Question

Sudorific glands are characteristic feature of
A) Birds
B) Mammals
C) Poisonous snakes
D) Toad

Answer 1

Hint: The animals of this group are endothermic, dependent on or capable of the internal generation of heat and they have hair on their body.

Complete Answer:
Snakes and toads are ectothermic (cold-blooded) animals. They are unable to regulate their body temperature internally. To maintain their body temperature they are completely dependent on the external sources.
1) Birds and mammals are endothermic (warm-blooded) animals.
- The birds use different physiological and behavioural traits to maintain their body temperature i.e. thermoregulation.
- In cold conditions some birds reduce their body surface area and thus reduce heat loss by tucking their head in the body feathers and fluffing their feathers to trap heat.

2) In mammals, sudorific glands play a vital role in regulation of body temperature.
- Sudorific glands are also known as sweat glands, which are exclusively found in mammals. Sweat glands are coiled tube-like structures that produce sweat. These glands are exocrine glands.
- The main function of sweat is to regulate the body temperature (thermoregulation) by cooling the skin surface. It also helps in the removal of some of the wastes like urea and lactic acid.

3) There are three different types of sweat glands – eccrine, apocrine, and apocrine. These glands remain present in the dermis, the middle layer of skin. They consist of a central lumen and secretory cells.

(A) Eccrine glands are distributed almost everywhere on the skin. The eccrine glands open on the skin surface directly.
- Their primary functions are thermoregulation, excretion and protection. The sweat released by eccrine glands is mostly water but also contains electrolytes like sodium and potassium ions.
- These glands respond by discharging sweat on rising of body temperature due to physical activity or fever or other reasons. This sweat is then evaporated from the surface of the skin that efficiently cools down body temperature.

(B) Apocrine glands although present from birth but become active only after puberty. Distribution of Apocrine glands is restricted to the armpits, eyelids, mammary glands, anal, and genital areas.
- Unlike the eccrine glands, apocrine glands open in the pilary canal of the associated hair follicles. The substance they secrete is oily in nature containing lipids, proteins, and steroids that provides nutrients for bacteria to grow on the skin.
- These bacteria are responsible for a distinctive body odour. The apocrine sweat also contains pheromone like substance. Rather than temperature regulation, apocrine glands become active in response to anxiety, fear and sexual excitement.

(C) Apocrine glands have the features of both eccrine as well as apocrine glands. These glands are found at the same locations of apocrine glands but they secrete watery sweat that is similar to eccrine glands.

Thus, the correct answer is B, i.e., Mammals.

Note: Eccrine sweat glands are known as true sweat glands as their main function is to control the body temperature.