Neurons and synaptic transmission Flashcards
1
Q
Neurons
A
Nerve cells that process and transmit messages through electrical and chemical signals
2
Q
What are the basic building blocks of the nervous system?
A
Neurons
3
Q
How many neurons are there in the human nervous system?
A
100 billion
4
Q
What are neurons also known as?
A
Nerve cells
5
Q
What do neurons do?
A
Transmit signals electrically and chemically
6
Q
Neurons provide the nervous system with…
A
its primary means of communication
7
Q
How many types of neurons are there?
A
3
8
Q
What are the 3 types of neurons?
A
Sensory, relay and motor
9
Q
What is the function of sensory neurons?
A
Carry messages from the PNS to the CNS
10
Q
Sensory neurons have long/short dendrites
A
long
11
Q
Sensory neurons have long/short axons
A
short
12
Q
Where are sensory neurons located?
A
Outside the CNS in the PNS, in clusters known as ganglia
13
Q
Sensory neurons are located in the PNS in clusters known as what?
A
Ganglia?
14
Q
What is the function of relay neurons?
A
Connect sensory neurons to the motor or other relay neurons
15
Q
Relay neurons have long/short dendrites
A
short
16
Q
Relay neurons have long/short axons
A
short
17
Q
Relay neurons make up what percentage of all neurons?
A
97%
18
Q
Where are most relay neurons found?
A
Within the brain and visual system
19
Q
What is the function of motor neurons?
A
Connect the CNS to effectors such as muscles and glands
20
Q
Motor neurons have long/short dendrites
A
short
21
Q
Motor neurons have long/short axons
A
long
22
Q
Where can cell bodies of motor neurons be found?
A
In the CNS
23
Q
Motor neurons have long axons which form part of what?
A
The PNS
24
Q
Neurons vary in size from which lengths?
A
Less than a millimetre to up to a metre long
25
True/False: All neurons share the same basic structure
True
26
What can be found in the cell body/soma of a neuron
The nucleus
27
What does the nucleus contain?
The genetic material of the cell
28
Dendrites are ______like structures
branch
29
Where do dendrites protrude from?
The cell body
30
What to dendrites do?
Carry nerve impulses from neighbouring neurons towards the cell body
31
What does a neuron's axon do?
Carry impulses away from the cell body down the length of the neuron
32
What is an axon covered in?
A fatty layer of myelin sheath
33
What does the fatty layer of myelin sheath covering an axon do?
Protects the axon and speeds up electrical transmission of the impulse
34
What would happen if the myelin sheath was continuous?
It would have the reverse effect and slow down the electrical impulse
35
True/False: The myelin sheath is segmented by gaps
True
36
What are the gaps segmenting the myelin sheath called?
Nodes of ranvier
37
What do nodes of Ranvier do?
Speed up the transmission of the impulse
38
How do nodes of Ranvier speed up the transmission of the impulse?
By forcing it to 'jump' across the gaps along the axon
39
What can be found at the end of the axon?
Terminal buttons
40
What do axon terminal buttons do?
Communicate with the next neuron in the chain across a gap known as the synapse
41
Each neuron is separated from the next by an extremely tiny gap called what?
The synapse
42
When a neuron is in a resting state the inside of the cell is positively/negatively charged compared to the outside
negatively
43
When a neuron is activated by a stimulus what happens to the inside of the cell?
It becomes positively charged for a split second
44
What does the inside of a neuron becoming positively charged for a split second cause?
An action potential to occur
45
What happens when an action potential occurs in a neuron?
It creates an electrical impulse that travels down the axon towards the end of the neuron
46
Neuron networks
Groups in which neurons communicate with each other
47
How are signals within neurons transmitted?
Electrically
48
How are signals between neurons transmitted?
Chemically across the synapse
49
What is the end of the neuron called?
Presynaptic terminal
50
What happens when an electrical impulse reaches the end of the neuron?
It triggers the release of neurotransmitter from tiny sacs called synaptic vescles
51
When an electrical impulse reaches the end of the neuron, it triggers the release of neurotransmitter from what?
Tiny sacs called synaptic vesicles
52
Neurotransmitters are chemicals that _______ across the _______ to...
diffuse, synapse, the next neuron in the chain
53
When a neurotransmitter crosses the synapse, where does it go?
It is taken up by a postsynaptic receptor site on the dendrites of the next neuron
54
Which part of neurons take signals to the synapse?
Axons
55
Which part of neurons take signals away from the synapse?
Dendrites
56
What happens at the postsynaptic receptor site on the dendrites of the next neuron?
The chemical message is converted back into an electrical impulse and the process of transmission begins again in another neuron
57
True/False: Direction of travel in neural networks is two-way
False, it can only be one-way
58
Neurotransmitters in neural networks are released from where when crossing the synpase?
The presynaptic neuron terminal
59
Where are neurotransmitters received after crossing the synapse?
The postsynaptic neuron at the receptor sites
60
How many types of neurotransmitter have been identified in the brain?
Several dozen
61
True/False: Some neurotransmitters have been identified in the spinal cord and some glands
True
62
True/False: Each neurotransmitter has its own specific molecular structure
True
63
How do neurotransmitters fit perfectly into a postsynaptic receptor site?
Each neurotransmitter has its own specific molecular structure, similar to a lock and key
64
Where can acetylcholine be found?
At each point where a motor neuron meets a muscle
65
Upon its release, what will acetylcholine cause muscles to do?
Contract
66
Neurotransmitters can have one of which two effects on the neighbouring neuron?
Excitatory or inhibitory
67
Serotonin causes excitation/inhibition in the receiving neuron
inhibition
68
The fact that serotonin causes inhibition in the receiving neuron results in what?
The neuron becoming more negatively charged and less likely to fire
69
True/False: Adrenaline is an element of the stress response which is strictly a hormone
False, it is both a hormone and a neurotransmitter
70
Adrenaline causes excitation/inhibition in the postsynaptic neuron
Excitation
71
The fact that adrenaline causes excitation in the postsynaptic neuron results in what?
The neuron becoming more positively charged and makes it more likely to fire
72
Whether a postsynaptic neuron fires is decided by which process?
Summation
73
Summation is when what happens to the excitatory and inhibitory influences?
They are summed
74
In summation, what happens if the net effect on the postsynaptic neuron is inhibitory?
The postsynaptic neuron is less likely to fire
75
In summation, what happens if the net effect on the postsynaptic neuron is excitatory?
The postsynaptic neuron is more likely to fire
76
What happens when the net effect of summation is excitatory?
The inside of the postsynaptic neuron momentarily becomes positively charged - creating an electrical impulse that travels down the neuron
77
What happens when the inside of the postsynaptic neuron momentarily becomes positively charged?
An electrical impulse is created and it travels down the neuron
78
The action potential of the postsynaptic neuron is only triggered if what?
The sum of the excitatory and inhibitory signals at any one time reaches the threshold
