nervous system

• Nerve cell


  Also called a neuron
• Nerve cell


  • Long
  • Thin
  • Lots of branch connections to either end
  • Adapted to carry electrical impulses from one point to another
• Synapse

  Connection between nerve cells where electrical impulses are converted to chemical signals to pass between cells
• Nerve cell communication


  1. Electrical impulse hits end of nerve

  2. Causes release of chemicals

  3. Chemicals diffuse across gap to next nerve cell

  4. Triggers another electrical impulse

  5. Electrical impulse continues along new neuron
• Central nervous system


  • Made up of brain and spinal cord
  • Where 'thinking' takes place
  • Takes in sensory information
  • Decides what needs to be done
  • Sends out orders to the rest of the body
• Sensory neurons

  Carry information from receptors all over the body to the central nervous system
• Motor neurons

  Carry impulses from the central nervous system to effectors (muscles or glands)
• Reflex arc

  • Nerve pathway that causes reflexes
  • Rapid and automatic response to stimuli
• Reflex arc example

  1. Pressure of sharp object detected by receptor cells in skin

  2. Sensory neuron carries impulse to spinal cord

  3. Relay neuron transfers impulse to motor neuron

  4. Motor neuron carries impulse to effector (bicep) to move hand away
• What passes along nerve cells?

  Electrical impulses
• What is the gap between two neurones called?


  Synapse
• What is released across a synapse?

  Chemicals
• Which of these is part of the central nervous system (CNS)?

  Spinal cord, Brain
• What is the role of a receptor?

  To detect and respond to specific stimuli.
• What is the role of a sensory neuron?

  To transfer a signal from a receptor to the CNS (Central Nervous System)
• What is the role of a motor neurone?


  To transmit signals from the central nervous system to an effector (muscles or glands)
• What is the role of a relay neurone?


  To transmit electrical signals from sensory to motor neurons.
• What is a reflex?


  An automatic response to a stimulus
• What are the two main types of effectors? 


  Muscles (To contract)

  Glands (Release hormones)
• Reflexes are...


  Fast

  Automatic
• Why are reflexes important? 


  They protect us from harm.
• Receptor

  
• Sensory Neuron

  
• Relay Neuron

  
• Effector

  
• What chemical is released into the Synapse?


  Neurotransmitter
• Some nerves are myelinated
• What is the advantage of a myelinated cell?


  It allows the nerve transmission to travel faster.
• The neurones (nerve cells)


  Neurones (nerve cells) carry electrical impulses (signals) between receptors, the central nervous system (CNS) and effectors.
• Examples of reflexes are:

  Blinking, Sneezing, Dropping hot objects.
• Stimulus


  • A stimulus can be any change in the environment to which the body needs to respond.
  • The stimulus is detected by a receptor.
• There are three types of neurone (nerve cells):


  The sensory neurone

  The relay neurone (in the CNS)

  The motor neurone
• The sensory neurone

  as

  Carries the signal as an electrical impulse to the central nervous system (CNS).
• The relay neurone 


  Relays the electrical impulse from the sensory neurone to the appropriate motor neurone.
• The motor neurone 


  Carries the electrical impulse from the CNS to an effector.