• Neurones?are specialised cells of the nervous system which carry?electrical impulses?around the body
• A bundle of neurones is known as a?nerve
• There are different types of neurones, but the following features are found in all types
  • A?long fibre?known as an?axon
  • A?cell body?that contains the?nucleus?and other cellular structures
  • The end of the axon, known as the?axon terminal,?has many nerve endings
    • The?nerve endings at the axon terminals?allow neurones to?connect?to and?receive?impulses?from?other?neurones, forming a?network?for easy?communication
• Some neurones are?myelinated, meaning that their axon is?insulated?by a fatty layer known as the?myelin?sheath
  • The myelin sheath is made up of specialised cells known as?Schwann cells?which wrap themselves around the axon
  • There are?uninsulated gaps?between the Schwann cells known as the?nodes of Ranvier
  • Electrical impulses in myelinated cells do not travel down the whole axon, but jump from one?node?to the next, speeding up impulse transmission
• In?non-myelinated neurones?the axon is not insulated by Schwann cells
  • The impulse travels more slowly as it moves through the entire length of the axon

Neurones have a long axon, a cell body, and an axon terminal, and some neurones are myelinated

• There are?three main types?of neurones
  • Sensory?neurones?carry impulses from?receptors?to the brain and spinal cord in the?CNS
  • Relay neurones?are found entirely within the CNS and?connect?sensory?and?motor?neurones
  • Motor?neurones?carry impulses from the?CNS?to?effector?muscles or glands
• Each type of neurone has a?slightly different structure
  • Motor neurones
    • A large?cell body at one end?that lies within the spinal cord or brain
    • Many highly-branched?dendrites?extending from the cell body, providing many connections with the axon terminals of other neurones
  • Relay neurones
    • Short neurones with axons and highly branched dendrites
  • Sensory neurones
    • A?cell body?that branches off in the?middle?of the axon and has?no dendrites
    • The axon terminal is attached to a?receptor cell
    • The section of neurone that links the axon terminal with the cell body is known as a?dendron
    • The section of neurone that connects the cell body with the CNS is the?axon

Different types of neurone differ in both structure and function