Short Term Control of Blood Pressure

Question 1

How is blood pressure controlled short term (3)

Answer 1

Arterial baroreflex
Other inputs
Lon term control

Question 2

When is it used (2)

Answer 2

Posture

Valsalva manoeuvre

Question 3

Mean arterial pressure =

Answer 3

Cardiac output X TPR

Question 4

What happens if the MAP is too low

Answer 4

Syncope

Question 5

What happens if the MAP is too high

Answer 5

Hypertension

Question 6

Other inputs to the medulary CV centres (4)

Answer 6

Cardiopulmonary baroreceptors
Central chemoreceptors
Chemoreceptors in muscle
Joint receptors

Question 7

What initiates the reflex

Answer 7

Stretch in receptors called baroreceptors

Question 8

Where are the pressure sensors primarily loctaed

Answer 8

Arterial walls of carotid artery sinus and aortic arch

Question 9

Where does the afferent nerves take the signal once a change is sensed

Answer 9

Medullary Cardiovascular Centres

Question 10

Features of long term regulation of blood pressure (5)

Answer 10

Cannot be by the arterial baroreceptors
Revolves around blood volume
Main sensors are cardiopulmonary baroreceptors
Effects tend to be hormonal
Act on blood vessels and kidneys

Question 11

Hormones involved in long term blood pressure regulation (3)

Answer 11

1. Renin-Angiotensin-Aldesterone system
2. Vasopression (ADH)
3. Atrial natriuretic peptide and brain natriuretic peptide

Question 12

Renin-Angiotensin-Aldesterone System (2)

Answer 12

Angiotensin II causes arteriolar constriction and increases TPR
Which increases BP
Aldesterone increases sodium reabsorption which increases plasma volume

Question 13

Vasopression (ADH)

Answer 13

Causes arteriolar constriction and increases TPR

Increases water permeability of collecting duct and increases plasma volume

Question 14

Atrial natriuretic peptide and brain natriuretic peptide

Answer 14

Causes arteriolar dilation and decreases TPR

Increase in sodum excretion and decreased in blood volume

Question 15

What is the effect of standing on blood flow (3)

Answer 15

Increased hydrostatic pressure
Reduced VR, EDV, SV, CO and MAP
Decreased baroreceptor firing rate

Question 16

What is the consequence if increased hydrostatic pressure

Answer 16

Pooling of blood in veins/venules of feet and legs

Question 17

What is the Valsalva manoeuvre

Answer 17

Forced expiration against a closed glottis

Question 18

What effect does the Valsalva manoeuvre have on the thoracic pressure

Answer 18

It increases it and this is transmitted through the aorta

Question 19

An increase in thoracic pressure means (5)

Answer 19

Decrease in venous return
Decrease in EDV
Decrease in SV
Decrease in CO
Decrease in MAP

Question 20

Phase 1 VM

Answer 20

Increase in intrathoracic pressure becomes positive due to compression of the thoracic organs
Impeded venous return
Decreases preload

Question 21

Phase 2 VM

Answer 21

Aortic pressure begins to fall due to reduced cardiac output as a result of reduced pre-load

Question 22

Phase 3 VM

Answer 22

Person starts to breath normally again and aortic pressure briefly decreases and HR increases reflexively

Question 23

Phase 4-5 VM

Answer 23

Increase in aortic pressure as the CO suddenly increases in response to a rapid increase in cardiac filling (damned blood build up)