1. Key Terms in Coordination

  • Coordination: linking together the physiological activities of body organs/systems in time and space for efficient functioning.
  • Irritability: the ability of living organisms to detect and respond to changes in their environment.
  • Stimulus: any change in the internal/external environment that causes a response.
  • Receptor: cells specialised in detecting stimuli and sending messages to the brain.
  • Effector: a gland or muscle that carries out instructions from the brain.
  • Neuron: the basic structural and functional unit of the nervous system.
  • Nerve impulse: an electrochemical signal travelling along a nerve fibre and across a synapse to stimulate/inhibit an effector.
  • Reflex action: a rapid, automatic, involuntary, unlearned response to a stimulus.
  • Nerve fibre: a thread-like process arising from a neuron’s cell body; a nerve is a bundle of many nerve fibres.

The nervous system uses electrochemical impulses (fast, brief, localised); the endocrine system uses hormones in the blood (slow, long-lasting, widespread).

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