control of cardiac output Flashcards
what is the maximum capacity of the capillaries?
5l/min
what is the amount of blood cardiac muscle needs to function?
30l/min
how do you calculate cardiac output?
stroke volume X heart rate = cardiac output
what is the extrinsic control of stroke volume?
control of stroke volume by sympathetic inervation
what is the main INTRINSIC method of control of stroke volume?
the frank starling mechanism
what is the frank starling mechanism?
increasing the end diastolic volume, which increases the force of contraction
what happens to tension generated by the heart when you increase end diastolic volume?
you increase the tension generated
what factor means that the aorta has to stretch during systole to accommodate full ventricular stroke volume?
systemic vascular resistance
what causes systemic vascular resistance
the branching of cappilarries and the non-compliance of capillaries
what happens to compliance in arteries with age?
it decreases, so pressure increases with an increase in volume
how do you calculate PULSE PRESSURE?
systolic pressure - diastolic pressure
what is the Mean Arterial Blood Pressure?
diastolic blood pressure + 1/3 pulse pressure
what are two factors which are directly proportional to flow of fluid through a vessel?
- radius of the vessel
- difference in pressure from one end to the other (pressure gradient)
what are two factors which are inversely proportional to the flow through a vessel?
- the length of the vessel
- viscosity
what are two factors which could influence rate of flow but remain relatively constant under normal physiological conditions?
viscosity and length
