Neurons And Synaptic Transmission Flashcards
What are the 9 parts of a neuron?
- put them in order of left it right
- receptors
- dendrites
- nucleus / cell body
- Axon (nodes of ranvier and myelin sheath)
- terminal buttons
- vesicles
What are the three types of neuron?
- Sensory
- Relay
- Motor
Describe the sensory neuron
- Unipolar
- carries messages from the PNS to the CNS
- long dendrites and small axons
Describe the relay neuron
- multipolar
- transfers messages from sensory neurons to other interconnecting neurons or motor neurons
- short dendrites and short or long axons
Describe the motor neuron
- multipolar
- carries messages from the CNS to effectors such as muscles and glands
- short dendrites and long axons
What is stage 1 and 2 of synaptic transmission?
1- when the dendrite picks up the message (NT) it sends an impulse through the cell body and along the axon to the terminal buttons
2- once an impulse has arrived at the terminal buttons at the end of the axon, it needs to be transferred to another neuron. To achieve this it must cross the synapse
What is stage 3 and 4 of synaptic transmission?
3- At the end of the terminal buttons there are synaptic vesicles that contain and store NT’s. These are chemical messengers that convert the electrical impulse to a chemical message that’s transferred to the next neuron
4- As the impulse travelling to the end of the neuron reaches the synaptic vesicle, they release the NT that then crossed the synaptic gap
What is stage 5 and 6 of synaptic transmission?
5- As the NT diffuses across the synaptic gap it binds to specialised receptors, on the dendrites of the next neuron, that recognise it and match that particular cell
6- Once the next cell is activated the receptor molecules produce either an excitatory or inhibitory effect at a post synaptic level
What is stage 7 and 8 of synaptic transmission?
7- Synaptic transmission is completed (in a fraction of a second) by a process called re-uptake. This is where the NT is taken back up / recycled by the pre-synaptic neuron
8 - After re-uptake has happened enzymes are released, they breakdown any thing left in the synapse
Summarise each 8 stages of synaptic transmission
- message is picked up, travels axon
- arrives at terminal buttons, must cross synapse
- vesicles with NT’s that convert electrical to chemical
- as impulse reaches end, NT released into synapse
- diffuses across, binds to specific receptor
- next cell activated, receptor causes excitatory or inhibitory effect
- re-uptake - NT taken back up by presynaptic neuron
- enzymes break down anything left
Neurotransmitters are defined as…
- Chemicals that are released from the end of brain cells (neurons) and allow them to communicate with each other and relay messages to different areas/structures of the brain
- examples : serotonin, dopamine
What is an excitatory effect ?
- If neurotransmitters create excitation of the post synaptic neuron they create a positive charge and make the neuron more likely to fire
- this rise in action potential will increase activity
- e.g. Glutamate
What is an Inhibitory effect?
- If neurotransmitters create inhibition of the post synaptic neuron, they create a negative charge and make the neuron less likely to fire
- this fall in action potential will decrease activity
- e.g. GABA
What is summation?
- The excitatory and inhibitory influences are summed
- 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
