Question

Explain the terms "vasodilation" and "vasoconstriction". How do these processes contribute in the regulation of the body temperature? <!--td {border: 1px solid #cccccc;}br {mso-data-placement:same-cell;}--> [Review Questions - Pg No.134 - LAQ - 2]

Answer 1

Vasodilation: When the temperature of the surroundings is high or the body temperature is increased due to excessive physical activities, there is an increased supply of blood to the skin and the blood vessels are dilated. This is called vasodilation.

Vasoconstriction: When the temperature of the surroundings is low, there is a decrease in the supply of blood to the skin and the blood vessels are narrowed. This is called vasoconstriction.

These processes contribute in the regulation of the body temperature in the following ways:

• When the temperature high, blood vessels dilate that increases the supply of blood to the skin. This increased blood supply causes more sweating and high heat is lost by conduction, convection and radiation. Thus, the body temperature is maintained in hot weather.

• When the temperature low, blood vessels become narrow that decreases the supply of blood to the skin. This decreased blood supply causes less sweating and less heat is lost by conduction, convection and radiation. Thus, the body temperature is maintained in cold weather.