Short Term Control of Blood Pressure

Question 1

What formula describes mean arteriolar pressure?

Answer 1

MAP = CO x TPR

Question 2

Why does mean arteriolar pressure (MAP) need to be regulated?

Answer 2

Too low leads to fainting (syncope)

Too high leads to hypertension

Question 3

What is the medical name for fainting?

Answer 3

Syncope

Question 4

What is syncope?

Answer 4

Fainting

Question 5

What is the baroreflex?

Answer 5

One of the bodies homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels

Question 6

What is the process of the baroreflex?

Answer 6

1) Aortic arch baroreceptors detect changes in blood pressure and send this information to the medullary cardiovascular centres by the vagus nerve, carotid baroreceptors detect changes and sent this information by the glossopharyngeal nerve
2) Responds by innervating the parasympathetic nerve (vagus) or sympathetic nerve depending on what response is required to return blood pressure to normal

Question 7

What do aortic arch baroreceptors send information to the medullary cardiovascular centre through?

Answer 7

Vagus nerve

Question 8

What do the carotid baroreceptors send information to the medullary cardiovascular centres through?

Answer 8

Glossopharyngeal nerve

Question 9

Where do the aortic arch and carotid baroreceptor sends information to?

Answer 9

Medullary cardiovascular centres

Question 10

What are other inputs to the medullary cardiovascular centres other than aortic arch and carotid baroreceptors?

Answer 10

Cardiopulmonary baroreceptors

Central chemoreceptors

Chemoreceptors in muscle

Joint receptors

Higher centres

Question 11

Can long term regulation of blood pressure be done by arterial baroreceptors?

Answer 11

No, revolves around blood volume

Question 12

How is long term control of blood pressure achieved?

Answer 12

Main sensors are cardiopulmonary baroreceptors

Effects tend to be hormonal

Act on blood vessels and kidneys

Question 13

Is long term control of blood pressure achieved neurally or hormonally?

Answer 13

Hormonally

Question 14

Is short term control of blood pressure achieved neurally or hormonally?

Answer 14

Neurally

Question 15

What do hormones act on to achieve long term control of blood pressure?

Answer 15

Blood vessels and kidneys

Question 16

What are examples of things that are used to achieve long term control of blood pressure?

Answer 16

Renin-angiotensis-aldosterone system

Vasopressin (antidiuretic hormone)

Atrial natriuretic peptide and brain natriuretic peptide

Question 17

How does the renin-angiotensin-aldosterone system regulate blood pressure in the long term?

Answer 17

Angiotensin II causes arteriolar construction and increases total peripheral resistance

Aldosterone increaes Na⁺ reabsorption and therefore increases plasma volume

Question 18

What effect does angiontensin II have?

Answer 18

Causes arteriolar constriction and increases total peripheral resistance

Question 19

What effect does aldosterone have?

Answer 19

Increases Na⁺ reabsorption and therefore increases plasma volume

Question 20

What is another name for vasopressin?

Answer 20

Antidiuretic hormone

Question 21

How does vasopressin (antidiuretic hormone) achieve long term regulation of blood pressure?

Answer 21

Causes arteriolar constriction and increases total peripheral resistance

Increases water permeability of collecting duct and therefore increases plasma volume

Question 22

How does atrial natriuretic peptide and brain natriuretic peptide achieve long term regulation of blood pressure?

Answer 22

Causes arteriolar dilation which decreases total peripheral resistance

Increases Na⁺ excretion and therefore decreases blood volume

Question 23

What is natriuresis?

Answer 23

Excretion of sodium in the urine

Question 24

What is excretion of Na⁺ in the urine called?

Answer 24

Natriuresis

Question 25

What are examples of when the baroreflex response would be used?

Answer 25

Due to posture

During the valva manoeuvre

Question 26

What is the effect of standing?

Answer 26

Increases hydrostatic pressure causing pooling of blood in veins/venules of feet and legs:

Decreases venous return, EDV, preload, stroke volume, cardiac output and mean arterial pressure
Decreases baroreceptor firing rate

Question 27

What is the baroreflex response to standing?

Answer 27

Decreases vegal tone

Increases sympathetic tone

Question 28

What is the impact of decreasing the vagus tone by the baroreflex whilst standing?

Answer 28

Increases heart rate and cardiac output

Question 29

What impact does the baroreflex increasing sympathetic tone when standing have?

Answer 29

Increase heart rate and cardiac output

Increases contractibility and increases stroke volume and cardiac output

Increases vasoconstriction which increases venous return, EDV, stroke volume and cardiac output

Increases arteriolar constriction which increases total peripheral resistance

Question 30

What effect does vasoconstriction have?

Answer 30

Increases venous return, EDV, stroke volume and cardiac output

Question 31

What does the tone of a nerve refer to?

Answer 31

Activity of the nerve

Question 33

What is the valva manoeuvre?

Answer 33

Forces expiration against a closed glottis

Question 34

What is the process of the baroreflex being used during the valva manoeuvre?

Answer 34

1) Increase in thoracic pressure is transmitted through the aorta
2) Increase in thoracic pressure causes decrease in venous return, EDV, SV, CO and MAP
3) Decrease in mean arterial pressure is detected by baroreceptors which initiates reflex which increases cardiac output and total peripheral resistance
4) Decrease in thoracic pressure is transmitted through to the aorta
5) Venous return is resorted, so is stroke volume but reflex effects are not worn of
6) Everything returns back to normal