14 terms

The heart (physiology)

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isovolumic contraction (Left ventricle)
Increase in pressure due to contraction, but no change in volume because all valves are closed
EDV
end diastolic volume
ESV
end systolic volume
units for stroke volume
mL/beat
units for cardiac output
ml/min
isovolumic relaxation
Decrease in pressure due to relaxation, but no change in volume because all valves are closed
Stroke volume =
EDV-ESV
Cardiac output =
heart rate x stroke volume
Stroke volume is proportional to the...
FORCE of the ventricular contraction
Force of stroke volume determined by
Length of muscle fibers at the beginning of the contraction and contractility of the heart
Frank-Starling Law
The greater the stretch, the stronger is the heart's contraction. This increased contractility results in an increased volume of blood ejected (Increased SV)
Pre-load
Staring muscle fiber length (this determines how much force can be generated)
After-load
How much pressure is in the aorta because this is the opposing force to contraction
EDV determined by
1. Contraction of veins by skeletal and respiratory pump
2. Time of diastole
3. Peripheral Resistance
4. Constriction of blood vessels
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