Nervous system

• What does the nervous system do?


  Enable us to react to changes in in the surrounding environment by passing on and coordinating information
• Nerve cells are called neurones. They are specialised to pass information around the body as electrical impulses
• Why do neurones have a branched structure?


  It enables information t be passed on to lots of different cells
• What makes up the central nervous system?


  The brain and spinal cord
• Neurones pass on electrical impulses between the different parts of the nervous system
• What do the receptor cells do?

  Detect changes in the environment
• What does the coordinator do?

  Process information
• What do the effector cells do?


  Carry out the response (have an effect)
• What is a change in the environment called?

  Stimulus
• What do the muscle effector cells cause?


  Movement
• What do the gland effector cells release?


  Chemicals
• What are reflex actions?


  They are fast and automatic and are coordinated by the subconscious part of the brain and spinal cord
• What are examples of reflex actions?


  moving your hand away from a hot object or pupil getting bigger and smaller in response to light
• Reflex reactions are important because the protect us from harm
• Describe the reflex arc

  The stimulus is detected by the receptor cells, this information travels down the sensory neurone to the CNS via electrical impulse. This then diffuses across the synapse to the relay neurone where it diffuses across another synapse then down the motor neurone to the effector cells
• What is a synapse?


  A gap between two neurones. Electrical impulses cannot travel across the synapse so instead a chemical is released.
• The synapse is the slowest part of the reflex arc