Short Term Control of BP Flashcards

1
Q

What is the baroreflex responsible for?

A

Maintenance of arterial blood pressure

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2
Q

How many sets of baroreflexes do we have?

A

2

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3
Q

Where can you find the baroreflexes?

A

Aortic arch
Carotid sinuses

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4
Q

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

A

Both stretchy

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5
Q

How do the baroreceptors detect changes in pressure?

A

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

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6
Q

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

A

Firing rate increases

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7
Q

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

A

Firing rate decreases

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8
Q

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

A

During systole as there is an increase in pressure.

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9
Q

Where do the aortic arch baroreceptors send their signal?

A

Up the Vagus nerve

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10
Q

Where do the carotid sinuses send their signals?

A

Up the glossopharyngeal nerve.

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11
Q

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

A

Medulla oblongata

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12
Q

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

A

Parasympathetic outflow via vagus nerve
Sympathetic nerves

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13
Q

Which neurotransmitter is released in a parasympathetic response?

A

Acetyl choline

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14
Q

Where does acetyl choline bind to?

A

Cholinergic muscarinic receptors on the pacemaker cells.

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15
Q

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

A

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

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16
Q

Describe the sympathetic nerve response.

A

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

17
Q

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

A

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

18
Q

List some of the other outputs to the cardiovascular centres.

A

Cardiopulmonary baroreceptors
Central chemoreceptors
Chemoreceptors in muscle
Joint receptors
Higher centres

19
Q

What do cardiopulmonary baroreceptors do?

A

Sense central blood volume

20
Q

What do central chemoreceptors do?

A

Sense changes in the partial pressures of oxygen and CO2

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

21
Q

What do chemoreceptors in muscles do?

A

Sense changes in metabolite concentration

22
Q

What do joint receptors do?

A

Sense joint movement

23
Q

Give two examples of higher centre.

A

Hypothalamus
Cerebral cortex

24
Q

What is the hypothalamus responsible for?

A

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.

25
Q

What is the Valsalva Manoeuvre

A

Forced expiration against a closed glottis

->forcefully expiring with your mouth closed

26
Q

What happens in stage one of the Valsalva Manoeuvre?

A

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

27
Q

What happens in stage two of the Valsalva Manoeuvre?

A

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

28
Q

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

A

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

29
Q

What happens in stage three of the Valsalva Manoeuvre?

A

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

30
Q

What happens in stage four of the Valsalva Manoeuvre?

A

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

31
Q

What function test can the Valsalva Manoeuvre be used for?

A

Test of autonomic function

32
Q

In which individuals may the Valsalva Manoeuvre be reduced?

A

Elderly
Individuals w autonomic neuropathy*

*when nerves have been damaged, sometimes due to diabetes

33
Q

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

A

Can increase risk of myocardial infarction