ABSTRACT
Blood pressure, the pressure exerted on vessel walls, is affected by flow and resistance. Flow is created by the stroke volume and the viscosity of blood.
The force of arterial blood flow decreases slightly as the distance from the heart increases, but this decrease is usually more than offset by increased resistance. Resistance is the sum of the arterial wall tone (e.g. increased with atherosclerosis, decreased with dilatation), the vessel size, and the pressure from tissues (e.g. oedema).
