2 CVS Control of Cardiac output Flashcards
What is cardiac output?
The amount of blood pumped per minute?
What is Afterload?
Afterloadis the pressure against which the heart must work to eject blood during systole(roughly equivalent to aortic pressure)
What is Preload?
Amount the ventricles are stretched/filled in diastole – related to the end diastolic volume or central venous pressure
What is total peripheral resistance?
Sometimes referred to as systemic vascular resistance - resistance to blood flow offered by all the systemic vasculature – great majority of resistance happens at the arterioles
If TPR falls and CO us unchanged?
Arterial pressure will fall
Venous pressure will increase
If CO increases and TPR stays the same?
Arterial pressure will increase and venous pressure will fall
What is stroke volume?
End diastolic volume - end systolic volume
Why is stroke volume dependent on?
Afterload, preload, contractility
The higher the venous pressure?
The more the heart fills
What is the frank stirling law?
The more the heart fills , the harder it will contract, the harder it contracts the bigger the stroke volume
What is the ideal sarcomere length?
2.2um
What extrinsic factors have an effect on contractility?
sympathetic stimulation
