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Physiology 2 (Y2,S2) > CVS 2: Cardiac Cycle & Regulation of Cardiac Output > Flashcards

CVS 2: Cardiac Cycle & Regulation of Cardiac Output Flashcards

1
Q

what does the P wave result from

A

atrial depolarisation

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2
Q

what does the QRS wave result from

A

ventricular depolarisation

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3
Q

what does the T wave result from

A

ventricular repolarisation

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4
Q

T/F?: the QRS wave is due to atrial depolarisation

A

False.
QRS wave due to ventricular depolarisation (P wave due atrial depolarisation) .

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5
Q

what is systole

A

phase of contraction

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6
Q

what is diastole

A

phase of relaxation

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7
Q

T/F?: blood flows from region of low pressure to region of high pressure

A

False.
Blood flows from area of high pressure to area low pressure

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8
Q

describe atrial/ventricular diastole

A
  • both atria & ventricles are relaxed
  • AV valves & semilunar valves closed
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9
Q

venous return comes from where & does what

A
  • venous return of blood fills both atria
  • vena cava into right atrium
  • pulmonary vein into left atrium
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10
Q

T/F?: ventricles become 70% filled during ventricular filling phase

A

false.
Ventricles become 80% filled during this phase

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11
Q

describe atrial systole

A
  • spontaneous depolarisation in SA node passes into surrounding atria (P wave)
  • depolarisation & contraction of atrial myocardial cells
  • both atria contract, ventricles still relaxed
  • final 20% blood pumped into ventricles through AV valves
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12
Q

what is EDV

A
  • end diastolic volume
  • ventricles now full of blood (end of atrial systole)
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13
Q

T/F?: the repolarisation of atrial myocytes & the depolarisation of ventricular myocytes causes the QRS wave

A

True !

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14
Q

when do the AV valves close

A

when the ventricular pressure is greater than the atrial pressure

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15
Q

T/F?: semilunar valves open when the pressure in the pulmonary arteries rises above pressure in the right ventricles

A

False.
Semilunar valves open when pressure in right vent. becomes higher than pressure in pulmonary artery

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16
Q

what is the stroke volume

A

vol of blood ejected from ventricles during ventricular systole

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17
Q

T/F?: ventricles eject 100% of the blood they contain in ventricular systole

A

False.
both ventricles eject two thirds of the blood they contain (stroke vol)
one third vol left (end systolic vol)

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18
Q

when do the semilunar valves close

A

pressure in ventricles falls below that of pulmonary artery & aorta

19
Q

describe the end of the cardiac cycle (atrial/ventricular diastole)

A
  • ventricle myocaridal cells repolarise (T wave)
  • AV & semilunar valves closed
  • atria filling w venous blood so atrial pressure rises
  • ventricular pressure falling (diastole)
  • when atrial pressure is greater than ventricular pressure, the AV valves open & cardiac cycle begins again
20
Q

T/F?: AV valves open when ventricular pressure is greater than atrial pressure

A

False.
Av valves open when atrial pressure is greater than ventricular pressure

21
Q

how long does systole take

A

0.3 seconds

22
Q

how long does diastole take

23
Q

what creates the lub sound

A

blood turbulance caused by the closure of the AV valves as systole begins

24
Q

what creates the dub sound

A

blood turbulence from closing of the semilunar valves at beginning of diastole

25
T/F?: movement of the stroke vol closes semilunar valves
true
26
what is EDV & value
* end diastolic volume is the volume of blood in ventricles at the end of diastole * EDV = 135ml
27
what is ESV & what value
* end systolic volume is the volume of blood in the ventricles at the end of systole * ESV = 60ml
28
what is stroke vol & value
* stroke volume is the vol of blood ejected by each ventricle during systole * EDV - ESV = 75ml
29
T/F?: to calculate stroke volume EDV and ESV must be added
False. stroke volume = EDV - ESV
30
how to calculate cardiac output
cardiac output = stroke volume x cardiac rate
31
what is cardiac output at rest
5.5 litre/min
32
what can heart rate and stroke vol both be modulated by
the autonomic nervous system
33
T/F?: autonomic nervous system includes volunatary movements
False. Involuntary only
34
T/F?: sympathetic & parasympathetic nerves often innervate the same tissue/organ
True
35
what kind of effects do noradrenaline (sympathetic division) & acetlycholine (parasympathetic division) have on the activity of the tissue/organ
Opposing effects - stimulatory vs. inhibitory effects
36
what nerve controls AV & SA nodes
vagus nerve (parasympathetic)
37
what do sympathetic cardiac nerves innervate
1. SA node 2. AV node 3. Ventricular myocardial cells
38
what is neural regulation of cardiac rate performed by
the sympathetic & parasympathetic division of the autonomic nervous system
39
T/F?: the rate of depolarisation in the AV node sets rate of depolarisation of contractile myocardial cells
false. rate of depolarisation in SA node sets rate of depolarisation
40
how does noradrenaline increase heart rate
* released by sympathetic nerve endings * binds to beta adrenergic receptors * stimulates opening of Na+ and Ca2+ channels (HCN channels) in pacemaker cells of SA node * HCN channels trigger depolarisations * increased opening = increased generation of APs = increased heart rate
41
how does acetylcholine decrease heart rate
* parasympathetic nerve releases acetylcholine * binds to muscarinic acetylcholine receptors on SA node cells * opens K+ channels * hyperpolarises cell membrane (more neg-repolarisation) * decreased AP generation * inhibits opening of HCN channels
42
T/F?: acetylcholine binds to beta adrenergic receptors in SA node
False. Binds to muscarinic acetylcholine receptors on SA node cells
43
T/F?: noradrenaline decreases opening of of HCN channels
False. Acetylcholine inhibits HCN opening, noradrenaline promotes it.
44
T/F?: increase in contractility increases the stroke vol
True increased EDV stretches the ventricular muscle cells causing increased force of contractility of these cells

Physiology 2 (Y2,S2) (3 decks)

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