Question

How does perspiration leave a cooling effect on our body?
Option
(A) Sweat particles absorb energy from the surrounding to change into vapour thereby reducing the temperature
(B) The particles release energy into the atmosphere and the temperature decreases
(C) The particles absorb energy from the body and converts into vapour thereby increasing the temperature
(D) None of the above

Answer 1

Hint :
Sweating, also known as perspiration, is the secretion of moisture by the sweat glands of mammals' blood. Humans have two kinds of sweat glands: eccrine glands and apocrine glands. The eccrine sweat glands are found all over the body and are in charge of secreting the watery, brackish sweat that is most often caused by high body temperatures. The apocrine sweat glands are found only in the armpits and a few other parts of the body, and they develop an odourless, sticky, invisible secretion that is then odorized by bacteria.

Complete Step By Step Answer:
Sweating is a natural way for the body to control temperature. Sweating is mediated by thermosensitive neurons in the preoptic and anterior regions of the hypothalamus, which are situated in the preoptic and anterior regions of the brain. Inputs from temperature receptors in the skin also affect the hypothalamus's heat-regulating role. In addition to changes in core temperature, high skin temperature lowers the hypothalamic set point for sweating and raises the gain of the hypothalamic feedback mechanism. The sweating response to a raise in hypothalamic ('core') temperature, on the other hand, is much greater than the response to a similar rise in average skin temperature.
Sweating induces evaporative cooling at the skin surface, which lowers core temperature. The skin and superficial vessels cool as high-energy molecules evaporate from the skin, absorbing energy drained from the body. Cooled venous blood then returns to the body's heart, where it helps to keep core temperatures from increasing.
When the atmospheric temperature is higher than the body temperature, heat is transferred through the body rather than out by radiation, conduction, and convection. The only processes left under such conditions are the evaporation of perspiration from the skin and evaporative cooling from exhaled sweat, since there must be a net external heat flow.
Hence option A is correct

Note :
The nerves activate the sweat glands, inducing perspiration, in two situations: during physical heat and during emotional tension. Emotionally induced sweating is mostly limited to the hands, soles, armpits, and sometimes the scalp, while actual heat-induced sweating happens all over the body.