Question

When looking at the extrinsic control of the arterioles, explain how sympathetic stimulation (stress) affects the blood flow and diameter of vessels in the heart vs circulatory system when comparing alpha-1 receptors and beta-2 adrenergic receptors. What are the corresponding ligands (hint…abcd)?

Answer 1

Stimulation of alpha 1 receptors leads to vasoconstriction by contraction of smooth muscles in the blood vessels.

Stimulation of beta 2 receptors leads to vasodilation by relaxation of smooth muscles in the blood vessels.

So the net response depends on which ever receptors are in larger numbers.

For example in skin where alpha 1 receptors are more in number there will be vasoconstriction

Whereas in skeletal muscles where there are more number of beta 2 receptors there will be vasodilation.

Phenylephrine,oxymetaxoline are ligands at alpha 1 receptors and epinephrine and ephidrine are ligands at beta 2 receptors