HSB-NEVOUS SYSTEM

• NERVOUS SYSTEM-What is the CNS Central Nervous System composed of?

  Brain and spinal cord
• NERVOUS SYSTEM-What is the PNS Peripheral Nervous System composed of?

  NERVES- paired cranial nerves and paired spinal nerves
• NERVOUS SYSTEM- Receptors (examples as well)


  Receive stimuli (sense organs)

  ears, nose, skin, eyes
• NERVOUS SYSTEM- Effectors


  responds to stimuli (muscles
• NERVOUS SYSTEM-Hormones 


  Chemical messages carried by blood(coordinates activities)
• NERVOUS SYSTEM-Neurone 


  nerve cell

  surrounded by myelin sheath

  DENDRON (nerve fibre) conducts impulses towards the cell body

  AXON- conducts impulses away from the cel body
• NERVOUS SYSTEM-What is a DENDRON


  DENDRON (nerve fibre) conducts impulses towards the cell body
• NERVOUS SYSTEM-What is an AXON


  AXON- conducts impulses away from the celL body
• NERVOUS SYSTEM-Why are the AXON and DENDRON surrounded by MYELIN SHEATH?

  insulation

  electrical impulse passes rapidly jumps from node to node
• NERVOUS SYSTEM-What is MYELIN SHEATH?

  fatty insulating layer around nerve cells.
• NEVOUS SYSTEM- 3 TYPES OF NEURONS

  Motor neurone

  Sensory nerurone

  Intermediate/Relay neurone
• NERVOUS SYSTEM-NODE OF RANVIER

  Spaces between myelin sheath

  helps with electrical impulses (jumps from node to node)
• NERVOUS SYSTEM-MOTOR NEURONE


  impulses outward from CNS to effector organ
• NERVOUS SYSTEM- DENDRITES


  Connects sensory to mother neurones
• NERVOUS SYSTEM-NODES


  Speeds up connection
• NERVOUS SYSTEM-SYNAPSES EXPLAINED NERVE IMPULSES

  1. impulse passes when axon membrane becomes permieable to sodium ions
  2. positive ions flow making axon positive
  3. flow of ions along axon transmits impulse
  4. metabolic activity pumps sodium ions to restore
  5. during recovery no impulse can pass
• NERVOUS SYSTEM- SYNAPSE


  where one nerve connects with another

  impulse must pass a small gap (as a chemical)

  can occur between neurone and muscle
• NERVOUS SYSTEM-SYNAPSE (NEURONE AND MUSCLE)

  1. muscle fibre is modified to form endplate
  2. impulse causes synaptic vesticle to attach to the membrane and discharge contents into synaptic gap
  3. acetycholine from vesticles diffuses across gap causing impulse in memebrane to next nerve