What is the purpose of goose bumps?
Sends more nerve impulses to blood vessels in the skin that cause the vessels to narrow, which restricts blood flow to the skin, reducing heat loss.
Stimulates the skeletal muscles, causing brief bursts of muscular contraction, known as shivering, which generates heat.
When the core temperature rises above its set point, the hypothalamus:
Sends fewer nerve impulses to blood vessels in the skin, causing them to dilate, which increases blood flow to the skin and promotes heat loss.
Activates the sweat glands, and when sweat evaporates off the skin surface it carries a large amount of body heat with it.
The puckering of the skin that takes place when goose-flesh is formed is the result of the contraction of the muscle fibers in the skin. This muscular activity will produce more heat and raises the temperature of the body.