Final answer:
Shivering is an automatic and involuntary response caused by a drop in body temperature, aiming to restore homeostasis. It can occur during cold exposure to generate heat or during a fever as the body attempts to fight infection. The process is not highly efficient and is part of the body's emergency heat-generating mechanisms.
Step-by-step explanation:
Shivering is an involuntary response that can occur due to coldenvness, fever, or a neurological condition. In the context of cold exposure, shivering is initiated when the hypothalamus in the brain detects a temperature drop below the body's set point. Nerves from the somatic nervous system stimulate skeletal muscles to contract and extend, releasing heat energy to raise body temperature and maintain homeostasis.
However, shivering can also happen during a fever, where the body's temperature set point is increased by the hypothalamus as a response to infection, leading to muscle contractions even though the body temperature is already high. This physiological response integrates the immune system with the nervous system to help fight off pathogens.
The efficiency of the body when shivering is not particularly high, as it is a form of emergency heat production. When energy reserves are depleted, and core temperature drops, it can lead to severe consequences like confusion, loss of consciousness, or frostbite. The body also has non-shivering mechanisms, such as metabolizing fat tissue for heat, to respond to cold. In extreme cases of cold, actions such as running can temporarily prevent shivering and may help preserve extremities from freezing, though at the risk of more severe systemic body cooling over time.