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I've got hypertension > Lecture 10 > Flashcards

Lecture 10 Flashcards

1
Q

Arterial pressure is _______ controlled and is precisely regulated at ________ mmHg

A

homeostatically controlled

90

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2
Q

Why is it important that the arterial pressure is maintained?

A

so that there is sufficient perfusion pressure to overcome the resistance of arterioles, while flowing at the desired rate

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3
Q

What does arterial pressure being homeostatically controlled enable?

A

it enables precise control of regional blood flow by manipulating only the regional resistance

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4
Q

What are the sensors of blood pressure and where are they located?

A

baroreceptors in the aortic arch and carotid sinus

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5
Q

Where is the carotid sinus? Why is it important that there are baroreceptors there?

A

This is in the neck. We need the blood pressure to be good here because this is going to the brain

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6
Q

Baroreceptors are ______ active at rest. What does this mean?

A

tonically

this means they have a resting firing rate that changes in response to high or low blood pressure

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7
Q

How do baroreceptors change in response to an increase in blood pressure?

A

If there is an increase in BP, there is an increase in stretch. This is detected by the baroreceptors and they increase their rate of firing

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8
Q

How do baroreceptors change in response to a decrease in blood pressure?

A

If there is a decrease in BP, there is a decrease in stretch. This is detected by the baroreceptors and they decrease their rate of firing

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9
Q

How do the baroreceptors in the aortic arch and carotid sinus send information to the brain?

A

The receptors in the carotid sinus send information via the carotid sinus nerve and the receptors in the aortic arch send information via the vagus nerve

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10
Q

What is another name for the carotid sinus nerve?

A

the glossopharyngeal nerve

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11
Q

Why is the pressure cyclical?

A

because it changes between systolic and diastolic pressure

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12
Q

Each cycle can give a burst of _______ activity of the nerve

A

tonic

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13
Q

Blood pressure regulation is needed for ______ term regulation such as ________ to _______

A

short

sitting to standing

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14
Q

As the blood pressure goes up, there is an increase/decrease in the rate of firing

A

increase

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15
Q

If you reduce your MABP, the amount of nerve activity is increased/decreased

A

decreased

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16
Q

If the MABP is increased, the amount of nerve activity is increased/decreased

A

increased

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17
Q

How can you increase pulse pressure?

A

through an increase in systolic and a decrease in diastolic pressure

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18
Q

If the pulse pressure increases, the amount of nerve activity is what?

A

very very large

19
Q

Where is the information about the firing from the baroreceptors processed?

A

in the integrator: the nucleus tractus solitarius (NTS) in the medulla

20
Q

The information from our nerves is coming up to the NTS and is doing what?

A

trying to work out if it is different from normal and then sends information out back to the periphery on how to change things to get things back to normal

21
Q

What is the efferent output from the NTS?

A

parasympathetic and sympathetic output (both pre-gangionlic and post-ganglionic nerves for this)

22
Q

Where is the cardiovascular sensor located?

A

in the medulla

23
Q

Describe the sympathetic output from the medulla

A

It comes out of the spinal cord and there is a synapse onto the preganglionic fibre which goes to a sympathetic ganglion just outside the spinal cord and then there is postganglionic fibres which innervate the heart and the blood vessels

24
Q

Describe the parasympathetic output from the medulla

A

The preganglionic fibre comes out of the medulla towards the heart and synapses in the ganglion in the heart and then the post-ganglionic fibre changes things in the heart

25
Q

What do parasympathetic nerves innervate and how does this affect MABP?

A

they innervate the heart which acts to reduce the flow/CO and this decreases MABP

26
Q

What do sympathetic nerves innervate and how does this affect the MABP?

A

Some of them innervate the heart which acts to increase flow/CO and some innervate the blood vessels which act to increase TPR and this increase MABP

27
Q

What happens when there is an increase in MABP?

A
  • arterial baroreceptors increase their firing
  • this decreases sympathetic outflow to the heart, arterioles and veins and
  • increase parasympathetic outflow to the heart
  • there is decreased contractility, decreased TPR, decreased HR, decreased MABP
28
Q

What happens when there is a decrease in MABP?

A
  • arterial baroreceptors decrease their firing
  • this decreases parasympathetic outflow to the heart and
  • increases sympathetic outflow to the heart, arterioles and veins
  • there is increased contractility, increased TPR, increased HR, increased MABP
29
Q

Defne a haemorrhage

A

an escape of blood from a ruptured blood vessel

30
Q

When you haemorrhage, your blood pressure decreases. What are the three stages of restoration?

A
  • baroreflex
  • cardiovascular volume restoration
  • total body volume restoration
31
Q

How does arterial blood pressure fall after a haemorrhage?

9

A
  • blood loss
  • decreased blood volume
  • decreased venous pressure
  • decreased venous return
  • decreased atrial pressure
  • decreased ventricular end-diastolic volume
  • decreased stroke volume (detected by baroreceptors)
  • decreased cardiac output
  • decreased arterial blood pressure
32
Q

How does the baroreflex act immediately to try and restore blood pressure after a haemmorhage?

A 
it acts on the heart to 
- increase HR
- increase SV
- increase CO
- increase MABP
it acts on the veins to 
- cause venoconstriction to
- increase VR
- increase EDV
- increase CO
- increase MABP
it acts on the arterioles to
- cause vasoconstriction to
- increase TPR
- increase MABP
33
Q

What is the issue with the baroreflex when you have haemorrhaged?

A

it does not restore blood volume

34
Q

Describe the cardiac volume restoration process in response to a haemorrhage?

A

If there is a reduction in pressure, an increase in vasoconstriction of the arterioles will lead to a bigger drop in pressure across the arterioles so the capillary pressure is lower.
In the normal capillary pressure, H2O tends to be driven out of the capillary but after the haemorrhage there is a change in pressure and so instead of water leaving the capillaries, water enters the capillaries which restores blood volume

35
Q

What is the purpose of the cardiovascular volume restoration function?

A

If we have a reduction in MABP, we can pull water into the capillaries

36
Q

Where are large amounts of water absorbed in the body?

A

from the skin and the gut (non-vital places)

37
Q

How long does blood pressure take to be restored after water is pulled from the capillaries?

A

just a few minutes

38
Q

What is the long-term total body volume restoration system?

A

this is the renin angiotensin aldosterone system

39
Q

Describe the renin angiotensin aldosterone system

A
  • the kidneys produce renin and the liver produces angiotensinogen
  • the renin converts the angiotensinogen to angiotensin |
  • enzymes in the lungs and blood vessels called angiotensin converting enzymes convert angiotensin | to angiotensin ||
  • angiotensin || causes vasoconstriction which can help with the maintenance and BP
  • angiotensin || also acts on the adrenal cortex and kidney to produce aldosterone
40
Q

What is the effect of aldosterone?

A

it stimulates Na+ and H2O reabsorption in the kidney which decreases urine output and increase total body water

41
Q

What is renin production controlled by?

A
  • regulated by perfusion pressure (reduction in this leads to increase in renin production)
  • sympathetic stimulation (via the baroreflex)
42
Q 
Which statement is INCORRECT? An increase in sympathetic nerve activity will :
A) Decrease heart rate
B) Increase venous return
C) Increase ventricular contractility
D) Increase the production of renin
A

A) Decrease heart rate

43
Q

The baroreceptors are tonically inactive at rest BECAUSE at rest arterial blood pressure is maintained at approximately 120/80 mmHg to silence the baroreceptors.

A

false, false

I've got hypertension (47 decks)

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