In the weather

Let's just say that when people are nervous, they will secrete a lot of adrenaline, which can make the blood vessels on the surface of skin and mucous membrane contract, so that the blood supply of people's limbs will decrease rapidly, and the skin without blood supply will become cold.

However, under stress, people's metabolism is more vigorous than usual, producing more heat, so when the weather is hot, after the stress, the blood supply returns to normal, and more heat is transported to the skin, and people feel hot.

Muscle contraction requires a certain intensity of stimulation, which we call the threshold (assumed to be 10). Hand and foot tremble because the muscles of the hand are highly excited in a tense state, and the threshold drops (assumed to be 5). Therefore, in general, stimulation with an intensity of 8 (less than 10) is not enough to make the muscles contract, while the intensity in a tense state is 8 (greater than 5).