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Flashcards in Control of blood flow Deck (20)
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1

What is active hyperaemia?

Increase in blood flow following increase in metabolic activity

2

As rate of metabolism increases, vasodilation takes place and there is an increase in blood flow. True or false?

True

3

Active hyperaemia is an example of intrinsic control. Why?

Because no hormones or nerves are involved in the response and the changes are a direct effect of the reduction in oxygen and increased carbon dioxide levels on the arterioles themselves

4

Active hyperaemia is in response to metabolic demand. When the rate of metabolite production has increased - vasodilation. True or false?

True

5

When does reactive hyperaemia take place?

When flow has been interrupted - restores flow

6

In reactive hyperaemia, vasodilation takes place in response to a _______ rate of metabolite removal

decreased

7

Active and reactive hyperaemia have the same mechanism. What is the difference?

The difference is in what they respond to
active - increased metabolite production
reactive - decreased rate of metabolite removal

8

What is the difference in the response of adrenaline binding to a1 receptors and B2 receptors?

Adrenaline binding to a1 receptors causes vasoconstriction
Adrenaline binding to B2 receptors causes vasodilation

9

How does angiotensin II control arteriolar resistance?

Formation of angiotensin II is a two step process.
Angiotensinogen is converted to angiotensin I by renin
Angiotensin I is converted to angiotensin II by ACE
One of the many effects of angiotensin II is to promote vasoconstriction, therefore increasing TPR and MAP

10

Which organ secretes renin?

Kidney

11

How does vasopressin/ADH control arteriolar resistance?

Promotes vasoconstriction

12

What is vasopressin secreted by?

Posterior pituitary gland

13

Adrenaline has the same affinity for all receptors. True or false?

False

14

In low concentrations, adrenaline binds to B2 receptors. True or false?

True - because it has a higher affinity for them and so promotes vasodilation

15

In high concentrations, adrenaline binds only to a1 receptors. True or false?

False - binds to a1 and B2 receptors, the effect it has on vascular resistance depends on which type of receptor predominates.
Because a1 receptors are on arteriole smooth muscle, high conc of adrenaline usually causes vasoconstriction
B2 receptors predominate in vascular smooth muscle of cardiac and skeletal muscle so high conc of adrenaline causes vasodilation here

16

Where are arterial baroreceptors found?

aortic arch and the carotid sinuses of the carotid arteries, in the neck

17

What do baroreceptors do when arterial pressure rises?

When arterial pressure rises, arterial walls stretch and stretch the sensory endings of the baroreceptors within them, inducing depolarisation
APs sent to CNS by baroreceptor axons

18

What happens to baroreceptors in hypertension?

Hypertension develops slowly over time. The accompanying rise in arterial pressure causes baroreceptors to lose their sensitivity, such that they become reset to a new higher pressure which becomes "normal".
In these conditions, baroreceptors continue to regulate arterial pressure but they keep it at higher level than normal.
Hypertension cannot be corrected by baroreceptors once this reset has taken place

19

CO can increase by 500% or more. True or false?

True

20

TPR is adjustable by 20% to 400%. True or false?

True