Overview of the function of the cardiovascular system Flashcards
Function of the CVS
- Bulk flow system: O2 and CO2, nutrients, metabolites, hormones, heat.
- Is amazingly reliable: over 2.5 billion beats in 70 years.
- Is remarkable flexible: pump can vary output, vessels can redirect blood, vessels can store blood.
How are pumps arranged in the CVS?
Pumps are in series
- Therefore output must be equal
How are most vascular beds arranged in the CVS?
Most vascuar beds are in parallel. Therefore - All tissues get oxygenated blood - Allows regional redirection of blood - Exceptions prove the rule
What is the cardiac output and oxygen consumption in the heart at rest?
Cardiac output = 4%
Oxygen consumption = 10%
What is the flow at rest of blood in the heart?
215 ml/min
What is the overall resting cardiac output?
5000 ml/min
What is the pressure difference equal to?
Pressure difference = mean arterial pressure - central venous pressure
-Affects all tissues
How is flow calculated (equation)?
Change in pressure/Resistance
- Controlled by radius^4
- Selectively redirects flow
What structures act as “the taps” controlling resistance (and flow) to each vascular bed?
Arterioles
Features of the Aorta
Elastic arteries = aorta
- wide lumen, elastic wall
- damp pressure variations
Features of arteries
Muscular arteries = other arteries
- wide lumen, strong non-elastic wall
- low resistance conduit
Features of arterioles
Resistance vessels = arterioles
- narrow lumen, thick contractile wall
- control resistance & therefore flow
- allow regional redirection of blood
Features of capillaries
Exchange vessels = capillaries
- narrow lumen, thin wall
Features of venules and veins
Capacitance vessels = venules & veins
- wide lumen, distensible wall
- low resistance conduit, & reservoir
- Allows fractional distribution of blood between veins & rest of circulation (esp. heart)
