neurons + synaptic transmission Flashcards
What are the three types of neurons?
Sensory neuron, Relay neuron, Motor neuron
What does the cell body of a neuron contain?
3 nuclei, which contain the genetic material of the cell
What is the function of dendrites?
Carry nerve impulses from neighbouring neurons towards the cell body
What carries impulses away from the cell body?
The axon
What is the function of the myelin sheath?
Protects the axon and speeds up electrical transmission of the impulse
What are the gaps in the myelin sheath called?
Nodes of Ranvier
What is the role of the nodes of Ranvier?
Speed up the transmission of the impulse by forcing it to jump across the gaps along the axon
Where are motor neurons located?
In the CNS but have long axons forming part of the PNS
Where are sensory neurons located?
Outside of the CNS, in the PNS in clusters known as ganglia
What percentage of all neurons are relay neurons?
97%
Where are most relay neurons found?
In the brain and in the visual system
What charge does a neuron have in its resting state?
Negatively charged inside compared to the outside
What happens when a neuron is activated by a stimulus?
The inside of the cell becomes positively charged, causing an action potential
What does an action potential create?
An electrical impulse that travels down the axon
What is a synapse?
-gaps between neurons
What is the process of synaptic transmission?
1-Information is passed down the axon of the neuron as an electrical impulse known as action potential
2-This triggers the nerve-ending of the pre-synaptic neuron to release chemical messengers called neurotransmitters
3-These chemicals diffuse across the synapse and bind with receptor molecules on the membrane of the next neuron
4-Receptor molecules on the second neuron bind only to the specific chemicals released from the first neuron. This stimulates the second neuron to transmit the electrical impulse
5-The NT is reabsorbed in the vesicles of the pre-synaptic neuron after it has performed its function of transmitting a neural impulse
What are the two effects a neurotransmitter can have on the post-synaptic neuron?
-excitatory or inhibitory
What is excitation?
-when receptor stimulation results in an increase in the positive charge of the postsynaptic neuron and increases the likelihood of the neuron firing and passing on the electrical impulse.
What is inhibition?
-when receptor stimulation results in an increase in he negative charge of the postsynaptic neuron and decreases the likelihood of the neuron firing and passing on the electrical impulse.
