When it’s too hot or cold, skin and hair play important roles in keeping the temperature at a safe and comfortable level. A thermostat in the brain’s hypothalamus monitors signals from the body’s sensors. It then sends signals for the body to act to cool itself down or stay warm.
Sweating
Sweat cools the skin as it evaporates.
Keeping cool
If the temperature rises above 38ºC (100.4ºF), sweat glands produce watery sweat to cool the skin. Blood vessels at the skin’s surface widen, so heat can escape easily. Hair relaxes, so heat is released into the air.
Keeping warm
When the temperature drops, skin goes into heat-retention made. Blood vessels become narrower to prevent heat loss from the warm body. Muscles contract to make the skin’s hairs stand upright to trap warm air. These muscles pull on the skin above, making lumps known as goosebumps.
Picture Credit : Google