Structure of neurons

• What are neurons?

  Nerve cells that process and transmit messages through electrical and chemical signals
• What do sensory neurons do?

  Carry messages from the Peripheral nervous system to the central nervous system. They have long dendrites and short axons
• What do relay neurons do?

  Connect the sensory neurons to the motor or other relay neurons. They have short dendrites and short axons
• What do motor neurons do?

  Connect the central nervous system to effectors such as muscles and glands. They have short dendrite and long axons
• What does the cell body include?

  A nucleus, which contains the genetic material of the cell
• Branch-like structures called dendrites protrude from the cell body
• What do dendrites do?

  Carry nerve impulses from neighbouring neurons towards the cell body
• What does the axon do?

  Carries the impulses away from the cell body down the length of the neuron
• What is the axon covered by?

  Myelin sheath which protects the axon and speeds up electrical transmissions of the impulse
• What are the gaps in the myelin sheath called?

  Nodes of Ranvier. These speed up the transmission of the impulse by forcing it to ‘jump’ across the gaps along the axon
• At the end of the axon are terminal buttons that communicate with the next neuron in the chain across the synapse
• When a neuron is in a resting state, the inside of the cell is negatively charged compared to the outside. When the neuron is 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
• Electric transmission: firing of a neuron

  When a neuron is in a resting state, the inside of the cell is negatively charged compared to the outside. When the neuron is 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