CVS 5.2 - Pressures and Flow in the Systemic Circulation Flashcards Preview

ESA 2 > CVS 5.2 - Pressures and Flow in the Systemic Circulation > Flashcards

Flashcards in CVS 5.2 - Pressures and Flow in the Systemic Circulation Deck (22):
1

What is vasomotor tone?

The continuous contraction of the muscle (so there is always some vasocontstriction)

2

What agonises vasomotor tone?

Sympathetic stimulation of adrenergic alpha-1 receptors

3

What antagonises vasomotor tone?

Vasodilator factors

4

What is central venous pressure?

The pressure in the great veins supplying the heart

5

What is systolic pressure?

The maximum pressure reached in systole

6

What is diastolic pressure?

The minimum pressure reached in diastole

7

What is pulse pressure?

The difference between systolic and diastolic pressures

8

What is venous return?

The rate of blood back to the heart

9

What is vasoconstriction?

The decrease in flow due to contraction of arterial walls

10

What is vasodilation?

The increase in flow due to relaxation of smooth muscle in vessel walls

11

What is the significance of vasoconstriction/dilation?

Means that arterioles can vary flow = control

12

What is total peripheral resistance? What is it proportional to?

- The total resistance to blood flow from all of the systemic vasculature (not pulmonary)

- 1/need for blood

13

What affects systolic pressure?

- Force of contraction

- Total peripheral resistance (more difficult to pump blood so more pressure required)

- Compliance of arteries

14

What affects diastolic pressure?

- Systolic pressure

- Total peripheral resistance

15

What is the typical value of pulse pressure?

40 mmHg

16

What is average pressure?

Diastolic plus 1/3rd of pulse pressure

17

What causes the pulse wave? Where can it be felt?

- Contraction of the ventricles which propagates along the arteries faster than blood

- Where arteries are close to the skin e.g. anatomical snuffbox

18

What is the significance of arteries having distensible walls?

- Stretch during systole which allows more blood to flow in than out, doesn't increase pressure much

- Recoil during diastole which continues the flow

19

What is autoregulation?

When arterial pressure is within a specific range, most organs can take in the amount of blood flow they need

20

What is reactive hyperaemia?

- Restoration of blood flow after being stopped for a while. Leads to a large amount of blood entering after none at all

21

What are the effects of reactive hyperaemia?

- Continued respiration in tissues

- Vasodilators are still produced but aren't removed

- Maximum dilation of local arterioles = very high blood flow

22

Why can veins sometimes be used as arterial by-pass grafts?

- At higher pressures and volumes, their compliance becomes similar to that of arteries

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