Synaptic Transmission

• sensory neuron

  send info from the senses to the brain - detected by sensory receptores (via the PNS)
• relay neuron

  connect with other neurons, mostly found in. the brain - involved in analysis of the sensations, deciding how to respond (acting between motor and sensory)
• motor

  send messages via axons away from the brain to the muscles/effectors - have the message from the brain instruct action to perform
• structure + function of a neuron

  neurons enable communication within the NS

  the cell body (soma) contains the genetic material. branch-like dendrites extend from the cell body and carry functional info from the other neurons

  axons carry messages away from the cell body

  terminal buttons are at the end of axons, these make synaptic connections with other cells

  axon terminals contain neurotransmitters
• neurons can only transmit info in one direction

  the synaptic vesicles containing the neurotransmitter are only present on the presynaptic membrane

  the receptors of the neurotransmitter are only present on the post synaptic membrane

  it is the binding of the neurotransmitter to the receptor which enables the info to be passed on
• synaptic transmission

  electrical impulses (action potentials) reach the presynaptic terminal, triggering the release of neurotransmitters into the synaptic cleft

  these neurotransmitters cross the synapse from vesicles and combine with receptors on the postsynaptic membrane

  stimulation of postsynaptic membrane results in either excitation or inhibition
• summation

  neurotransmitters can be excitatory or inhibitory

  if the NT is excitatory, the postsynaptic neuron is more likely to fire

  if the NT is inhibitory, the postsynaptic neuron is less likely to fire

  the excitatory and inhibitory influences is summed, if the net effect is inhibitory - neuron less likely to fire, if net effect is excitatory - neuron more likely to fire