Cells of the nervous system Flashcards
(93 cards)
1
Q
What are the 2 main cells of the nervous system?
A
- Neurones
- Glia
2
Q
What are glia?
A
Supporting cells found around neurones
3
Q
What does the Nissl stain do?
A
- Distinguishes between neurones and glia by highlighting the endoplasmic reticulum and free ribosomes in the cell bodies of neurones
- Allows visualisation of variation in size density, distribution of neurones
4
Q
Which part of cells does the Nissl stain highlight?
A
Nucleic acids (rRNA in nucleolus etc.)
5
Q
What is the soma?
A
Cell body of neurones
6
Q
Which organelle is particularly abundant in cell bodies of neurones?
A
Mitochondria
7
Q
What does the Golgi stain do?
A
- Highlights a random small percentage of neurones in the sample
- Shows dendrites
8
Q
What is the Golgi stain made of?
A
Silver chromate
9
Q
What are the 4 major compartments of the neuron?
A
- Cell body
- Dendrites
- Axons
- Presynaptic terminal
10
Q
What is the perikaryon?
A
Another name for the cell body/soma of neurones
11
Q
What are neurites?
A
- A process coming off a neuron
- Dendrite or axon
12
Q
What are the 3 main elements of the cytoskeleton of neurones?
A
- Microtubules
- Microfilaments
- Neurofilaments
13
Q
What are microtubules?
A
- Run longitudinally down neurites
- Made of hollow tubes of tubulin
14
Q
What are microfilaments?
A
- Polymers of actin
- Randomly orientated and associated with the membrane
15
Q
What are microfilaments made of?
A
Actin
16
Q
What are microtubules made of?
A
Tubulin
17
Q
What are neurofilaments made of?
A
Long protein molecules which have been wound together
18
Q
What are the 4 areas of the axon?
A
- Axon hillock
- Axon initial segment
- Axon collaterals
- Axon terminal/terminal bouton
19
Q
What are axon collaterals?
A
Side branches of axons
20
Q
What is absent in the axon that is in the cell bodies?
A
- Rough ER
- Free ribosomes
21
Q
What is immunohistochemistry?
A
- Method to identify the locations of specific proteins
- Specific primary antibodies which bind to the protein of interest
- Fluorescent secondary antibodies which bind to the primary antibody
22
Q
What are the specialisations of the presynaptic terminals?
A
- No microtubules
- Many mitochondria
- Synaptic vesicles
23
Q
What are boutons en passent?
A
A presynaptic terminal in the middle of an axon
24
Q
What is axoplasmic transport?
A
Transport of molecules up and down axons
25
Which protein does anterograde transport down the axon?
Kinesin
26
Which protein does retrograde transport down the axon?
Dynein
27
How do kinesin and dynein transport molecules along axons?
"Walk" along the microtubules
28
What is the function of dendrites?
Receive information from other neurones
29
What are dendritic spines?
Small protrusions of the dendrite membrane
30
What is the function of dendritic spines? (3)
- Isolate chemical reactions
- Axons can synapse onto them
- Very plastic depending on activity of the dendrite
31
What are the classifications of neurons based on number of neurites? (4)
- Unipolar
- Pseudounipolar
- Bipolar
- Multipolar
32
What is a unipolar neuron?
One neurite coming off its cell body
33
What is a pseudounipolar neuron?
- One neurite coming off the cell body which splits into two
| - Peripheral process is partly axon
34
What is a bipolar neuron?
- 2 neurites coming off the soma
| - One side is dendritic, other is axon
35
What is a multipolar neuron?
- Multiple neurites coming off the soma
| - One axon and multiple branching dendritic portions
36
What is a ganglion?
Group of neuronal cell bodies found in the periphery
37
What kind of neurons are dorsal root ganglion neurons? (2)
- Sensory neurons
| - Pseudounipolar neurons
38
What classification are dorsal root ganglion neurons?
Pseudounipolar
39
What is an example of a pseudounipolar neuron?
Dorsal root ganglion neuron
40
How are dorsal root ganglion neurons arranged?
- Cell body sits in the dorsal root ganglion
- One side projects to the periphery and dendritic portion picks up signals
- Other side projects into the dorsal horn of the spinal cord
41
What does the acronym DAVE mean?
Dorsal Afferent Ventral Efferent
(Afferent neurons enter the spinal cord dorsally carrying signals from the body to the brain, efferent neurons exit the spinal cord ventrally carrying signals from the brain to the body)
42
What are the features of pseudounipolar neurons? (3)
- Process projecting into the periphery is part axon
- Small dendritic portion for receiving synaptic input
- Reliable relay of information due to not much integration
43
What is an example of a bipolar neuron?
