Question

In which direction is the smooth muscle oriented: longitudinally (down the length of the blood vessels) or circumferentially (around the circumference of the blood vessel)? Explain how this orientation allows for blood vessels to contract and expand.

Answer 1

The smoot muscle is oriented circumferentially (around the circumference of a blood vessel).

When the smooth muscle contracts, it narrows the whole diameter of the vessel. This is known as vasoconstriction and during this less blood flows through the vessel.

When vasodilation occurs, the muscle cells relax and the diameter of the vessel dilates (expands) allowing more blood to go through.

Hope this helps! This is my favorite subject because I am in the Pre-Med magnet in 12th grade! :)

Answer 2

It is known that the smooth muscles are present along the blood vessel's circumference. Thus, because of this alignment when the contraction of smooth muscles takes place, the diameter of the blood vessels also constricts. As a consequence, less concentration of blood will move inward. This is called vasoconstriction of blood vessel. On the other hand, the relaxed state of muscle leads to dilation of blood vessel. This is known as vasodilation and due to this more blood will flow in the blood vessel.