Neurons

• Sensory neuron- carries impulses from PNS to CNS, long dendrites, short axons

  A) long

  B) dendrites

  C) cell-body

  D) short

  E) axon

  F) nerve

  G) impulses

  H) nerve

  
• Motor neuron- connects CNS to effectors, short dendrites, long axons

  A) long

  B) axon

  C) myelin

  D) short

  E) dendrite

  
• Relay neuron- connects sensory neurons to motor neurons or to other relay neurons, short dendrites, short axons

  A) cell-body

  B) short

  C) axon

  D) short

  E) dendrite

  
• Diagram of synaptic transmission:

  A) vesicles

  B) neurotransmitters

  C) axon

  D) terminal

  E) pre-synaptic

  F) post-synaptic

  G) receptors

  H) synapse

  I) dendrite

  J) post

  K) synaptic

  
• Synaptic transmission- can happen electrically or chemically:

  • Action potential arrives at axon terminal, neurotransmitters form in the vesicles.
  • When impulse reaches axon terminal, neurotransmitters form in the vesicles.
  • Vesicles move to the pre-synaptic cell membrane.
• Synaptic transmission- can happen electrically or chemically:

  • Neurotransmitters are released from vesicles into the synapse and diffuse across the synapse.
  • Receptors on the membrane of the post-synaptic neuron absorb the neurotransmitters and might trigger an action potential in the post-synaptic neuron.
  • Any remaining neurotransmitters in the synapse are reabsorbed and recycled by the pre-synaptic neuron.
• Synapse- gap between two neurons
• Dendrites- receives signals from receptors or other neurons
• Axon terminal- end of the neuron, releases neurotransmitters
• Cell body- contains the nucleus, controls the neuron
• Axon- carries the impulse across the neuron
• Myelin sheath- insulating layer that speeds up the impulse transmission
• Excitatory neurotransmitter- increases excitatory signal, which increases the likelihood of the neuron firing. When bound to the post-synaptic receptor, an electrical change happens resulting in excitatory post-synaptic potential (EPSP)
• Inhibitory neurotransmitter- filters out excitatory signal, which decreases the likelihood of the neuron firing. When bound to the post-synaptic receptor, a different electrical change happens resulting in an inhibitory post-synaptic potential (IPSP)
• Each neuron has thousands of synapses and can receive both EPSP'S and IPSP'S at the same time. The likelihood of the neuron firing is determined by adding up the EPSP'S and IPSP'S, known as summation.
• Excitation- more EPSP'S than IPSP'S, neuron fires an action potential
• Inhibition- more IPSP'S than EPSP'S, neuron inhibits an action potential and doesn't fire