Retinal bipolar cells
| Between rods/cones and retinal ganglion cells
44
What are the features of bipolar neurons? (2)
- Small area for receiving synaptic input
| - Reliable relay of information
45
What are the features of multipolar neurons? (2)
- Large area for receiving synaptic input
| - High levels of convergence
46
Which class of neurons is the most common in the brain?
Multipolar neurons
47
What is an example of a multipolar neuron?
Purkinje cell
48
What are the classifications of neurons based on dendritic geometry? (2)
- Pyramidal
| - Stellate
49
What are the features of pyramidal neurons? (2)
- Pyramid shaped soma
| - Apical and basal dendritic tress
50
Where are pyramidal neurons found in the brain? (2)
- Neocortex
| - Hippocampus
51
What are the features of stellate neurons? (1)
Star shaped dendritic arbour
52
Where are stellate neurons found in the brain?
Neocortex
53
Are sensory neurons afferent or efferent?
Afferent
54
Are motor neurons afferent or efferent?
Efferent
55
How are motor neurons arranged?
Project from the ventral horn into the periphery
56
What part of the nervous system contains interneurons?
CNS
57
What is the largest class of neurons?
Interneurons
58
What are the 2 classes of interneurons?
- Relay/projection neurons
| - Local interneurons
59
What do relay/projection neurons do?
Connect brain regions
60
What do local interneurons do?
- Process information in local circuits
| - Short axons
61
What is the main difference between neurons and glia?
Glia can proliferate throughout life but neurons don't regenerate
62
What are the glial cells in the CNS? (3)
- Astrocytes
- Oligodendrocytes
- Microglia
63
What are the glial cells in the PNS? (3)
- Satellite cells
- Schwann cells
- Macrophages
64
What are the glial cells in the ENS? (1)
Enteric glia
65
Which glial cells in the CNS have a homeostatic function?
Astrocytes
66
Which glial cells in the PNS have a homeostatic function?
Satellite cells
67
Which glial cells in the ENS have a homeostatic function?
Enteric glia
68
Which glial cells have a homeostatic function? (3)
- Astrocytes
- Satellite cells
- Enteric glia
69
Which glial cells in the CNS are myelinating?
Oligodendrocytes
70
Which glial cells in the PNS are myelinating?
Schwann cells
71
Which glial cells are myelinating? (2)
- Oligodendrocytes
| - Schwann cells
72
What are astrocytes?
Glial cells in the CNS with homeostatic functions
73
What are satellite cells?
Glial cells in the PNS with homeostatic functions
74
What are enteric glia?
Glial cells in the ENS with homeostatic functions
75
What are oligodendrocytes?
Glial cells in the CNS that are myelinating
76
What are Schwann cells?
Glial cells in the PNS that are myelinating and phagocytic
77
Which glial cells in the CNS are phagocytic?
Microglia
78
Which glial cells in the PNS are phagocytic?
Schwann cells and macrophages
79
Which glial cells are phagocytic? (3)
- Microglia
- Macrophages
- Schwann cells
80
What are microglia?
Glial cells in the CNS that are phagocytic
81
What are macrophages?
Glial cells in the PNS that are phagocytic
82
What are ependymal cells?
Astrocytes which line the ventricles and central canal (CSF)
83
What are the features of astrocytes? (3)
- Store glycogen to supply energy in the form of lactate to the neurons
- Endfeet around capillaries take up glucose and keep vasculature separate from neurons
- Modifies synapses
84
What do astrocytes do at synapses?
- Terminates neurotransmitter activity
| - Can recycle neurotransmitter back into presynaptic terminal
85
What is a tripartite synapse?
Synapse involving 3 different cells
86
What proportion of the CNS glial cells are microglia?
15%
87
Which glial cells are involved in synaptic pruning?
Microglia
88
How can microglia have detrimental effects?
Can play a role in neurodegenerative diseases
89
What is the main difference between oligodendrocytes and Schwann cells?
Oligodendrocytes can have many processes from one cell body to myelin sheath whereas Schwann cells only provides one myelin segment to a single axon
90
How do myelin sheaths form?
- A process from a cell wraps around the axon many times
| - Cytoplasm is squeezed out by compaction
91
What is the function of myelin?
Insulating and creates nodes of Ranvier so action potentials can jump down the axon (saltatory conduction)
92
What is a difference between CNS and PNS axons?
PNS axons can regenerate after injury but CNS axons can't
93
How are myelin sheaths maintained?
Stay connected to the Schwann cell/oligodendrocyte for nourishment
