Our body has to maintain a core temperature of around 98.6°F (36.9°C) and our brain carefully monitors this temperature so that the consequences of chilled core or hypothermia are prevented. If at all the skin surface becomes too cold, signals are sent to the brain by the skin receptors due to which the body starts its warming function. In shivering our body muscles expand and contract in high speed. During shivering our limbs become quaky and even jaw muscles shiver making the teeth chatter.
Shivers are nothing but body reflexes which our body performs automatically so as to keep us safe and healthy. These reflexes are monitored and controlled by our brain or nervous system, spinal cord along with numerous tiny nerves that are spanned out all our body. Nerves are small wires or strings that are designed to transmit information. So, what information do these nerves pass on? Your bodies nerves sense when the lake’s chilled water starts making you cold and brings the body temperature lower than the normal; it sends the signals that the body is not safe and need to be warmed up.
The signals transmitted by the nerves reach the brain and also the spinal cord and tells you to take a towel and wrap around your body. The next thing that happens is tightening and loosening of muscles in bursting speed. This is a way of body to make you warmer. Once you are warm enough shivering stops. Apart from shivering due to cold we also shiver when we get excited or are afraid of something. When such feelings arise in your mind, the brain along with the nerves transmit message to all the nerves of the body making you shiver.
Whenever you shiver tiny bumps are formed all over the surface of your skin. These are the Goosebumps and are formed because of the presence of hair on skin. When the contraction and expansion of muscles occur during shivering the hair attached to the skin become tight and are thrown upwards towards the air. These are called Goosebumps because they resemble a goose or chicken.
Anesthesia is administered to a person to make him unconscious during surgery. But sometimes it can disturb the ability of our body to regulate body temperature. After the surgery, hence many times the core body temperature drops and the patient shivers till the body comes back to its normal temperature.
We become feverish when our body’s immune system responds to the infection. The high temperature triggers off the hypothalamus of our brain and causes the body to heat. Due to this the microbes are impaired and our immune system can work more effectively. During fever since our body temperature is reset by the hypothalamus the core temperature is more than the normal temperature. So as to maintain this high temperature the body starts shivering.