Physiology Flashcards

1
Q

how does digoxin affect heart contractility

A

inhibits Na/K pump which increases intracellular Na – > decreasing Na/Ca pump = increase intracellular Ca

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2
Q

Laplace law

A

wall tension = pressure x radius
wall stress = pressure x radius / 2x wall thickness

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3
Q

mid-late diastolic murmur

A

mitral stenosis

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4
Q

early disatolic murmur

A

aortic regurgitation

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5
Q

continuous machinery murmur

A

patent ductus arteriosus

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6
Q

ejection systolic murmur

A

aortic stenosis

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7
Q

holoystolic high pitched ‘blowing’ murmur

A

mitral/tricuspid regurgitation

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8
Q

late crescendo murmur with midsystolic click

A

mitral valve prolapse

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9
Q

holosystolic, harsh sounding murmur

A

Ventricular septal defect

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10
Q

Phase 0 of cardiac cell cycle

A

phase - rapid depolarisation as voltage gated Na channels open

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11
Q

phase 1 of cardiac action potential

A

initial replarisation - inactivation of voltage gated Na channels. voltage gated K channels begin to open

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12
Q

phase 2 of cardiac action potential

A

plateau due to influx of Ca which balances K efflux. Ca influx triggers Ca release from sarcoplasmic reticulum and myocyte contraction

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13
Q

phase 3 of cardiac action potential

A

rapid repolarisation - massive k efflux through opening of voltage gated slow delayed-rectifier K channels and closure of voltage gated ca channels

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14
Q

phase 4 of cardiac action potential

A

resting potential, high K permeability through K channels

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15
Q

main differences in pacemaker action potential to myocardial action potential

A

pacemaker action potential occurs in SA and AV node

phases 1 and 2 are absent

phase 0 - due to opening of voltage gated Ca channels as K channels permenantly inactivated

phase 3 due to inactivation of Ca channels and activation of K channels

phase 4 due to slow spontaneous depoarisation of If funny current channels.

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16
Q

what condition might you find u wave on ECG

A

hypokalaemia

17
Q

ANP is released in response to what

A

increased blood volume and atrial pressure

18
Q

what does ANP act via

A

cGMP

19
Q

effects of ANP

A

reduced Na reabsorption in the renlal collecting tubule
dilates afferent arteriole and constricts efferent arterioles promoting diuresis

20
Q

what has a longer half life, ANP or BNP

A

BNP

21
Q

effects of BNP

A

similar to ANP but has longer half life
released in response to increased tension

22
Q

aortic arch receptors act via what nerve

A

vagus nerve

23
Q

carotid sinus acts via what nerve

A

gossopharyngeal

24
Q

how can COPD result in patients requiring a lower oxygen sats target

A

C02 retainers rely on a high C02 in order to drive respiration.
Central chemoreceptors canbecome desensitized to chronic c02 levels and so they rely on peripheral chemoreceptors which respond to increased c02 levels

25
Q

in what conditon might pulmonary capillary wedge pressure (PCWP) may be an inaccurate measurement of left atrial pressure?

A

mitral stenosis
as the PCWP is > lv END DIASTOLIC PRESURE

26
Q

what does pulmonary capillary wedge pressure measure and how is it measured

A

measures left atrial pressure
- pulmonary artery catheter (Swanz-Ganz catheter)

27
Q

what is the difference in autoregulation with the lungs vs other organs in the body

A

alveolar hypoxia causes vasoconstriction so that well-ventilated areas are perfused
in other organs, hypoxia causes vasodilatation

28
Q

physiology of how pulmonary oedema occurs in HF

A

increase in capillary hydrostatic pressure

29
Q

what is responsible for determining the heart rate

A

the SA node which is determined by the cyclic nucleotide gated If funny channels

30
Q

wide and fixed S2 on examination

A

ASD

31
Q

head bobbing can be found in what valve disease and what murmur would it have

A

aortic regurgitation
early diastolic

32
Q

murmur that increases is intensity with inspiration

A

tricuspid stenosis

33
Q

murmur which may cause hoarseness and how

A

mitral stenosis
causes atrial enlargement = impingement of recurrent laryngeal nerve

34
Q

murmur that would increase and decrease on squatting

A

increase = aortic stenosis
decrease = HOCM and mitral regurgitation

squatting increases venous return which increases preload

35
Q

murmur that would decrease on valsalva maeuvre and how

A

aortic stenosis
valsalva decreases preload which decreases cardiac output

36
Q

murmur that would increase and decrease in intensity with handgrip

A

decrease - aortic stenosis
increase - aortic and mitral regurgitation

handgrip increases afterload which increases intensity of blood regurgitating back into the heart but would dampen stenosis

37
Q

effects of increased pulmonary vascular resistance

A

increased right ventricular straight –> right ventricular hypertrophy

38
Q

effects of increased left atrial strain

A

i.e. mitral stenosis
= increase in pulmonary capillary wedge pressure

39
Q

angioedema occurs due to the accumulation of what substance

A

bradykinin