The process of decrease in any vessel diameter that occurs due to smooth muscle contraction is called:

a. vasodilation.

b. venodilation.

c. vasoconstriction.

d. venoconstriction.

e. None of the answers is correct.

c. vasoconstriction

Explanation:

Vasoconstriction is a process which involves the narrowing or tightening of blood vessels which becomes smaller when the smooth muscles of these vessels become contracted. The tightening or narrowing of the blood vessels results in an increase in resistance as blood pressure rises, which leads to the restriction of blood flow. Vasoconstriction is the opposite of vasodilation.

c. vasoconstriction

Explanation:

In condition of excess blood loss (haemorrhage) or exposure to very cold temperature, or drop in blood pressure, the process by which the smooth muscle cells of the walls of the artery and arteriole contract to increase the resistance of the vessels to reduce blood flow is called vasoconstriction.

The mechanisms, involve Increase stimuli from epinephrine and sympathetic nervous system which leads to increase in influx of Ca + ions into the saccolemma reticulum of the smooth muscle cells.

Calcium-modulated - protein in the saccolema binds with Calcium. This results in a signal pathways, of calcium binding with tropin, tropomyosin exposure of myosin-binding sites, and formation of cross-bridges for sacomere shortening leading to contraction of smooth muscles for the narrowing of blood vessels.

Certain drugs called vasoconstrictors can also cause vasoconstriction of blood vessels. They are drugs prescribed for elevation of blood pressure.