L25 (pathophysiology) Flashcards

1
Q

does the heart spend more time in diastole or systole

at rest?
during exercise?
what effect does this have on MAP

A

at rest diastole however during exercise it is systole

this means that MAP is closer to the diastolic pressure than the systolic pressure

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2
Q

what is the equation for MAP

A

DAP + 1/3(SAP-DAP)

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3
Q

define hypertension

A

high arterial blood pressure at rest

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4
Q

what is the range for prehypertension/elevated blood pressure

A

SAP = 120-129mmHg

DAP < 80

therefore it is when only SAP has increased

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5
Q

what is the range for stage 1 and stage 2 hypertension

A

stage 1

  • SAP = 130-139
  • DAP = 80-89

stage 2

  • SAP >140
  • DAP > 90

for both stage 1 and 2 you only need to have in increase in diastolic or systolic pressures

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6
Q

what is the prevalence of hypertension in NZ

and why could this be underestimated

A

21.4% of NZders or 1:5
this means 1 million people in NZ have hypertension

this could be underestimated because it is only including people that are taking medication to reduce their blood pressure and not everyone knows that they have it and if they have it it doesn’t mean that they ae on medication for it

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7
Q

what is hypertensions relationship with age and gender

A

the prevalence increases with age

there is no difference between gender

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8
Q

what is the main cause of hypertension

A

TPR

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9
Q

what determins TPR

A

Vessels in series and parallel determine TPR

resistance cant cause resistance

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10
Q

where is the largest pressure drop

A

Largest pressure drop
in small arteries and arterioles
(resistance vessels)

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11
Q

what are the physical factors that cause hypertension

A

Arterial blood volume increase

Arterial compliance decrease

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12
Q

how is arterial blood volume regulated

A

by the kidney in the long term

osmoreceptors detect increased osmotic pressure causing the release of ADH from posterior pituitary which acts on the blood vessels causing vasoconstriction-> increased BP

baroreceptors in the aortic arch and carotid sinus detect blood pressure, this causes ADH to be released from the posterior petuitory which acts on the kidney to increase water reabsorption which leads to increased blood volume and pressure

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13
Q

what is the difference between Arteriosclerosis and Atherosclerosis

A

aRterIosclerosis = disease of the media and alters the stiffness of the vessels (media thickening)

atherOsclerosis = disease of the intam which alters the conduct (blockage)

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14
Q

define aRterIosclerosis

A

disease of the media and alters the stiffness of the vessels

Media thickening in large or resistance arteries
Increasing stiffness of the arteries

happens because of hypertension (ageing)

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15
Q

define atherOsclerosis

A

disease of the intam which alters the conduct

Changes of the intima causing blockage of the arteries (plaque formation)

caused by Coronary and peripheral artery disease

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16
Q

describe the relationship between arterial compliance and age

A

older people have less arterial compliance

when pressure increases in the vessels that do not expand as much

Less compliant vessels with age - reduced arterial compliance = hypertension

17
Q

whoops

18
Q

why does hypertension increase with age

A

as you age the vessel wall has less and less elastin and more collagen

the collagen that you get with ageing is different to the normal collagen in the wall as this collagen is stiffer as it makes more crosslinks

collagen is 1000x stiffer than elestin therefore with the increase in collagen and the decrease in elestin you REALLY increase the stiffness of the arterial wall increasing peripheral resistance therefore causing hypertension

19
Q

describe collagen as we age

A

the collagen that you get with ageing is different to the normal collagen in the wall as this collagen is stiffer as it makes more crosslinks

collagen is 1000x stiffer than elestin therefore with the increase in collagen and the decrease in elestin you REALLY increase the stiffness of the arterial wall causing increase in resistance

20
Q

normal blood pressure is 120/80

Elevation in peripheral vascular resistance
(due to decrease in arterial compliance) can increase the systolic and diastolic pressures by how much

