Lecture - CVS (Rajesh Physiol 9 Special Circulation)

Question 1

Coronary circualtion

1. What’s the coronary blood flow like in a resting human and during heavy exercise?
2. What’re the 5 names of arteries on the heart that you need to know?
3. 95% of the coronary venous blood returns to the ____ ____. Where does the rest drain into?
4. Where do the thebesian veins drain? What does this mean for the oxygenation?
5. What’re the two special tasks the coronary circulation needs to do?

Answer 1

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Question 2

Special structural features

1. What are the capillaries like in skeletal vs cardiac muscle?
2. What does this high capillary density confer? (2 things)
3. What’s the O2 extraction of the myocardium? But doesn’t it already have a high flow?
4. Go understand the graph on slide 12 and explain the graph to a wall (yes, a wall because no one else wants to listen to you 😂)
5. So how do deal with exercise?

Answer 2

3. Yeah but it still needs to extract 65-75% of the oxygen to meet its demands as well as the high flow
4. Through increasing BF by metabolic hyperaemia

Question 3

Metabolic hyperaemia

1. This is the most dominant form of ____ _____ in myocardium
2. So you increase coronary blood flow in proportional to what? (As in skeletal muscle)
3. What’s the flow chart for this active hyperaemia?
4. So in metabolic hyperemia, the blood flow is linked to demand for oxygen. What does the grpah with coronary blood flow vs oxygen consumption look like?
5. What’re two major vasoilators of coronary resistance vessels and when are they produced and how do they work?

Question 4

Ischemic vasodilation (reactive hyperemia) limit damage by coronary artery disease

1. In angina pateints, what does hypoxic vasodilation occur as a result of?
2. In addition to dilating the vessels, what does this reactive hyperemia/ischemic vasodilation/hypoxic vasodilation help during a heart attack?
3. So what is the difference between metabolic hyperemia (active hyperemia) and hypoxic/ischaemic vasoilation (reactive hyperemia) - slide 16

Answer 4

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Question 5

What’s your explanation for why coronary stenosis usually causes angina only during exercise/stress?

Include these terms in the explanation:

• Ohm’s law
• normal coronary artery resistance
• metabolic vasodilation
• stenosis, arterial resistance
• arteriogenesis
• reactive hyperemia
• exercise
• O2 demand
• angina

Have a look at the graph on slide 19

Answer 5

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Question 6

Special problems of coronary circulation

1. There are functional end-arteries
   - what does this mean? (there are two types of end arteries…)
   - when atheroma (what is this?) develops, what happens? (2 things)
2. _____ obstructs coronary blood flow
   - when it says 2/3rd of coronary arterial system is intramural - what does that mean?
   - so systole compresses the vessels during what phase of the cardiac cycle?
   - 80% of myocardial blood flow occurs during when?
   - Beta blockers in heart failure or after MI increase what and hence get what?

Answer 6

2. So the vessels are in the walls so systole will compress them

Question 7

Assessment of coronary flow

What are the two?

1. What is coronary angiography (arteriography) and what does it show the location of?
2. What does isotope imaging of ventricle wall (gamma scan) show?

Question 8

Special tasks of skin/cutaneous circulation

-What are the two special tasks and what are the mechanisms by which this is done?

Answer 8

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Question 9

Special structures of cutaneous circulation

1. What is the purpose of arterio-venous anastomoses in extremities
2. Is cutaneous blood flow affected by one of or both of outside and core temperature?
3. What happens to the skin vessels when you increase ambient temperature……what about when there is a drop in ambient temperature?
4. What is the paradoxical cold vasodilation? Why does it happen? What two reasons is it due to?
5. So there is increased skin blood flow in response to increased core temperature (like exercise and fever), but what 2 things is this vasodilation and sweating cuased by?
6. What is the disease called where you have excessive vasoconstrictor response to cold - how does it manifest?
7. What can prolonged obstruction of flow by external compression cause? What’re some examples?
8. What does postural fainting have to do with hot weather?

Answer 9

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Question 10

Cerebral circulation

1. What’re the 2 special tasks
2. Grey matter has a high rate of oxidative metabolism - what does this mean?
3. When do you lose consciousness after cerebral ischaemia? When would it result in excessive damage?
4. What is the circle of Willis and what is its purpose? Name the arteries involved
5. How does the brain acheive a high O2 delivery to neurons?
6. Does the grey matter have a high basal flow or a low basal flow?
7. Go read the graphs on slide 46
8. Why is the brain a selfish organ?
9. What maintains perfusion during hypotension?
10. Is cerebral blood flow constrant throughout life?
11. What’re some problems with cerebral circulation?
12. Go read summary table xx

Answer 10

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