Flashcards in The Peripheral Circulation Deck (92)
What are the main components of the CVS?
Heart, Arteries, Arterioles, Capillaries, Veins
What is the function of the heart?
Cyclic muscular pump that enables circulation of the blood
What is the function of arteries?
Gross conduction and distribution of blood supply
What is the purpose of arterioles?
Local distribution and fine control of defined tissue volume
What is the function of capillaries?
Microdiffusion and filteration
What is the function of veins?
Collection and return, and capacitance
What is compliance?
Ability to distend and increase volume due to pressure increase
What is capacitance?
Effectively the same as compliance- a measure of relative volume increase per unit in pressure
What is pressure?
A measure of mechanical energy gradient in blood that drives flow around different parts of the system
What does cyclic muscular contraction produce?
Pressure waves to move blood into circulation
How is cardiac output calculated?
Stroke volume x heart rate
What is the average cardiac output?
What happens with each beat of the heart?
Stroke volume is delivered to the major arterial tree
What is the resistance of the major arterial tree?
What is the compliance of the major arterial tree?
~1-2% change / mmHg
Still very important
What is the pressure of the major arterial tree?
What needs to be true of arterial pressures?
They need to be high enough to drive cardiac output through high resistance arterioles
How much can resistance very from arteriole to arteriole?
What is total peripheral resistance?
The sum of all arteriolar resistance
What does compliance affect?
Pulsatile pressure flow in arteries
In what manner does the heart eject blood?
When does blood flow into arteries?
What does compliance act to do?
Store mechanical energy of rising pressure wave during systole, and so dissipates energy more gradually over diastole
What would happen if arteries were very rigid walled?
Pressure would rise enough in systole to force whole stroke volume through TPR, but fall to 0 in diastole
What effect does aortic compliance have?
Dampens the pulsatile nature of the systolic pressure wave
Which vessels act to smooth out the pressure wave during systole?
Aorta and elastic arteries and less smooth muscle
What is the Windkessel Effect?
The capacitance effect, whereby more blood flows in than out, so pressure doesn’t rise as rapidly because elastic arteries recoil in diastole to release energy, which smooths flow through arterioles
What is systolic pressure?
The maximum arterial pressure that is reached during systole
What is diastolic pressure?
The minimum arterial pressure that is reached during diastole