Question

what affect does vessel damage have on arterioles? (autoregulation of arterioles)

Answer 1

Autoregulation of arterioles

In any tissue of the body, an acute increase in arterial pressure (which can result in vessel damage) will cause an immediate increase in blood flow. However with autoregulation - a acute type of control, within >1min the blood flow returns back to normal. there are two theories of autoregulation:-

1) Metabolic theory

When arterial pressure increases the blood flow to the tissue increases. As a result the oxygen and nutrient supply to the tissue increases, which in turn causes vasoconstriction of the blood vessels supplying the tissue. Hence the blood flow returns to normal despite an increase in arterial blood pressure.

2) Myogenic Theory / Bayliss Theory

INcrease in arterial blood pressure will stretch the wall of small blood vessels. Stretch allows increased movement of Ca2+ from the extracellular fluid into vascular smooth muscle cells due to the opening of Ca2+ channels. This causes the vascular smooth muscles to contract. This prevents overstretching of Blood vessels. this will thus prevent increase in blood flow despite an increase in arterial blood pressure.