Homeostasis

Learn about homeostasis.

This lesson includes:

  • one video on the principles of homeostasis
  • two activities to reinforce learning

Learn

What is homeostasis?

Homeostasis is the regulation of internal conditions inside cells or organisms, to create the optimum conditions for biological function.

The main homeostatic processes in the body are:

  • controlling body temperature
  • maintaining optimal water levels in cells
  • balancing blood sugar levels

In this video, Greg Foot introduces the principle of homeostasis and looks at how it is used to regulate water levels in cells.

How is homeostasis controlled?

The nervous system and hormones use both nervous and chemical responses respectively to control and regulate homeostasis in the body.

The main parts of this 'control system' include:

  • receptors detect a stimulus, which is a change in the environment, such as temperature change
  • coordination centres in the brain, spinal cord and pancreas. They receive information from the receptors, process the information and instigate a response
  • effectors, such as muscles or glands create the response. Glands often release a hormone, which would restore the optimum condition again

Controlling body temperature

Maintaining the optimal body temperature (37°C) is controlled by the thermoregulatory centre. It is contained within the hypothalamus in our brains.

When we are hot:

  • vasodilation opens up our blood vessels, meaning more heat is lost through the skin
  • sweating occurs and heat is transferred out through drops of sweat

When we are cold:

  • vasoconstriction narrows our blood vessels so less heat is lost through the skin
  • shivering occurs in the muscles, generating more heat in the body

Vasoconstriction occurs when we are too cold.

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Maintaining blood sugar (glucose) levels

If sugar levels get too high:

  • the pancreas secretes the hormone insulin
  • insulin promotes the storage of excess glucose as glycogen

If sugar levels get too low:

  • the pancreas secretes the hormone glucagon
  • glucagon breaks down glycogen into glucose

Diabetes is a disease that occurs in people who cannot produce enough insulin to break down the amount of glucose in their body.

Practise

Practise

There are lots of ways to try out your science skills.

Activity 1

Fill in the homeostatic cycle for controlling body temperature with this downloadable worksheet from Beyond.

Controlling body temperature

Activity 2

Fill in the homeostatic cycle for controlling water levels in the body with this downloadable worksheet from Beyond.

Controlling water levels
GCSE Biology
14 - 16 Biology
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