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Communication systems

The human body has two communication systems that allow us to respond to any changes in our environment.

The nervous system uses nerve impulses (electrical impulses) to react quickly to a .

The hormonal system uses to react slowly to a stimulus.

Nervous systemHormonal system
SpeedFastSlow
Nature of responseElectrical impulsesHormones/chemicals that travel in blood
Speed
Nervous systemFast
Hormonal systemSlow
Nature of response
Nervous systemElectrical impulses
Hormonal systemHormones/chemicals that travel in blood

The nervous system

The brain and form the central nervous system (CNS). The CNS controls and coordinates responses between and .

Diagram of the human central nervous system with the brain and spinal cord labelled
  • Stimuli are changes in our environment that we respond to and are detected by receptors.
  • Different receptors are sensitive to different stimuli (e.g. receptors in the eye are sensitive to light).
  • The sensory neurone carries information in the form of nerve impulses from the receptor to the .
  • The coordinator – brain or spinal cord – determines whether or not to respond to the stimulus. The association neurone is found here.
  • The motor neurone carries information from the coordinator to an effector.
  • An effector is a muscle or gland that can bring about a response.
  • The sensory neurone is connected to the association neurone by a synapse.
  • The association neurone is connected to the motor neurone by a synapse.
Diagram summarising how information flows from receptors to effectors in the nervous system.

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