A

DAP + 10-40 mmHg

SAP + 50-100 mmHg

21
Q

what are flow waves

A

they are generated by the heart in systole when it pumps out blood

flow waves are the flow of blood

22
Q

In systole, flow waves are generated by the heart

what is their relationship with the compliance of the aorta

A

Storage of stroke volume in conduit vessels – distensibility of aorta

In diastole, recoil of aorta maintains capillary flow

23
Q

describe flow waves in the aorta vs the capillaries

why is this

A

Pulsatile flow into the aorta, but continuous/constant flow through the capillaries

Compliance of the aorta is essential to dampen the pulsatile flow wave of the heart

24
Q

in hypertension the systolic pressure increases more than the diastolic pressure, why is this

A

The aorta is the major contributor for dampening the pulsatility of the heart

With hypertension the aorta becomes stiffer therefore there is not storage of SV during systole. once the valve closes then there is no flow through the aorta as there is little elastic recoil

Therefore the aorta becomes less flexible with age which increases and decrease the pressure therefore creating pulsatile flow

25
what is hypertensions effect on gas exchange in the capillaries
it causes the capillary flow to become pulsatile which is bad for exchange (decreases it) this is because the aorta is not acting as an elastic reservoir
26
During systemic hypertension, the compliance of the aorta: A. decreases, which decreases the pulsatility of blood flow through the capillaries. B. decreases, which increases the pulsatility of blood flow through the capillaries. C. increases, which decreases the pulsatility of blood flow through the capillaries. D. increases, which increases the pulsatility of blood flow through the capillaries.
B
27
what is a pulse wave
they are generated by the heart, independent of blood flow (not a flow wave) this is the contraction moving through the wall of the vessel
28
what are the velocity values of a flow wave compared to a pulse wave
flow wave = 0-20cm/s pulse wave 2-12m/s note PW is in m/s and flow is cm/s
29
in the aorta how many x faster is the pulse wave compared to the flow
100x
30
what happens when a pulse wave hits a bifurcation
a reflection wave is formed
31
describe the forward and reflected wave
these are both pulse waves when the forward wave his a bifurcation it forms a reflected wave which moves in the opposite direction the reflected wave is always slightly behind the forward wave
32
what is the observed wave
it is the combonation of the forward and the reflected wave this is what you measure when you are taking blood pressure
33
Proximal vessels compliant whereas the Distal vessels are stiffer what does this mean in terms of the pulse waves
Pulse wave travels faster in distal than proximal vessels Aorta 3-5 m/s Radial artery 5-12 m/s this is because the stiffer the vessel the faster the wave
34
what does the diffeent stiffness of the vessels mean fo the observed blood pressure
Distal vessels are stiffer (faster pulse wave) they have larger contribution of reflections compared to proximal vessels meaning that the pressure in the distal arteries will be slightly higher this is a minor difference (5-10mmHg) compared to the classification of hypertension which has ranges of 20mmHg (therefore you don't have to worry about it that much)
35
describe pulse wave velocity as we age
Reduced compliance of conduit arteries increases pulse wave velocity higher contribution of reflected wave The observed wave will be higher because of stiff arteries which they will contribute more to reflection
36
who does the reflected wave being faster increase the observed wave (and therefore BP)
the more the waves overlap the more they add together when the wave is faster it adds together with the forward wave more
37
in compliant vessels what happens when the reflected wave is reflected back to the heart
normally when the reflected wave reaches the heart the valves are closed therefore it contributes to when the reflected wave comes back in increases the BP slightly and enters the coronary circulation
38
in hypertension what happens when the reflected wave is reflected back to the heart
As the arteries become more stiff there is a greater observed wave and pulsatility of the capillaries. This means that the reflected wave will be reflected back before the valves close which will increase afterload. the coronary blood supply is affected in this as well
39
The pulse wave velocity of the aorta decreases with older age BECAUSE at older age remodeling of the arterial wall results in a faster reflected pulse wave
the first statement should say increases therefore the first statment is incorrect and the second statment is correct