Mechanisms that cool and rise the body temperature - Thermoregulation

Humans are warm blooded animals, and this feature enables us to survive in any region of the world. Thermoregulation helps us in maintaining our body temperature. Body temperature of an average person falls in a narrow window between 98°F (37°C) and 100°F (37.8°C). If your body temperature falls below 95°F (35°C) then it is called "hypothermia", which is a life threatening condition. If body temperature rises above 107.6°F (42 °C) then it can cause brain damage or even death.

What causes body temperature to rise or fall ?

Body temperature may rise due to fever, exercise and digestion. It can fall due to drug use, alcohol use or metabolic conditions. One of the most common metabolic condition which causes fall in body temperature is under-functioning thyroid gland.

Which part of brain controls body temperature?

Hypothalamus (a section of your brain) controls body temperature through thermoregulation. As soon as it senses that temperature is rising or getting low, it starts sending signals to muscles, organs, glands, and nervous system to get the body temperature back on track.

Our thermoregulation works in two ways, either rising the body temperature or lowering the temperature, depending on the need.

How thermoregulation cools the body?

If your body temperature is high then thermoregulation starts the following mechanisms in the body.

  • Sweating is the simplest and very first step that our body takes to cool itself. Sweat glands release sweat, in order to be evaporated to cool the skin. It mostly happens when you exercise or when you are in hot environment.
  • Vasodilatation is totally internal process that you can't notice. In vasodilatation the blood vessels that pass just under your skin get wider, so that blood flow increases towards to skin, where it radiates the heat to the air that is touching your skin.

How thermoregulation rises the body temperature?

If your body temperature is getting low then thermoregulation starts the following mechanisms in the body.

  • Shivering produces by heat by shaking muscles inside the body. It is a type of thermogenesis, processes that increase body temperature.
  • Vasoconstriction restricts the blood supply near the skin by constricting the blood vessels and making them narrow. It retains the heat inside the body and stops further cooling down of internal body temperature. Vasoconstriction is just reverse of vasodilatation.
  • Thyroid gland increases our metabolism by releasing some hormones. Rise in metabolism increases cellular respiration which generates internal heat and it rises overall body temperature. It is a type of hormonal thermogenesis.
  • Erector muscles in the base of body hairs contract to make hairs stand, which is also known as goosebumps. It traps heat by trapping the warm air next to skin.
  • Fat under the skin act as an insulation which helps in trapping the heat, especially during the winters.

Ageing and Thermoregulation

As a person grows old the ability to regulate body temperature don't remain as efficient as a young person. It happens due to following reasons.

  • Amount of fat under the skin usually decreases with age. Fat is a bad conductor of heat and it stops body heat from radiating outside. Lack of fat under the skin makes older people more dependent on woolen clothes.
  • Ability to sweat decreases with old age. It puts old age people at the risk of heat stroke.
  • Fever is an internal mechanism of body to protect itself from those infections which can be terminated by body heat. But body's ability to rise the temperature also decreases with age. It puts old age people at risk of low fever for longer duration, which might be sign of some infection.  

Interesting facts about Human Body Temperature

  • Body temperature of a healthy human fluctuates by 0.5 °C (0.9 °F) everyday.
  • Body temperature is sensitive to various hormones. Women face more hormonal changes due to menstrual cycle and thus their body temperature varies more than men.

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