Edexcel IGCSE Biology 复习笔记 2.10.2 Control of Homeostasis

• Homeostasis (maintaining controlled conditions within the body) is under involuntary (automatic) control
• This means that the brain stem (or non-conscious part of the brain) and the spinal cord are involved in maintaining homeostasis – you don’t consciously maintain your body temperature or blood glucose level
• These automatic control systems may involve nervous responses or chemical responses (e.g. via hormones)
• All control systems that carry out co-ordinated responses require the following:
  • A stimulus (a change in the environment e.g. a change in glucose levels in the blood, a change in body temperature etc.)
  • A receptor (receptor cells that detect stimuli)
  • A coordination centre (such as the brain, spinal cord and pancreas), which receives and processes information from receptors
  • An effector (a muscle or gland), which brings about responses to restore optimum levels

   

A co-ordinated response (such as that required when there is not enough water in the blood) requires a stimulus, a receptor and an effector

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