Question

Which response to overcooling does not involve muscle contraction?
A. Blood vessels narrowing
B. Hairs standing up
C. Shivering
D. Reduced sweating

Answer 1

Hint: Temperature is an important environmental factor that affects the enzyme kinetic, basal metabolic activities and the physiological functions of the organisms.

Complete answer: Humans are homoeothermic animals i.e. they maintain a constant body temperature of 37 degrees centigrade.
Shivering is an involuntary movement that involves the tightening and relaxation of muscles in rapid succession. It is a natural response of the body to low temperatures that helps in warming up. The nerve impulse for this is sent by hypothalamus to the brain. Shivering generates heat that helps in raising the body temperature.
When exposed to cold temperatures, the arteries of fingers go into vasospasm. This narrows the blood vessels and temporarily limits the blood supply to the fingers. The vasoconstriction helps to minimize the loss of heat from the warm blood and helps in maintaining a constant internal temperature.
Whenever we feel cold the muscles on our body contract which causes a shallow depression on the surface of the skin that makes the hair protrude or raise.
Sweating is a response of the body to high temperatures. It is also called perspiration and it involves the release of salt-based fluid from the sweat glands of the body. Sweating can occur due to many reasons like emotional state of the body, eating spicy food, fear, nervousness, anxiety, etc.
So there is a narrowing of blood vessels i.e. vasoconstriction, hair standing up, shivering but no reduced sweating.

Note: The automatic process to maintain a constant internal environment is called homeostasis and the mechanisms designed to accomplish this task are known as the homeostatic mechanisms.