Overview of the Function of the Cardiovascular System Flashcards
The cardiovascular system is a bulk flow system which transports;
O2 and CO2
Nutrients – picked up mainly in the gut and stored in the liver
Metabolites
Hormones
Heat – produced at the core, sent to the periphery
What is the equation that relates flow, pressure and resistance through any vessel?
Flow = pressure difference/resistance
How can you calculate the pressure difference from central venous pressure and mean arterial pressure?
Pressure difference = MAP - CVP
What controls the resistance?
Vessel radius ^4
How to arterioles affect resistance and flow?
Arterioles control resistance and therefore flow to each vascular bed
What is the difference between pressures in the left and right heart?
In the left heart there is high pressure MAP, while in the right heart there is low pressure CVP
How do the pumps of the CVS vary from most other vascular beds?
Pumps of CVS are in series, while most vascular beds are in parallel
What are the advantages of pumps being in parallel?
All tissues get oxygenated blood
Allows regional redirection of blood
Why must the output of the CVS pumps be equal?
If one side pumped more than the other, blood would accumulate - in the lungs if right side pumped more, or in the periphery if left side pumped more
What are the other vascular beds that lie in series rather than parallel?
Those between hypothalamus and pituitary, and those between gut and liver
With what does cardiac output roughly correspond? What are the exceptions to this?
Oxygen consumption
Kidneys and skin are the exceptions - they have less oxygen consumption than cardiac output
Heart is also an exception as oxygen consumption exceeds cardiac output
What is the basic structure of elastic arteries?
Wide lumen and elastic wall
What is the function of elastic arteries?
Dampens pressure variations by absorbing energy using contraction phase and releasing stored energy on relaxation
What is the only elastic artery?
The aorta
What is the basic structure of muscular arteries?
Wide lumen, strong non-elastic wall
