Anatomy and Physiology of the Cardio system

Question 1

What is the function of the cardiovascular system?

Answer 1

• Bulk flow system

- Transport: O2, CO2, nutrients, metabolites, hormones, heat -> thermoregulation

Question 2

How is flow related to pressure and resistance?

Answer 2

Flow = change in pressure/resistance

Question 3

What is change in pressure in relation to flow?

Answer 3

Pressure difference = mean arterial pressure - central venous pressure

Question 4

What is mean arterial pressure?

Answer 4

Measured as the flow that comes out of the left ventricle

Question 5

What is central venous pressure?

Answer 5

Measure just before the blood flows into the right ventricle

Question 6

What is resistance dictated by?

Answer 6

• Controlled by radius^4
• Selectively redirects flow
• Arterioles act as ‘taps’ controlling resistance to each vascular bed

Question 7

What is capacitance?

Answer 7

Related to the elasticity of vessels and how much blood can be stored within them

Question 8

What vascular beds are arrange in series in the body and why?

Answer 8

• The right side of the heart is in series with the left hand side as they have to pump approximately the same amount of blood
• The RHS of the heart is in series with the lungs as it needs to get all the deoxygenated blood
• The hypothalamus is in series with the anterior pituitary gland so it can directly send signals
• The gut is in series with the liver so it gets the nutrients first

Question 9

What vascular bed are parallel in the body and why?

Answer 9

- Left side of heart ->
Hypothalamus
Head
Legs
Arms
Gut
- Allows all tissues to get oxygenated
- Can send different proportions to get oxygenated

Question 10

Describe the cross-section of an elastic artery. Why is it like this?

Answer 10

• Wide lumen

- Elastic wall -> damp pressure variations

Question 11

What are examples of elastic arteries?

Answer 11

Aorta
Pulmonary trunk
Brachiocephalic trunk

Question 12

Describe the cross-section of a muscular artery. Why is it like this?

Answer 12

• Wide lumen
• Strong non-elastic wall
• Low resistance conduit
• Their job is to get blood from the aorta out to arterioles with minimum resistance

Question 13

Describe the cross-section of an arteriole. Why is it like this?

Answer 13

• Narrow lumen
• Thick contractile wall
• Control resistance and therefore flow
• Allow regional redirection of blood
• Resistance vessels

Question 14

Describe the cross-section of a capillary. Why is it like this?

Answer 14

• Narrow lumen
• Thin wall
• Exchange vessels

Question 15

Describe the cross-section of venules and veins. Why is it like this?

Answer 15

• Wide lumen
• Distensible wall
• Allow fractional distribution of blood between veins and rest of circulation -> esp heart
• Low resistance since there is low pressure
• Capacitance vessels

Question 16

What has more volume venules and veins or arteries?

Answer 16

Venules and veins

Question 17

What vessel has the highest pressure and what has the lowest pressure?

Answer 17

Highest: aorta
Lowest: venae cavae
Everything else in between is decreasing in pressure