Neurons And Synaptic Transmission Flashcards
(25 cards)
What are the primary means of communication in the nervous system?
Electrical and chemical signals transmitted by neurons.
What are the three types of neurons?
Sensory neurons, relay neurons, and motor neurons.
How long can neurons be?
From less than a millimetre to up to a metre long.
What is the role of the cell body in a neuron?
Contains the nucleus, which holds the genetic material.
What do dendrites do?
Carry nerve impulses from neighbouring neurons to the cell body.
What is the function of the axon?
Carries impulses away from the cell body down the neuron.
What is the myelin sheath?
A fatty layer covering the axon that protects it and speeds up transmission.
Why are there nodes of Ranvier in the axon?
To allow the impulse to ‘jump’ and speed up transmission.
What are terminal buttons?
End of the axon that communicates with the next neuron across the synapse.
Where are the cell bodies of motor neurons located?
In the CNS, with long axons forming part of the PNS.
Where are sensory neurons found?
In the PNS, in clusters called ganglia.
Where are most relay neurons located?
In the brain and the visual system (they make up 97% of all neurons).
What is the charge of a neuron at rest?
The inside is negatively charged compared to the outside.
What happens when a neuron is activated?
The inside becomes positively charged for a split second, causing an action potential.
What does an action potential do?
Creates an electrical impulse that travels down the axon.
What happens when an electrical impulse reaches the end of the presynaptic neuron?
It triggers the release of neurotransmitters from synaptic vesicles.
Where do the neurotransmitters go after being released?
They diffuse across the synaptic cleft.
What happens when neurotransmitters reach the postsynaptic neuron?
They bind to specific receptors on the dendrites, triggering a new electrical impulse.
What breaks down leftover neurotransmitters in the synapse?
Enzymes are released to break them down.
What is reuptake in synaptic transmission?
Excess neurotransmitters are reabsorbed by the presynaptic neuron.
What happens to synaptic vesicles after neurotransmission?
They are replenished with recycled neurotransmitters, ready for the next impulse.
What is the difference between excitatory and inhibitory neurotransmitters?
Excitatory (e.g., adrenaline) increase the positive charge of the postsynaptic neuron; inhibitory (e.g., serotonin) decrease it.
What does summation mean in synaptic transmission?
The combined effect of excitatory and inhibitory neurotransmitters determines whether the neuron will fire.
When are neurons more likely to fire?
When excitatory input outweighs inhibitory input.
