neurons and synaptic transmission

• what is a sensory neuron?

  carries messages from PNS to CNS and they have long dendrites and short axons.
• what is a relay neuron?

  connect the sensory neurons to the motor neurons and have short dendrites and short axons.
• what is a motor neuron?

  connect the CNS to effectors such as muscles or glands and have short dendrites and long axons.
• what is the basic structure of a neuron?

  -vary from less than a mm to a m long.

  -cell body with a nucleus

  -branchlike structures called dendrites

  -axon that's covered in myelin sheath

  -myelin sheath segmented by gaps called nodes of ranvier

  -at end of axon are terminal buttons that communicate with a synapse
• what is synaptic transmission?

  process by which neighbouring neurons communicate with each other by sending chemical messages across the synapse that seperates them
• what is excitation?

  when a neurotransmitter like adrenaline increases the positive charge of the post synaptic neuron. increases the likelihood that the postsynaptic neuron will pass on the electrical impulse.
• what is inhibition?

  when a neurotransmitter like serotonin increases the negative charge of the postsynaptic neuron. decreases the likelihood that the postsynaptic neuron will pass on the electrical impulse
• what is the process of synaptic transmission?

  Info passed down axon of neuron as an action potential. Once it reaches end of axon must cross over synaptic gap. At axon terminal are synaptic vesicles with neurotransmitters. When electrical impulse reaches this, they release their contents of neurotransmitters, which then carry signal across synaptic gap. They bind to receptor sites on post-synaptic cell that then become activated.

  Once receptors activated, they either produce excitatory or inhibitory effects making post-synaptic cell more/less likely to fire.