Neurones And Synaptic Transmission Flashcards
List the three types of neurones
Motor, relay and sensory
Describe the cell body
Contains nucleus (genetic material)
Describe dendrites
Branchlike structures that project out from cell body
Carries impulses from dendrites to cell body
Describe the axon
Axon carries impulses away from the cell body down the length of the neurone. Covered in fatty layer called myelin sheath causing electrical impulse to speed up.
What are the gaps in myelin called?
Nodes of ranvier
What is at the end of the axon?
Terminal buttons (then the synapse)
What kind of conduction is this (myelin)
Saltatory conduction
Where are motor neurones located?
In the CNS but have long axons which form part of the PNS
Where are sensory neurones located?
Outside the CNS and located in the PNS in clusters known as ganglia
What % of relay neurones make up all neurones?
97%
What is the inside of the axon when resting?
Relatively negative
What charge does the axon become when an action potential fired?
Positive
Briefly explain chemical transmission in presynaptic membrane
When an electrical impulse reaches the end of a neurone (presynaptic membrane/ knob) it triggers release of neurotransmitters from synaptic vesicles. Across synaptic cleft.
What are neurotransmitters?
Are chemicals that diffuse across the synapse to the next neurone in the chain.
Where are neurotransmitters taken up?
Postsynaptic membrane
Can action potentials travel both ways?
No— one direction
Give an example of a neurotransmitter
Acetylcholine (found where a neurone meets a muscle)
Neurotransmitters can be either… blank or blank
Excitatory or inhibitory
What is serotonin (inhibitory or exhibitory)
Causes inhibition (makes it more negatively charged)
What is adrenaline (inhibitory or exhibitory)
Exhibitory (makes more positive)
Describe summation
Wether a postsynaptic neurone fires is decided by the process of summation. Excitatory and inhibitory influences are summed
Eg. If net is more excitatory more likely AP fired.
Must meet THRESHOLD
