Control of Body Temperature (AQA GCSE Biology)

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Monitoring of Body Temperature

  • The human body needs to maintain a temperature at which enzymes work best, around 37°C
  • Processes such as respiration release energy as heat; and the body loses heat energy to its surroundings – the energy gained and lost must be regulated to maintain a constant core body temperature
  • Body temperature is monitored and controlled by the thermoregulatory centre in the brain
  • The thermoregulatory centre contains receptors sensitive to the temperature of the blood
  • The skin contains temperature receptors and sends nervous impulses to the thermoregulatory centre

A cross-section of human skin, IGCSE & GCSE Biology revision notes

Human skin contains structures involved in processes that can increase or reduce heat loss to the surroundings

Controlling Body Temperature

  • If the body temperature is too high, blood vessels dilate (vasodilation) and sweat is produced from the sweat glands
  • Both these mechanisms cause a transfer of energy from the skin to the environment, cooling the body down

 Responses in the skin when hot, IGCSE & GCSE Biology revision notes

Responses in the skin when the body temperature is too high and needs to decrease

  • If the body temperature is too low, blood vessels constrict (vasoconstriction), sweating stops and skeletal muscles contract (shiver)
  • These mechanisms reduce heat loss to the surroundings (with skeletal muscle contraction increasing heat released in the body)

 Responses in skin when cold, IGCSE & GCSE Biology revision notes

Responses in the skin when body temperature is too low and needs to increase

Examples of Body Temperature Control

Higher tier only

  • The mechanisms described above lower or raise body temperature
  • In the exam, you may be given examples of different contexts in which the body temperature needs to decrease (when someone is too hot) or increase (when someone is too cold)
  • Learn the following concepts to ensure you can suggest what changes are happening and why:

Body temperature regulation summary table

Body temperature too high Body temperature too low
  • Sweat is secreted by sweat glands in the skin
  • Sweat evaporates, cooling the skin
  • Heat energy from the body is lost as liquid water in sweat becomes water vapour (a state change)
  • Skeletal muscles contract rapidly and shivering occurs
  • Skeletal muscle contraction is involuntary and requires energy from respiration (which releases heat energy)
  • Blood vessels close to the skin get wider (dilate)
  • This allows excess heat to radiate from the blood into the environment
  • This is called vasodilation
  • Blood vessels close to the skin get narrower (constrict)
  • This reduces heat loss from the blood into the environment
  • This is called vasoconstriction

Regulating body temperature, IGCSE & GCSE Biology revision notes

Remember homeostasis involves the maintenance of constant internal environment; temperature control is an example of negative feedback

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Lára

Author: Lára

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.