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Phys, pharm > Regulation of blood pressure > Flashcards

Regulation of blood pressure Flashcards

1
Q

What is ‘stressed volume’?

A

The volume of blood in the arteries
Blood under high pressure

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2
Q

Where do arteries receive blood from?

A

Directly from the heart

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3
Q

Describe the structure of an artery

A

Thick muscular ring
Folded parts enable stretching

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4
Q

Name 3 things which can change the rate of blood flow in arterioles

A
  1. SNS causing contraction of vsm
  2. Circulating catecholamines (adrenaline)
  3. Vasoactive substances (NO)
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5
Q

Define tonically active

A

Constant muscle tone

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6
Q

Structure of arterioles

A

Smaller blood vessels
Round with vascular smooth muscle

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7
Q

What are capillaries controlled by?

A

Pre capillary sphincters
Dilation/constriction of arterioles

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8
Q

Which blood vessel has more elastic tissue in their walls?

A

Venules and veins

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9
Q

Which blood vessel has the largest percentage of blood in the cv system?

A

Venules and veins

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10
Q

How do alpha 1 adrenergic receptors interact with veins and venules?

A

Vasoconstriction due to reduced capacitance leading to a decrease in ‘unstressed volume’

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11
Q

What is the equation for velocity of blood flow?

A

V = Q/A
V = velocity of blood flow (cm/s)
Q = flow (ml/s)
A = cross sectional area (cm2)

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12
Q

What is the relationship between velocity and cross-sectional area in identical flow?

A

An inverse relationship

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13
Q

What is the equation for the relationship between blood flow, resistance and pressure?

A

Q = DeltaP/R
Q= flow (ml/s)
DeltaP = Pressure difference (mmHg)
R = Resistance (mmHg/ml per min)

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14
Q

What is total peripheral resistance?

A

Resistance of an entire systemic vasculature

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15
Q

What is the equation for Poiseille’s law?

A

R = 8nl/(Pi)r4
R= resistance
n = blood viscosity
l = length of blood vessel
(pi) r4 = radius of the blood vessel (to the power of 4)

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16
Q

What factors contribute to blood flow resistance?

A

Blood vessel diameter
Vessel length
Parallel/series arrangement
Blood viscosity

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17
Q

What is the relationship between resistance to flow, vessel length and blood viscosity?

A

Resistance to flow is directly proportional to vessel length and blood viscosity

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18
Q

What is haemocrit?

A

% of rbc in a sample

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19
Q

How to calculate the total resistance in a series vessel arrangement?

A

Sum of all the individual resistances

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20
Q

What happens to pressure as you move through a series arrangement?

A

Pressure decreases through each sequential component

21
Q

How to calculate total resistance in a parallel vessel arrangement

A

1/Rx
x= sequential components

22
Q

What is an advantage of a parallel series?

A

No loss of pressure so blood can perfuse sufficiently

23
Q

What happens to the pressure as the blood flows? Why?

A

Pressure decreases
- energy is lost due to frictional resistance

24
Q

How does the pressure in the aorta change with age?

A

High proportion of elastin decreases with age therefore, compliance decreases

25
Q

What is a dicrotic notch? What can it cause?

A

The closure of the aortic valve between systole and diastole
Can cause slight backflow

26
Q

When is arterial pressure at its lowest? (diastolic pressure)

A

Ventricular relaxation

27
Q

When is arterial pressure at its highest? (systolic pressure)

A

Ventricular ejection during contraction

28
Q

What is the equation for pulse pressure?

A

Pulse pressure = systolic - diastolic pressure

29
Q

What does pulse pressure show?

A

Blood volume ejected from the left ventricle (stroke volume)

30
Q

What is the equation for mean arterial pressure?

A

Mean arterial pressure = diastolic pressure + 1/3 pulse pressure

31
Q

What does mean arterial pressure show?

A

Average pressure in a cardiac cycle

32
Q

How does blood pressure change throughout the day?

A

Systolic bp is always higher than diastolic
Day > Night
Highest in the hours when just waking up

33
Q

What are the 2 baroreceptors?

A

Carotid sinus
Aortic sinus

34
Q

Describe the rapid regulation of blood pressure.

A

Solitary nucleus receives input from cranial nerve IX (carotid) and X (aortic) ->
PNS outflow via vagus nerve to SAN causes decresae in HR and BP
OR
SNS to SAN causes
1. An increase in hr
2. Increase in cardiac muscle contractility&sv
3. Arteriole vasoconstriction = increase in TPR
4. Vein vasoconstriction = decrease in unstressed volume

35
Q

Where is the solitary nucleus located?

A

Medulla

36
Q

What is renin?

A

A factor which converts angiotensinogen to angiotensin 1

37
Q

Describe medium/long term control of arterial p

A

RAAS (renin, angiotensin, aldosterone) system regulates blood volume ->
A decrease in arterial pressure = decrease in renal prefusion (prorenin to renin) ->
Renin converts angiotensinogen to angiotensin 1 ->
Angiotensinogen converting enzyme converts angiotensin 1 to angiotensin 2

38
Q

What are the effects of angiotensin 2 in the adrenal cortex?

A

Causes aldosterone synthesis and secretion causing an increase in Na+ reabsorption ->
Stimulates Na+ - H+ exchange within the kidney and Na+ + HCO3 reabsorption

39
Q

What are the effects of angiotensin 2 iin the hypothalamus?

A

Increase in thirst and ADH secretion leading to an increase in water reabsorption in collecting ducts
Vasoconstriction of arterioles leading to an increase in TPR

40
Q

What is the effect of O2 and CO2 detection in the carotid and aortic sinus chemoreceptors?

A

Arteriole vasoconstriction

41
Q

What do V1 receptors control?

A

Vascular smooth muscle cells -> vasoconstriction

42
Q

What do V2 receptors control?

A

CD -> water retention

43
Q

What does Atrial natriuretic peptide do?

A

Powerful vasodilator
Increases diuresis
Decreases circulating volume

44
Q

What carries info from carotid sinus to brain stem?

A

Cranial nerve IX

45
Q

What carries info from aortic sinus to brain stem?

A

Cranial nerve X

46
Q

What happens to baroreceptors in hypertension?

A

Baroreceptors reset therefore hypertension isn’t corrected but maintained

47
Q

Name 5 risks of persistent high bp

A

Heart attacks
Strokes
Aortic aneurysms
Kidney disease
Vascular dementia

48
Q

Name 5 hypertension treatments

A

ACE inhibitors
Angiotensin II receptor blockers
Diuretics
Beta-blockers
Renin inhibitors

Phys, pharm (31 decks)

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