Neurons & Neurotransmission

• (AO1) What are the 3 main types of neurons?

  Sensory, Motor and Relay
• (AO1) Where are sensory neurons found? What is their function? What is their structure?

  Found = Receptors (eyes, ears, tongue, skin)

  Functions:

  1)Carry information about the internal and external environment to the brain.

  2)Carry nerve impulses to the brain and spinal cord +

  How: = When nerve impulses reach brain, translated into 'sensations' (vision, hearing, taste, touch). HOWEVER, not all sensory neurons reach brain, as some neurons stop at spinal cord for quick reflex actions.+

  Structure = Cell body always located in middle of axon
• (AO1) Where are sensory neurons found? What is their functions? What is their structure?

  Found = Receptors (eyes, ears, tongue, skin)

  Functions:

  1)Carry information about the internal and external environment to the brain.

  2)Carry nerve impulses to the brain and spinal cord

  How = When nerve impulses reach brain, translated into 'sensations' (vision, hearing, taste, touch). HOWEVER, not all sensory neurons reach brain, as some neurons stop at spinal cord for quick reflex actions.

  Structure = Cell body always located in middle of axon
• (AO1) Where are motor neurons found? What is their functions? What is their structure?

  Found = CNS

  
  

  Functions:

  1)Carry messages from the CNS to organs and muscles in the body

  2)Control muscle movements

  How = When motor neurons are stimulated, they release neurotransmitters that bind to receptors on muscles to trigger a response = leads to a movement.

  
  

  Structure = has a traditional neuron shape.
• (AO1) Where are relay neurons found? What is their functions? What is their structure?

  Found = Between sensory input and motor output / response (found in brain and spinal cord)

  Functions:

  1)Carry messages from one part of the CNS to another.

  2)They connect sensory and motor neurons - communicate

  Structure = No cell body, no myelin sheath, long axon
• (AO1) Draw out a sensory, motor and relay neuron

  Diagrams:

  A) Receptor Cell

  B) Axon

  C) Myelin sheath

  D) Cell body

  E) Dendrite

  F) Cell body

  G) Axon

  H) Pre synaptic terminal

  I) Dendrite

  J) Cell body

  K) Axon

  L) Myelin sheath

  M) Neurofibril Node

  
• (AO1) Define the first 4 processes of neurotransmission

  This is the process of neurons communicating, messaging one neuron to another.

  1)Info is passed down the presynaptic neuron by the axon as electrical impulses known as action potential.

  2)At the end of the neuron (in the axon terminal) are synaptic vessels which contain chemical messengers known as neurotransmitters.

  3)When electrical impulses (action potential) reach the synaptic vessels, they release their content of neurotransmitters.

  4)The neurotransmitters then diffuse and carry the signal across the synaptic gap
• (AO1) Define the last 2 processes of neurotransmission

  5)They then bind to receptors on the post synaptic cell that then become activated

  6)Once the receptors have been activated, they either produce excitatory or inhibitory effects on the post synaptic cell
• (AO1) Define excitatory and inhibitory

  If an excitatory neurotransmitter like noradrenaline binds to the post synaptic receptors, it will result in an electrical charge in the cell membrane which results in a excitatory post synaptic potential (ESPS) = making the post synaptic cell MORE likely to fire.

  If an inhibitory neurotransmitter like GABA binds to the post synaptic receptor, it will result in a inhibitory post synaptic potential (ISPS) = making the post synaptic cell LESS likely to fire
• (AO1) What is the final step in neurotransmission?

  The neurotransmitters then form a sum total together, the net effect then determines the action.