Neurons & Synaptic Transmission

• What are the three types of neurons and their functions?

  • Sensory neurons: Carry nerve impulses from sensory receptors to the spinal cord and brain.
  • Relay neurons: Allow communication between sensory and motor neurons.
  • Motor neurons: Form synapses with muscles and control their contractions.
• Neurons - cells that are specialised to carry neural information throughout the body in the form of electric current
• Sensory neurons - carry nerve impulses from sensory receptors to the spinal cord & brain
• Relay neurons - allow sensory & motor neurons to communicate with each other
• Motor neurons - form synapses with muscles & control their contractions
• 1. Dendrite - receive signals from other neurons or sensory receptors
  2. Nucleus
  3. Cell body
  4. Axon
  5. Myelin sheath - insulating layer that allows nerve impulses to transmit more quickly
  6. Node of ranvier - allow nerve impulses to transmit quicker
  7. Axon terminal

  
• Synaptic Transmission - a nerve impulse passes across the synaptic cleft, from the presynaptic neuron to the postsynaptic neuron
• Synaptic Transmission:

  1. An electrical impulse triggers the nerve ending of the presynaptic neuron to release neurotransmitters
  2. These diffuse across the synapse & bind with receptor molecules on the membrane of the next neuron
  3. This stimulates the second neuron to transmit the electrical impulse
  4. Reuptake: the neurotransmitter is reabsorbed in the vescicles of the pre-synaptic neuron
• Inhibitory neurotransmitters - decrease the likelihood of the neuron firing by making the neuron more negatively charged.
• Inhibitory neurotransmitters act as 'off switches'
• Excitatory neurotransmitters increase the likelihood of the neuron firing by making it more positively charged.
• Excitatory neurotransmitters act as 'on switches'.