Cardiovascular physiology and action potentials Flashcards

1
Q

Describe what happens during the 5 phases of the cardiac action potential

A

Phase
0 Rapid Na influx (depolarisation)
1 Efflux of potassium (Early repolarisation)
2 Slow influx of calcium (Plateau)
3 Efflux of potassium (Final repolarisation)
4 Resting potential is restored by Na+/K+ ATPase

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2
Q

How is a new cardiac action potential created?

A

slow entry of Na+ into the cell decreasing the potential difference until the threshold potential is reached, triggering a new action potential

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3
Q

Where in the heart is conduction velocity fastest?

A

Ventricular conduction Purkinje fibres (2-4 m/sec)

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4
Q

Where is conduction slowest in the heart?

A

AV node

Atrial conduction 1 m/sec
AV conduction 0.05 m/sec
Ventricular conduction Purkinje fibres (2-4 m/sec)

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5
Q

How is the Left ventricular ejection fraction calculated?

A

LVEF = (stroke volume / end diastolic LV volume ) * 100%

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6
Q

end diastolic LV volume - end systolic LV volume = ?

A

Stroke volume

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7
Q

stroke volume x heart rate =?

A

cardiac output

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8
Q

Systolic Pressure - Diastolic Pressure =?

A

pulse pressure

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9
Q

Factors which increase Pulse Pressure

A

a less compliant aorta (advancing age)
increased stroke volume

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10
Q

mean arterial pressure / cardiac output = ?

A

Systemic vascular resistance

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11
Q
A
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