Overview of the Function of the CV system Flashcards
What are the functions of the CV system?
Bulk flow system:
- O2 and CO2
- Nutrients
- Metabolites
- Hormones
- Heat
Why is the CV system regarded as being flexible?
- It can vary pump output
- The vessels can redirect blood
- The vessels can store blood
Why must output be from the right and left side of the heart be equal?
They are in series
What is the importance of the right and left sides of the heart being in series?
If the weren’t then output would not be equal and there would be an accumulation of blood
How are most vascular beds organised?
In parallel
What does vascular beds in parallel allow?
- All tissues get oxygenated blood
- Allows regional redirection of blood
What are 2 examples of vascular beds that lie in series?
- Hypothalamus and pituitary gland
- Gut and liver
What is usually the relationship between oxygen consumption and cardiac output at rest/
The usually correlate so percentages are very close
Why does skin have a high cardiac output?
It is involved in thermoregulation
What is the pressure difference equal to?
Mean arterial pressure- central venous pressure
What is flow equal to?
Pressure difference divided by the resistance
What is resistance controlled by?
Radius of vessels
What do the arterioles do?
They act as taps as the control the resistance and flow to each vascular bed.
What is the order of the vessels that blood flows through upon leaving the heart?
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
What is an example of an elastic artery?
Aorta
What are the characteristics of elastic arteries?
- Wide lumen
- Elastic wall
- Damp pressure variations
What are the characteristics of muscular arteries?
- Wide lumen
- Strong non-elastic wall
- Low resistant conduit
Which vessels are referred to as the resistance vessels?
Arterioles
What are the characteristics of the resistance vessels?
- Narrow lumen
- Thick contractile wall
- Control resistance and therefore flow
- Allow regional redirection of blood
What vessels are known as the exchange vessels?
Capillaries
What are the characteristics of the exchange vessels?
- Narrow lumen
- Thin wall
What vessels are known as the capacitance vessels?
- Venules
- Veins
What are the characteristics of the capacitance vessels?
- Wide lumen
- Distensible wall
- Low resistance conduit and reservoir
- Allows fractional distribution of blood between veins and rest of circulation
What enhances the diffusion ability of capillaries?
Their large surface area to volume ratio
