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Cardiovascular and Respiratory > Arterial system > Flashcards

Arterial system Flashcards

1
Q

why does the surface area of the vessels increase as you go peripherally?

A

it increases for exchange of gases

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2
Q

what are the three main layers of the arteries?

A
  • Tunica Intima
  • Tunica Media
  • Tunica Adventitia
    *
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3
Q

What is the contractile portion of the vascular wall?

A

tunica media

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4
Q

replacement of elastin by collagen in the arteries of the elderly happens at what layer of the artery?

A

Tunica Media

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5
Q

Elastic Recoil helps maintain what?

A

helps maintain flow in diastole

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6
Q

what section of vessels acts as the ‘control valves’ to the tissues?

A

the Arterioles

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7
Q

what happens to the smooth muscle cells when we increase pressure in vessels?

A

they contract - to maintain flow of blood at a steady rate

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8
Q

what is the difference between reactive and active hyperaemia?

A

reactive hyperaemia= after occlusion of blood flow (a tendency to hypoxia) - when you reinstate the blood flow you actually have an increased flow of blood to that tissue- because when you’re hypoxic metabolites like H+, lactic acid, and CO2 all accumulate in the area and temporarily increase blood flow to the tissue

Reactive hyperaemia = when you’re exercising and you require more oxygen to particular muscles, blood flow will increase

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9
Q

what is the myogenic mechanism of autoregulation of blood flow

A

increaed blood pressure in the vessels to another tissue - we don’t want the blood tissue to change drastically every time we move, so the vessels contract and maintains a normal blood flow to the area

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10
Q

What are the extrinsic regulators of peripheral blood flow?

A

parasympathetic and sympathetic mechanisms

sympathetic NS = alpha receptor activation on arterial smooth msucle celles mediate vasoconstriction

parasympathetics = absent in most tissues, but Ach causes NO dependent vasodilation

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11
Q

what is the Arterial Pulse?

A

Volume of blood ejected into arterial system results in

pressure rise transmitted as wave down arterial wall at

rate averaging about 7 m/sec. and felt as pulsation of

radial or other accessible artery

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12
Q

what is the maximum pressure called?

A

systolic = should be around 120mmHg

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13
Q

what is the pulse pressure?

A

it is systolic -diastolic

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14
Q

what causes the dicrotic notch (incisera)? on an arterial pressure trace

A

the ventricular valves close causing a backpressure causing a notch in the trace

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15
Q

how do you calculate the mean systemic arterial pressure?

A

= diastolic + 1/3 pulse pressure (to account for the notch)

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16
Q

what are the determinants of the arterial blood pressure?

A

preload (venous return)

heart rate

contractility

afterload (PR)

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17
Q

what law dictates the contractility of the left ventricle?

A

Starling’s law = stretched cardiac tissue will generate more force than resting cardiac tissue

18
Q

what do you call a drug that increases contractiliy?

A

postitive ionotrope

19
Q

What is the main determinant of afterload in the heart?

A

afterload = the pressure that the left ventricle has to overcome- therefore the afterload is determined by the pressure in the aorta or the peripheral resistance

therefore if we have an increased peripheral resistance the left ventricle must contract harder against it-

20
Q

what are the main determinants of diastolic pressure?

A

by the resistance to flow

21
Q

If the preload increases, does the afterload decrease?

A

yes

22
Q

what is the most immediate control of blood pressure?

A

baroreceptor reflex first

then it is the longterm control through the renal regulation of sodium and water homeostasis

23
Q

what are the baroreceptors?

A

sensory receptors that respond to stretch (mechanoreceptor)

24
Q

where are the baroreceptors located?

A

located in the aortic arch where the common carotid leaves

25
Q

stretching a baroreceptor has what effect on the nerve stimulation?

A

increases in both mean blood pressure &

pulse pressure increase rate of discharge in afferent

nerves

26
Q

The carotid sinus receptors are innervated by what nerve?

A

by the cranial nerve 9 and 10 (carotid sinus nerve)

27
Q

where do the baroreceptors signals communicate with in the brain?

A

the Medulla

28
Q

does increase in mean arterial blood pressure stretch or contract the baroreceptors?

A

stretch

29
Q

if you strech a baroreceptor - what occurs?

A

stimulates action potential to the medulla - then in the medulla a decision is made to inhibit the sympathetic signals - this leads to a decrease in outflow

30
Q

the action potentials from baroreceptors leads to what?

A

inhibition of sympathetics - therefore it leads to a dilation of the vessels and decrease resistance

31
Q

a decrease in mean arterial pressure has what effect on the baroreceptors action potential frequency?

A

leads to a decrease in the baroreceptor frequency - which leads to an increase in sympathetic activity

32
Q

what are some triggers for the baroreceptor reflex?

A

supine to upright position

lower body venous pooling

haemorrhage

decreased Blood volume

This leads to a decreased venous return, decreased output, decreased mean arterial pressure and therefore a baroreflex is triggered

33
Q

decreased systemic arterial blood pressure causes what state?

A

reflex tachycardia, increased force of ventricular contraction and constriction of veins and arterioles - increased diastolic blood pressure

34
Q

what is the pressure buffer system?

A

mean arterial pressure is around 95-100 mmHg normally - it’s the pressure we need to maintain to make sure our organs are nicely profused = therefore the job of the pressure buffer system is to make sure that we stay in this range -

35
Q

Which baroreceptors are more sensitive? Aortic or carotid?

A

the carotid are more sensitive

36
Q

in chronic situations of hypertension where the set point has changed, what occurs to the pressure buffer system?

A

it shifts the curve to the right - it thinks that the natural high blood pressure is ‘normal’

37
Q

describe from begining to end the effects on your heart rate/flow when you lay down

A
38
Q

what is a sphygomanometer?

A

it’s the old fashioned cuff and stethoscope

39
Q

what is an oscillometer?

A

observes oscillations in the sphygmomanometer cuff pressure - it uses a cuff still but with an electronic pressure sensor (transducer) to observe cuff pressure oscillations, electronics to automatically interpret them, and automatic inflation and deflation of the cuff

40
Q

what are the 1st, 2nd ,3rd and 4th heart sounds?

A

Cardiovascular and Respiratory (39 decks)

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