nervous system

• homeostasis

  the regulation of internal conditions within an organism, in response to external changes.
• why is homeostasis important?

  for maintaining optimal conditions for enzyme action and all cell functions.
• what does homeostasis control in the human body?

  control of blood glucose concentration, body temperature and water levels
• the demands of a control system

  all automatic control systems may involve nervous or chemical responses. they include receptors, coordination centres and effectors.
• what are coordination centres?

  areas that receive and process the information from the receptors. they send out signals and coordinate the response of the body. the brain is a major coordination centre
• what are receptors?

  cells that detect changes in the internal or external environment called stimuli. receptors may be part of the nervous system or hormonal control systems of the body
• what are effectors?

  muscles or glands that bring about responses to the stimulus that has been received. these responses restore conditions in the body to the optimum levels
• summed up nervous system

  stimulus - receptor - sensory neurones - cns - motor neurones - effector - response
• three types of neurones that reflexes include?

  sensory, motor and relay

  relay neurones connect a sensory and a motor neurone. found in cns
• synapses and how do they work?

  there are junctions between neurones called synapses which form physical gaps between the neurones.

  
• reflex actions


  they are automatic and rapid and do not involve the conscious parts of the brain
• stages of reflex arc

  stimulus - receptor - sensory neurone - relay neurone - motor neurone - effector - response