The structure and function of sensory, relay, motor neurons

• What are the three main types of neurons?


  Sensory, Motor, Relay
• Function of sensory neurons


  Found in receptors such as the eyes, ears, tongue and skin, and carry nerve impulses to the spinal cord and brain. When these nerve impulses reach the brain, they are translated into 'sensations', such as vision, hearing, taste and touch. However, not all sensory neurons reach the brain, as some neurons stop at the spinal cord, allowing for quick reflex actions.

  
• Function of relay neurons


  Found between sensory input and motor output/response. Relay neurons are found in the brain and spinal cord and allow sensory and motor neurons to communicate.

  
• Function of motor neurons


  Found in the central nervous system (CNS) and control muscle movements. When motor neurons are stimulated they release neurotransmitters that bind to the receptors on muscles to trigger a response, which lead to movement.

  
• What is the role of dendrites?


  Receive signals from other neurons or from sensory receptor cells. The dendrites are typically connected to the cell body, which is often referred to as the 'control centre' of the neuron, as it's contains the nucleus.
• What is the role of the axon, and myelin sheath?


  Theaxonis a long slender fibre that carries nerve impulses, in the form of an electrical signal known asaction potential,away from the cell body towards the axon terminals, where the neuron ends. Most axons are surrounded by amyelin sheath(except for relay neurons) which insulates the axon so that the electrical impulses travel faster along the axon.
• Axon terminal


  Theaxonterminalconnects the neuron to other neurons (or directly to organs), using a process calledsynaptic transmission.