neurons and synaptic transmission

Question 1

What is a neuron?

Answer 1

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

Question 2

what are sensory neurons?

Answer 2

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

Question 3

what are relay neurons?

Answer 3

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

Question 4

what are motor neurons?

Answer 4

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

Question 5

draw a diagram of the 3 neurons

Question 6

what does the cell body (soma) include?

Answer 6

a nucleus, which contains the generic material of the cell

Question 7

what do dendrites do?

Answer 7

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

Question 8

what does the axon do?

Answer 8

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

Question 9

what does the myelin sheath do?

Answer 9

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

Question 10

what is the function of the nodes of ranvier?

Answer 10

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

Question 11

what do the terminal buttons do?

Answer 11

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

Question 12

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

Answer 12

it’s negatively charged compared to the outside

Question 13

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

Answer 13

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

Question 14

signals within neurons are transmitted..

Answer 14

electrically

Question 15

signals between neurons are transmitted…

Answer 15

chemically across the synapse

Question 16

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

Answer 16

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

Question 17

what is synaptic transmission?

Answer 17

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

Question 18

what is a neurotransmitter?

Answer 18

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

Question 19

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

Answer 19

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

Question 20

what happens in the postsynaptic receptor site?

Answer 20

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

Question 21

what way is the direction of transmission?

Answer 21

axons -> dendrites

Question 22

what is excitation?

Answer 22

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

Question 23

what is inhibition?

Answer 23

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.

Question 24

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

Answer 24

-long dendrites
-short axons

Question 25

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

Answer 25

-short dendrites
-short axons

Question 26

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

Answer 26

-short dendrites
-long axons