Cardiovascular regulation

Question 1

What do increased activity of baroreceptors cause?

Answer 1

Heart and blood vessels reduce cardiac output

Question 2

What factors cause increased systemic vascular resistance?

Answer 2

Increased RBC’s, increased blood viscosity, total blood vessel length, decreased blood vessel radius and increased systemic resistance, cause increased mean arterial blood pressure

Question 3

What is the primary objective of cardiovascular regulation?

Answer 3

To maintain a stable MAP, to ensure adequate blood flow to vital organs

Question 4

Where do you find non-encapsulated nerve endings?

Answer 4

Carotid sinus and aortic arch

Question 5

What are mechanoreceptors sensitive to?

Answer 5

Stretch

Question 6

What does increased arterial pressure do to baroreceptors?

Answer 6

Increases distending pressure on arterial wall to stretch which excites baroreceptors

Question 7

Where do baroreceptor afferents project?

Answer 7

Glossopharyngeal and vagus nerves

Question 8

What do increases in afferent input lead to?

Answer 8

Increased parasympathetic and decreased sympathetic stimulation of the heart

Question 9

If baroreceptors detect a decrease in blood pressure what happens?

Answer 9

Increased sympathetic stimulation, increased secretion of epinephrine and noradrenaline, increased heart stroke volume and CO.
Vasoconstriction causes increased systemic vascular resistance

Question 10

What is orthostasis?

Answer 10

Effect of gravity on the distribution of venous blood, more venous volume, reduction in pressure, EDV, pulse pressure and MAP

Question 11

How does CV centre respond to orthostasis?

Answer 11

Less vagal outflow to the heart more outflow in cardiac and vasomotor nerves, increased heart rate and contractility, increase TPR and MAP

Question 12

What are arterial baroreceptors responsible for?

Answer 12

Buffering of blood pressure

Question 13

What has the responsibility of regulating blood pressure long term?

Answer 13

Cardiopulmonary pressure receptors and hormonal influences

Question 14

What receptors respond to much lower pressures than baroreceptors?

Answer 14

Atria and pulmonary arteries

Question 15

What is the primary role of cardiopulmonary stretch receptors?

Answer 15

Regulate blood volume, primary determinant of cardiac output so determines arterial pressure

Question 16

If venous blood pressure decreases what is this reflected by?

Answer 16

Less atrial pressure and less stimulation of cardiopulmonary stretch receptors causing:
Increase of ADH from hypothalamus, increasing reabsorption of fluid from renal tubules and production of concentrated urine
Reflex that constricts the afferent renal arterioles reducing the rate of glomerular filtration
- reduces fluid loss in urine and increases blood volume

Question 17

What other effect does ADH have?

Answer 17

Vasoconstrictor, in the gut and spleen, increases TPR so the fall in atrial pressure triggers compensatory responses to restore mean arterial pressure

Question 18

When both baroreceptors and cardiopulmonary stretch receptors are denervated what happens?

Answer 18

Leads to marked increase in mean arterial pressure

Question 19

What do chemoreceptors do?

Answer 19

Monitor chemical composition of arterial blood sensitive to oxygen, hydrogen ions

Question 20

How do chemoreceptors affect breathing

Answer 20

Increased rate and depth of breathing, increase in tidal volume - lung inflation reflex - small vasodilation.
Increase in cardiac output and TPR producing increase in mean arterial pressure

Question 21

What is the most important determinant of arterial pressure in long term?

Answer 21

Blood volume

Question 22

The greater the renal arterial perfusion pressure the greater the rate of…?

Answer 22

Glomerular filtration and urine production

Question 23

The relationship between renal arterial perfusion pressure and glomerular filtration is amplified by?

Answer 23

Renin-angiotensin-aldosterone system

Question 24

What is a fall in blood volume or renal blood flow detected by?

Answer 24

Juxtaglomerular cells in the kidney which release enzyme renin

Question 25

What chain of events does renin trigger?

Answer 25

Angiotensinogen released by liver, angiotensin 1 and 2 released and aldosterone, more sodium retention in renal tubular cells which increases blood volume

Question 26

What are the end results of the renin-angiotensin-aldosterone system?

Answer 26

Vasoconstriction mediated by angiotensin 2 raises TPR
Increased reabsorption of sodium from renal tubules results in an increase in water reabsorption down the resulting osmotic gradient, raising blood volume and cardiac output, elevates MAP

Question 27

Adrenaline causing an increase in cardiac output is mediated by which receptors?

Answer 27

B-adrenoceptors

Question 28

Noradrenaline causing vasoconstriction via which receptors to raise TPR?

Answer 28

A-adrenoreceptors

Question 29

What does atrial natriuretic peptide do?

Answer 29

Released in response to high cardiac filling pressures, reducing MAP by causing vasodilation and promotes Na+ excretion in kidneys