The following statements are made about body temperature regulation in humans:
A. Lactic acid and potassium ions are less concentrated in sweat while sweating little than while sweating a lot.
B. When the temperature of the surroundings becomes greater than that of the skin, body loses heat by conduction.
C. When heat is applied directly to the pre-optic area of hypothalamus by inserting a thermode in the brain, the animal begins to sweat profusely.
D. Chemical thermogenesis through thyroid gland stimulation requires weeks of exposure to cold temperature.
Which one of the following options represents the combination of all correct statements?

Correct option is A

Correct Answer:
(a) C and D
Explanation:
The pre-optic area of the hypothalamus functions as the primary thermoregulatory center, and direct heating of this region triggers strong heat-loss responses such as profuse sweating (C).
Chemical thermogenesis mediated by thyroid hormones is a long-term adaptive response and typically requires weeks of cold exposure to become effective (D).
Information Booster :
· The hypothalamus integrates peripheral and central thermal inputs.
· Sweating and vasodilation are rapid heat-loss mechanisms.
· Thyroid-dependent thermogenesis increases basal metabolic rate slowly.
· Short-term cold responses rely more on shivering than hormones.
Additional Information (Incorrect Options):
Statement A: Incorrect—during low sweating rates, solute reabsorption is higher, making sweat more, not less, concentrated.
Statement B: Incorrect—when the environment is hotter than the skin, the body gains heat by conduction rather than losing it.
Hence, options including A or B are incorrect.