases conversion of cholesterol to bile acids

Cholestyramine: sequesters bile acids for excretion. As the body loses bile acids, it replaces them by converting blood cholesterol to bile acids

51
Q

what are statins

A

A class of drugs used to lower cholesterol levels

Inhibit the enzyme HMG-CoA reductase, which plays a role in the production of cholesterol in the liver

52
Q

what diet should you follow to reduce CVD

A

Replace SFA with unsaturated fats,

Avoid trans fats

Eat 2 portions of fish per week

Increase fibre intake

Biochemistry (20 decks)

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