Neurons+Synaptic Transmisson

• Myelin sheath. This is a fatty layer that protects the axon and speeds up electrical transmission of the action potential. 
• Axon. This carries action potentials away from the cell body down the length of the neuron.
• Cell body.  This is the control centre of the neuron
• Nucleus. This contains genetic material of the cell.
• Dendrites. These carry nerve impulses from neighbouring neurons or sensory receptors to the cell body.
• Nodes . These are gaps in the myelin sheath that speed up transmission of the action potential by forcing the impulse to ‘jump’ across the gaps along the axon.
• •Motor neurons connect the CNS to effectors such as muscles and glands. They are located in the CNS and their axons project outside the CNS to directly or indirectly control muscles.
• •Neurons are cells of the nervous system that process and transmit messages through electrical and chemical signals.•They are specialised cells whose function is to move electrical impulses to and from the CNS.•The electrical impulses are called action potentials.
• •When a neuron is in a resting state, the inside of the cell is negatively charged compared to the outside.When a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur. This causes the electrical impulse to travel down the axon towards the end of the neuron
• 3 Main Types Of Neurons

  Sensory, Relay and Motor
• Synaptic Transmission


  Neurons communicate with each other within groups known as neural networks.

  Each neuron is separated from the next by a tiny gap called the synapse.

  Signals within neurons are transmitted electrically.

  Signals between neurons are transmitted chemically across the synapse in a process called synaptic transmission.
• Synaptic Transmission


  1. Action potential reaches presynaptic terminal

  2. Synaptic vesicles release neurotransmitters into synaptic gap

  3. Neurotransmitters diffuse across synaptic gap

  4. Neurotransmitters bind to postsynaptic receptor sites

  5. Stimulation of postsynaptic receptors converts chemical message to electrical impulse

  6. Effects terminated by reuptake
• Presynaptic terminal (terminal button)

  Where the action potential triggers the release of neurotransmitters
• Synaptic vesicles


  Contain neurotransmitters that are released into the synaptic gap
• Neurotransmitters


  Chemicals released into the synaptic gap
• Synaptic vesicles


  Contain neurotransmitters that are released into the synaptic gap
• Neurotransmitters


  Chemicals released into the synaptic gap
• Synaptic gap


  Space between the pre and post-synaptic cells
• Post-synaptic receptor sites


  On the membrane of the post-synaptic neuron's dendrite, where the neurotransmitters bind
• Post-synaptic receptor sites


  On the membrane of the post-synaptic neuron's dendrite, where neurotransmitters bind
• Reuptake


  Process that terminates the effects of neurotransmitters, where they are taken up by the presynaptic neuron and stored in synaptic vesicles
• Excitatory neurotransmitters


  •Neurotransmitters can be excitatory (e.g. adrenaline and noradrenaline) or inhibitory (e.g. serotonin and GABA).•If the neurotransmitter is excitatory, this causes excitation of the post-synaptic membrane (excitatory post-synaptic potentials), and so the post-synaptic neuron is more likely to fire an electrical impulse.
• inhibitory neurotransmitters


  •potentials), and so the post-synaptic neuron is less likely to fire an electrical impulse.•The excitatory and inhibitory influences are summed (summation); if the net effect on the post synaptic neuron is inhibitory, the neuron will be less likely to fire and if the net effect is excitatory, the neuron will be more likely to fire.•