Physiology

Question 1

how does digoxin affect heart contractility

Answer 1

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

Question 2

Laplace law

Answer 2

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

Question 3

mid-late diastolic murmur

Answer 3

mitral stenosis

Question 4

early disatolic murmur

Answer 4

aortic regurgitation

Question 5

continuous machinery murmur

Answer 5

patent ductus arteriosus

Question 6

ejection systolic murmur

Answer 6

aortic stenosis

Question 7

holoystolic high pitched ‘blowing’ murmur

Answer 7

mitral/tricuspid regurgitation

Question 8

late crescendo murmur with midsystolic click

Answer 8

mitral valve prolapse

Question 9

holosystolic, harsh sounding murmur

Answer 9

Ventricular septal defect

Question 10

Phase 0 of cardiac cell cycle

Answer 10

phase - rapid depolarisation as voltage gated Na channels open

Question 11

phase 1 of cardiac action potential

Answer 11

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

Question 12

phase 2 of cardiac action potential

Answer 12

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

Question 13

phase 3 of cardiac action potential

Answer 13

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

Question 14

phase 4 of cardiac action potential

Answer 14

resting potential, high K permeability through K channels

Question 15

main differences in pacemaker action potential to myocardial action potential

Answer 15

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.

Question 16

what condition might you find u wave on ECG

Answer 16

hypokalaemia

Question 17

ANP is released in response to what

Answer 17

increased blood volume and atrial pressure

Question 18

what does ANP act via

Answer 18

cGMP

Question 19

effects of ANP

Answer 19

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

Question 20

what has a longer half life, ANP or BNP

Answer 20

BNP

Question 21

effects of BNP

Answer 21

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

Question 22

aortic arch receptors act via what nerve

Answer 22

vagus nerve

Question 23

carotid sinus acts via what nerve

Answer 23

gossopharyngeal

Question 24

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

Answer 24

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

Question 25

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

Answer 25

mitral stenosis as the PCWP is > lv END DIASTOLIC PRESURE

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

Question 28

physiology of how pulmonary oedema occurs in HF

Answer 28

increase in capillary hydrostatic pressure

Question 29

what is responsible for determining the heart rate

Answer 29

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

Question 30

wide and fixed S2 on examination

Answer 30

ASD

Question 31

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

Answer 31

aortic regurgitation early diastolic

Question 32

murmur that increases is intensity with inspiration

Answer 32

tricuspid stenosis

Question 33

murmur which may cause hoarseness and how

Answer 33

mitral stenosis causes atrial enlargement = impingement of recurrent laryngeal nerve

Question 34

murmur that would increase and decrease on squatting

Answer 34

increase = aortic stenosis decrease = HOCM and mitral regurgitation squatting increases venous return which increases preload

Question 35

murmur that would decrease on valsalva maeuvre and how

Answer 35

aortic stenosis valsalva decreases preload which decreases cardiac output

Question 36

murmur that would increase and decrease in intensity with handgrip

Answer 36

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

Question 37

effects of increased pulmonary vascular resistance

Answer 37

increased right ventricular straight --> right ventricular hypertrophy

Question 38

effects of increased left atrial strain

Answer 38

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

Question 39

angioedema occurs due to the accumulation of what substance

Answer 39

bradykinin

Question 40

how does norepinephrine cause an increase in HR

Answer 40

via B1 receptors leading to increased Ca influx

Question 41

JVP in patients with AF would show a decrease in what wave

Answer 41

a wave as this represents abnormal atrial contraction