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What is meant by high and low pressure in the blood?

for example in my textbook it describes adaptations of the arteries to maintain a high pressure in the blood, but what does it actually mean by a high pressure and what's the importance of this?

Reply 1

macpatgh-Sheldon

Good answer by Ralentas, just to add some other points:

The initial blood pressure generated by the heartbeat (called the systolic blood pressure - normal around 120mm Hg in a young adult) is deendent on the diameter of the so-called resistance arterioles. These vessels have an elastic layer in their walls, which stretches when the heart beats, then rebounds [rather like a pulled rubber band when you let one end go] producing a second smaller peak in blood pressure called diastolic blood pressure (normal about 80 mm Hg).

The human body has several mechanisms of controlling and maintaining blood pressure, including control of sodium levels by the kidneys (you might know that doctors recommend people with high blood pressure to limit salt intake) as well as various chemicals, some working via nerves, that can change the diameter of arterioles, thus modulating the resistance posed against blood flow and controlling blood pressure.

M (ex-medic)