neurons and synaptic transmission Flashcards

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1
Q

What is a neuron?

A

the basic building blocks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals

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2
Q

what are sensory neurons?

A

these carry messages from the PNS to the CNS. they have long dendrites and short axons

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3
Q

what are relay neurons?

A

these connect the sensory neurons to the motor or other relay neurons. they have short dendrites and short axons

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4
Q

what are motor neurons?

A

these connect the CNS to effectors such as muscles and glands. they have short dendrites and long axons.

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5
Q

draw a diagram of the 3 neurons

A
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6
Q

what does the cell body (soma) include?

A

a nucleus, which contains the generic material of the cell

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7
Q

what do dendrites do?

A

protrude from the cell body, they cary neural impulses from neighbouring neurons towards the cell body

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8
Q

what does the axon do?

A

carries impulses away from the cell body down the length of the neuron

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9
Q

what does the myelin sheath do?

A

covers the axon, protecting it, and speeds up electrical transmission of the impulse

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10
Q

what is the function of the nodes of ranvier?

A

they speed up the transmission of the impulse by forcing it to ‘jump’ across the gaps along the axon

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11
Q

what do the terminal buttons do?

A

they are located at the end of the axon and communicate with the next neuron in the chain across a gap known as the synapse

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12
Q

when a neuron is resting what is the charge of the inside?

A

it’s negatively charged compared to the outside

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13
Q

what happens to a neuron when it is activated by a stimulus?

A

the inside of the cell becomes positively charged for a split second causing an action potential to occur. this creates an electrical impulse that travels down the axon towards the end of the neuron

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14
Q

signals within neurons are transmitted..

A

electrically

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15
Q

signals between neurons are transmitted…

A

chemically across the synapse

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16
Q

what happens when the electrical impulse reaches the end of the neuron?

A

when it reaches the presynaptic terminal it triggers the release of a neurotransmitter from tiny sacs called synaptic vesicles

17
Q

what is synaptic transmission?

A

the process by which neighbouring neurons communicate with each other by sending chemical messages across the synapse that separates them

18
Q

what is a neurotransmitter?

A

a chemical that diffuse across the synapse to the next neuron in the chain

19
Q

once the neurotransmitter crosses the synapse, what is it taken up by?

A

the postsynaptic receptor site (the dendrites of the next neuron)

20
Q

what happens in the postsynaptic receptor site?

A

the chemical message is converted back into an electrical impulse and the process of transmission begins again in this other neuron

21
Q

what way is the direction of transmission?

A

axons -> dendrites

22
Q

what is excitation?

A

when a neurotransmitter, such as noradrenaline, increases the positive charge of the postsynaptic neuron. this increases the likelihood that the neuron will fire and pass on the electrical impulse

23
Q

what is inhibition?

A

when a neurotransmitter, such as seretonin, increases the negative charge of the postsynaptic neuron. this decreases the likelihood that the neuron will fire and pass on the electrical impulse.

24
Q

what are the lengths of the dendrites and axons in a sensory neuron?

A

-long dendrites
-short axons

25
Q

what are the lengths of the dendrites and axons in a relay neuron?

A

-short dendrites
-short axons

26
Q

what are the lengths of the dendrites and axons in a motor neuron?

A

-short dendrites
-long axons