Short Term Control of BP

Question 1

What is the baroreflex responsible for?

Answer 1

Maintenance of arterial blood pressure

Question 2

How many sets of baroreflexes do we have?

Answer 2

2

Question 3

Where can you find the baroreflexes?

Answer 3

Aortic arch
Carotid sinuses

Question 4

What do the aortic arch and carotid sinuses have in common?

Answer 4

Both stretchy

Question 5

How do the baroreceptors detect changes in pressure?

Answer 5

When pressure increases, the walls stretch and baroreceptors detect that change in stretch and they increase the firing rate of action potentials.

Question 6

What happens to the firing rate of action potentials when pressure increases?

Answer 6

Firing rate increases

Question 7

What happens to the firing rate of action potentials when pressure decreases?

Answer 7

Firing rate decreases

Question 8

When are the aortic arch and carotid sinuses stretched the most?

Answer 8

During systole as there is an increase in pressure.

Question 9

Where do the aortic arch baroreceptors send their signal?

Answer 9

Up the Vagus nerve

Question 10

Where do the carotid sinuses send their signals?

Answer 10

Up the glossopharyngeal nerve.

Question 11

Where are the integrating centres known as the medullary cardiovascular centres located?

Answer 11

Medulla oblongata

Question 12

Name some of the responses that the medullary cardiovascular centres can evoke to bring MAP back to where it should be.

Answer 12

Parasympathetic outflow via vagus nerve
Sympathetic nerves

Question 13

Which neurotransmitter is released in a parasympathetic response?

Answer 13

Acetyl choline

Question 14

Where does acetyl choline bind to?

Answer 14

Cholinergic muscarinic receptors on the pacemaker cells.

Question 15

What will happen when acetyl choline binds to the cholinergic muscarinic receptors on the pacemaker cells?

Answer 15

Cause them to hyperpolarise and will take them longer to reach threshold therefore decreasing HR.

Question 16

Describe the sympathetic nerve response.

Answer 16

Release of noradrenaline which binds to beta-1 receptors causing pacemaker cells to depolarise faster and it will therefore increase heart rate.

Question 17

Describe the sympathetic nerves which innervate the muscle of the ventricle.

Answer 17

Increased contractibility,.
Greater release of calcium causing more cross bridging of myosin and actin filaments, increasing the contraction and stroke volume.

Question 18

List some of the other outputs to the cardiovascular centres.

Answer 18

Cardiopulmonary baroreceptors
Central chemoreceptors
Chemoreceptors in muscle
Joint receptors
Higher centres

Question 19

What do cardiopulmonary baroreceptors do?

Answer 19

Sense central blood volume

Question 20

What do central chemoreceptors do?

Answer 20

Sense changes in the partial pressures of oxygen and CO2

(guessing this is revision for resp. lectures…whoops? vaguely rings a bell ig)

Question 21

What do chemoreceptors in muscles do?

Answer 21

Sense changes in metabolite concentration

Question 22

What do joint receptors do?

Answer 22

Sense joint movement

Question 23

Give two examples of higher centre.

Answer 23

Hypothalamus
Cerebral cortex

Question 24

What is the hypothalamus responsible for?

Answer 24

Coordinating vascular responses for thermoregulation.
Also involved in flight or fight response.

->f you’re too hot then it will tell the medullary cardiovascular system to vasodilate.

Question 25

What is the Valsalva Manoeuvre

Answer 25

Forced expiration against a closed glottis ->forcefully expiring with your mouth closed

Question 26

What happens in stage one of the Valsalva Manoeuvre?

Answer 26

Increased thoracic pressure is transmitted through to aorta - immediate increase in BP

Question 27

What happens in stage two of the Valsalva Manoeuvre?

Answer 27

Increased thoracic pressure reduces the filling pressure from the veins, which therefore ↓ VR, ↓ EDV, ↓ SV, ↓ CO, ↓ MAP

Question 28

What happens in the late stage two of the Valsalva Manoeuvre?

Answer 28

The reduced MAP is detected by baroreceptors which initiate a reflex increase in CO and TPR

Question 29

What happens in stage three of the Valsalva Manoeuvre?

Answer 29

At end of the manoeuvre, the decrease in thoracic pressure is transmitted through to the aorta, hence the drop in BP

Question 30

What happens in stage four of the Valsalva Manoeuvre?

Answer 30

VR is restored so SV ↑, but reflex effects have not worn off

Question 31

What function test can the Valsalva Manoeuvre be used for?

Answer 31

Test of autonomic function

Question 32

In which individuals may the Valsalva Manoeuvre be reduced?

Answer 32

Elderly Individuals w autonomic neuropathy* *when nerves have been damaged, sometimes due to diabetes

Question 33

Sometimes performing the Valsalva Manoeuvre can be dangerous. What can it cause?

Answer 33

Can increase risk of myocardial infarction