The structure and function of neurons

• The Structure and Functions of neurons

  The are 100 billion neurons in human nervous system, 80% are located in the brain. By transmitting signals electrically and chemically, these neurons provide the nervous system with its primary means of communication.
• The Structure and Functions of neurons 2

  Types of neuron

  Three types: motor, sensory and relay.

  
• The Structure and Functions of neurons 3

  The structure of a neuron

  Vary from mm to metre.

  The cell body (soma) includes a nucleus which contains genetic material of cell. Branch-like structures called dendrites protrude from cell body. These carry nerve impulses from neighbouring neurons towards cell body.
• The Structure and Functions of neurons 4

  The structure of a neuron 2

  The axon carries impulses away from cell body down the length of neuron. Covered in a fatty layer of myelin sheath that protects the axon and speeds up electrical transmission of impulse.
• The Structure and Functions of neurons 5

  The structure of a neuron 3

  If the myelin sheath was continuous this would slow down the electrical impulse. So segmented by gaps called nodes of Ranvier. These speed up the transmission of the impulse by forcing it to jump across 'gaps' along the axon.
• The Structure and Functions of neurons 6

  The structure of a neuron 4

  Finally, at the end of the axon are terminal buttons that communicate with the next neuron across the gap known as the synapse.
• The Structure and Functions of neurons 7

  Electric transmission - firing of a neuron

  When neuron is in a resting state the inside of the cell is negatively charged compared to the outside. When activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur. This creates an electrical impulse that travels down the axon towards the end of the neuron.