BSCC Physiology 016
In the video example of a systolic BP of 120mmHg and a Diastolic of 80mmHg
- Pressure falls very slightly in large and medium sized arteries because resistance to flow is small
- Pressure falls rapidly in smaller arteries and arterioles due to the total cross sectional area of vessels . However, it is important to remember that the small arteries and arterioles provide the main site of peripheral resistance against which the heart pumps (dependent on the amount of constriction or dilatation – also called Relative resistance, highest in aterioles)
- Mean pressure at end of arterioles is 30-38mmHg
TA = Total cross sectional area of vessels (maximal in capillaries and venules – about 10x that in arterioles)
If you exclude the cross sectional area of the capillaries you will not on the left (the arterial side) the cross sectional area is small as compared to the right (the venous side). This shows diagrammatically, the capacity that the venous system has over the arterial system to pool blood.