Nervous System

• Divisions of the nervous system: Central Nervous System (Brain and Spinal Cord) and Peripheral Nervous System
• Divisions of the PNS:

  • Motor neurons - CNS to muscles and glands
  • sensory neurons - Sensory organs to CNS
• Divisions of the Motor Neurones:

  • somatic NS - controls voluntary movements
  • Autonomic NS - controls involuntary movements
• Divisions of the Autonomic NS:

  • Sympathectic division - “fight or flight”, increases heart rate, blood rate and blood pressure
  • parasympathetic division - “rest and digest”, calms the body down and allows normal resting functions to resume
• The nervous system regulates physiological processes and relays information to and from the brain around the body
• Somatic NS

  • 12 pairs of cranial nerves
  • 13 pairs of spinal nerves
  • sensory and relay neurons
  • motor neurons relay messages from the CNS to other areas of the body
  • responsible for reflex actions
• Sympathetic division released Noradrenalin
• Parasympathetic division releases Acetylcholine
• Autonomic NS

  • involuntary actions
  • unconscious decision making
  • heart beating/ breathing/ digestion
• Neurons - specialised cells that move electrical impulses to and from CNS
• Average human brain contains 1000 billion neurons, and each neuron is connected to 1,000 other neurons
• Dendrite 


  where a neuron received impulses from other cells
• Axon


  connects neurons for communication
• Axon terminal


  makes synaptic contact with other cells
• Myelin sheath


  allows electrical impulses to transmit quickly and efficiently
• Schwann Cell


  development, maintenance, function and regeneration of nerves
• Node of Ranvier

  Allows the generation of fast electrical impulses along the axon
• Sensory Neuron


  carry nerve impulses from sensory receptors (eyes, ears, skin) to the brain
• Relay neuron 


  Allows sensory and motor neurons to communicate with eachother
• Motor neuron 


  release neurotransmitters from the brain that bind to receptors and trigger responses
• Synaptic transmission

  1. Action potential reaches axon terminal
  2. Vessicles stimulated and release NTs
  3. NTs diffuse across synapse
  4. NTs bind with post synaptic receptors
  5. Summation occurs when the next cell is inhibited or excited
  6. Remaining NTs is recycled by enzymes our reuptake occurs
• Excitatory NTs - Noradrenalin and acetylcholine
• Inhibitory NTs - serotonin and GABA