Regulating Blood Flow Flashcards Preview

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Flashcards in Regulating Blood Flow Deck (24)
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1
Q

What is blood flow affected by

A

MAP Blood pressure (CO x TPR)

2
Q

Where does the largest drop in pressure occur

A

Arterioles

3
Q

What is arterioles role in terms of blood flow

A

Match blood flow (determined by pressure) with metabolic need of cells

4
Q

What is the partial contraction of smooth muscle in vessels called

A

Tissue vessel tone

5
Q

What is it called when tissue vessel tone reduces diameter

A

Vasoconstriction

6
Q

When would vasoconstriction of the vessel tone occur

A

If some cells have higher metabolic need eg in exercise

7
Q

What is vasodilation

A

When tissue vessel tones increase in radius and decrease TPR therefore BP decrease (BF increases)

8
Q

What are the other way of saying arterioles

A

Sphincter

9
Q

What are the 3 mechanisms which control the vessel tone and therefore affect BF

A

Local control

Hormone control

Neural control

10
Q

What is auto regulation (local control) of vessel tone

A

Works on the fact if you increase pressure this will increase blood flow (P/ r)

11
Q

What happens when there is increased pressure which increases BF
(In auto regulation)

A

Pressure will stretch muscles and this promotes Ca2 influx

This causes muscle contraction which therefore regulates blood flow by increasing resistance = lowered blood flow (P/R)

12
Q

Metabolic control is also local, which metabolites cause vasodilation (increasing BF by decreasing resistance)

A

Co2, H+, K+ , temp, adenosine

13
Q

Which metabolite causes vasoconstriction to increase resistance and decrease BF

A

Oxygen

Cells don’t need supply of blood flow as much

14
Q

What are the 4 hormonal vasodilators which increase BF by reducing resistance

A

Histamine
NO
Kinins
Adrenaline

15
Q

Which receptor does adrenaline need to bind to to be a vasodilator

A

B2

16
Q

What does NO bind to which then produces cGMP for vasodilation

A

Guanylyl cyclase

17
Q

What are the 3 vasoconstrictor hormones

A

Adrenaline (bound to A1)

ADH

Angiotensin II

18
Q

What are the 3 neural controls of vessel tone / BF

A

Sympathetic vasoconstrictor fibres

Sympathetic vasodilation fibres

Parasympathetic vasodilation fibres

19
Q

How do sympathetic vasoconstrictors work

A

They release adr/nadr

When bound to A1 this causes vasoconstriction

(Unlike in heart when they bind to B1)

20
Q

What happens when there’s a lower frequency of sympathetic vasoconstrictor signals

A

Vasodilation due to less nadr binding at A1

21
Q

What do sympathetic vasodilators release and the effect of it

A

Ach

This causes increased Ca2+ (via ip3)

This causes NO synthesis and therefore vasodilation

22
Q

Do parasympathetic vasodilators work the same as sympathetic vasodilators

A

Yes

23
Q

CO affects pressure which if increased will also increase BF, what happens to CO when exercising

A

Increased CO from heart which causes vasodilation of the vessels to skeletal muscle to increase BF for supplying o2

24
Q

Why doesn’t BP increase during exercise despite CO increasing

A

Because TPR will decrease as vasodilation in vessels occurs to allow BF