structure and function of the human nervous system

• what is reaction time

  the interval between a stimulus and the initiation of a response
• what is reaction time measured in

  miliseconds
• what do all automatic resoponse systems have?

  a stimulus, receptor, coordination centre, effector and response
• what consists of the central nervous systm?

  brain and spinal cord
• what happens in an automatic response system?

  receptors detect a stimulus

  this sends electrical impulses down the neurones to the cns

  the cns sends electrical impulses down other neurones to effectors

  effectors bring about a response
• what are effectors?

  muscles or glands
• what does the nervous system enable humans to react to?

  their surroundings and help them coordinate behavior
• what happens in a reflex arc?

  a stimulus is detected by a receptor

  electrical impulses now pass from the receptor along a sensory neurone to the cns

  ( sensory neurone is connected to the receptors which allows us to detect our environment)

  at the end of the sensory neurone there is a junction cslled a synapse

  at the synapse a chemical is releaced and it diffuses across to a relay neurone in the cns

  this triggers an electrical impulse

  this passes across the relay neurone and reaches another synapse ( chemcal releaced, diffusion)

  chemical triggers an elecrtrical impulse in a motor neurone

  electrical impulse passed down the motor neurone to an effector

  muscle contract / gland secretes - response
• in the case of reflexes there is no

  decision making by the conscious part of the brain

  this makes the reflexes automatic and rapid

  this then helps protect from danger