Nervous system

• State 3 things that homeostasis controls in the human body:

  • Blood glucose concentration
  • Body temperature
  • Water levels
• State 2 Automatic control systems

  • Nervous system (Nervous responses)
  • Endocrine system (Chemical responses)
• What does the nervous system consist of?

  • The central nervous system (Brain and spinal cord)
  • Peripheral nervous system (Nerve cells that carry information to or from the CNS’)
• State the role of receptors

  • Cells which detects stimuli (A change in the environment)
• State the role of the coordination centre:

  Receives and processes information from receptors around the body
• State the role of effectors

  Bring about responses which restore optimum levels, e.g Body temperature and glucose levels.
• Name 2 receptors.

  Muscles and glands
• State the name of nerve cells and their function

  Neurones, which are adapted to carry electrical impulses from one place to another.
• State the function of a fibre axon of a neuron.

  A long fibre axon insulated by a fatty myelin sheath which are long and can carry messages up and down the body.
• State the function of dendrons of a neurone.

  Tiny branches which branch further as dendrites at each end which receive incoming impulses from other neurones
• State the three types of neurone

  Sensory, motor and relay
• State the order of how information flows from the receptors to the effectors.

  Stimulus -> Receptor -> Coordinator -> Effector -> Response
• Define reflex action

  An automatic and rapid response to a stimulus
• Reflex arcs require..

  No conscious thought
• State the nerve pathway of a reflex arc.


  Receptor cells in the skin detect a stimulus. The sensory neurone sends electrical impulses to the relay neurone which is located in the spinal cord. The motor neurone sends electrical impulses to an effector. The effector then produces a reponse.
• Define synapse

  A gap where neurones meet
• State what happens at the synapse:

  An electrical impulse travels along the first axon which triggers the nerve ending of a neurone to release chemical messengers called neurotransmitters. The neurotransmitters diffuse across the synapse and bind with the receptor molecules . This stimulates the second neurone to transmit an electrical impulse.
• State 2 control variables in measuring somebody’s reaction time

  • Drop the ruler from the same height
  • Drop the ruler without any force each time
• State two ways in which reflex actions are different than one controlled by hormones

  Reflex actions are quicker. Reflex actions involve impulses and hormone involves chemicals.