nervous tissue online module W5 Flashcards
1
Q
nervous tissue exists as either part of the …..nervous system or the …..nervous system
A
central
peripheral
2
Q
how are cells distributed within the nervous tissue
A
cells (neurons) are scattered with only limited contact at the extremities
3
Q
cells of nervous tissue are characterized by having many cellular processes (……… ………..)
A
cytoplasmic extensions
4
Q
what exists between nervous tissue cells that allows signals to pass from cell to cell
A
highly specialized contact points (synapses)
5
Q
nervous tissue can have different characteristic depending on…
A
where it it, CNS or PNS
6
Q
what makes up the central nervous system (2)
A
brain and spinal chord
7
Q
what makes up the peripheral nervous system (3)
A
nerves
sensory receptors
ganglia
8
Q
in the CNS are cells surrounded by ECM
A
virtually no, CNS nervous tissue is highly specialised, with scattered cells and the space between cells is taken up by cellular processes of neurons and supporting cells
9
Q
are neurons excitable cells
A
yes
10
Q
how do neurons transmit signals from cell to cell
A
action potential is transmitted by reversing the polarity of the cell membrane
11
Q
what is ganglia
A
an accumulation o nerve cellbodies
12
Q
what are the two cells found in nervous system
A
neurons
glial cells
13
Q
what are the two cells found in nervous system
A
neurons
glial cells
14
Q
types of glial cells found in the CNS (4)
A
microglia
oigodendrocytes
astrocytes
ependymal
15
Q
types of glial cells found in PNS
A
satellite cells
schwann cells
16
Q
glial cells are …..cells
A
supporting
17
Q
satelite cells are only found in …
A
gnaglia
18
Q
schwann cells are found in …(2)
A
nerves and ganglia`
19
Q
circular area of neuron is called …….or ……
and this is where the… and most of the… is
A
cell body
soma
cytoplasm and nucleus
20
Q
what is another name for a multipolar neuron
A
motor neuron
21
Q
do neurons have large or small nuclei
A
large
22
Q
the nucleus of a neuron is highly…heterochromatic/euchromatic?
A
euchromatic
23
Q
why is the neuron highly euchromatic
A
it produces alot of protein for use within the cell and for exportin the form of neurotransmitters
24
Q
protein from a neuron is exported in the form of…
A
neurotransmittersneurotansmitters
25
neurons have a very prominent/unprominent nucleolus
prominent
26
what are nisil bodies
accumilation of RER and free ribosomes in the nucleus of a neuron
27
how long can neurons be
up to 1 meter
28
free ribosomes produce proteins that are likley to be used within / exported from the cell?
used within
29
rER produces proteins that are likely to be used within/exported from the cell?
exported
30
what are axon terminals
axon terminals often synapse onto dendrites
31
why do axons often synapse onto dendrites
in order to increase surface are to recieve information
32
what is an axon
a long thin cytoplasmic process
33
where is the soma located
| where does the axon go
soma is found in the CNS and the axon runs out into the PNS
34
what i found at the end of an exon (opposite to the soma) (two names)
axon terminals or axon boutons
35
what are dendrites
cytoplasmic processes
36
what is the job of dendrites
to recieve signals
37
what happens at the axon boutons or axon terminals
synapses occur
| neurotransmitters are released into other cells (either another neuron or another cell)
38
what are axons sometimes covered in
myelin sheaths
39
what are myelin sheaths
cellular wrappings of cells
40
what are myelin sheaths made out of in the CNS
oligodendocytes
41
what are myelin sheaths made out of in the PNS
schwanns
42
what is the axon hillock
the junction between the axon and the soma
43
why is the axon hillock important
neuron is receiving lots of signals from dendrocytes, and these signals are different - some of these signals are carrying information to produce action potentials and other signals are saying dont produce action potential. the decision making process of whether to produce or not produce action potential is made in the axon hillock (based on what signal is more abundant)
44
what are the four neuronal types
multipolar neuron
bipolar neuron
unipolar neuron
axoaxonic neuron or interneuron
45
what are the two sensory neurons
unipolar and bipolar neurons
46
what is the one motorneuron
mulipolar neuron
47
what senses is the biipolar neuron in charge of
vision taste smell and hearings
48
what is the functional difference between (unipolar and bipolar neurons ) and multipolar neurons
unipolar and bipolar neurons: bringing information from the periphery back into the CNS
mulipolar neurons: run information from the CNS into the periphery
49
what organs are the bipolar neurons found in
organs in charge of special sense (eg. vision smell hearing and taste)
50
what senses are the unipolar neurons associated with
pain- touch, tmeperature, vibration, stretch
51
interneurons /axoaxonic neurons exist in which nervous system?
CNS
52
what is the role of axoaxonic neurons /interneurons
as intermediates between neurons
53
where are the two places that neural bodies exist
in the CNS (spinal cord, brain)
in accumulations of cell bodies in the PNS called ganglia
54
what is ganglia
accumulations of neural bodies in the PNS
55
what produces myelin in the CNS
oligodenrocytes
56
main property of myelin
phospholipid rich
57
what is a node of ranvier
the space between myelin sheaths
| nodes of ranvier have veltage gated ion channels that accumulate on the axon cell membrane
58
what is the main role of myelin - explain
myelin acts as an insulator and allows and action potential to jump between nodes
59
what is saltatory conduction?
spend up conduction by the help of nodes of ranvier that allow action potential to jump from node to node
60
what is special about oligodendrocytes
they can myelinatemultiple axons at once ( or the same axon multiple times)
61
how are oligodendrocytes able to myelinate multiple axons at once (or one axon multiple times)
via long cytoplasmic processes that wrap around the axons
62
in which nervous system do shwans cells myelinate axons
PNS
63
in which nervous sytem do oligodendrocytes myelinate axons
peripheral nervous system
64
what is different about how shwann cells myelinate in comparison to oligodendrocytes
shwann cells can only myelinate one part of the axon but multiple shwa cells can myelinate the one axon
65
one axon may have up to ...... shwann cells
10 000
66
describe the difference between myelinated and unmyelinated axons
unmyelinated axons are grouped together by shwann cells
| unmyelinated axons tend to be smaller in diameter and conduct impulses at a slower rate
67
what cells envelop unmyelinated axons
shwann cells
68
what kind of ion channels line the post synaptic membrane
ligand gated ion channels that respond to the neurotransmitters
69
explian the process of synaptic neurotransmition
action potential travels down the axon and dwom the axon terminal which initiates voltage gated calcium ion channels to open, allowing clacium to flow into the axon terminal
the calcium prompts the synaptic vesicles to fuse with the presynaptic membrane and release the neurotransmitters into the synaptic clefts
the neurotransmitters bind to the ligand receptors on the ligand gated sodium ion channels which causes a conformational change to these channels which allows sodium ions to flow inside.
this causes the adjacent voltage gated sodium ion channels to open and their adjacent ones to open and so on etc.
allowing the action potential to be conducted and passed along the cell
70
once neurotransmitters are released into the synaptic cleft and bind to ligand gated ion channels what happens to them
list the 3 main ways that neurotransmitters are disposed of
they are released by the ligand receptors
then disposed of by:
reuptake by the axon terminal
uptake by surrounding glial cells
release of enxymes that degrade the neurotransmitters
71
what is the name for dendritic offshoots
dendritic spines
72
what is the purpose of dendritic spines
to increase surface are for information uptake
73
nervous tissue in the CNS is made up of two types of matter what are they
grey matter and white mater
74
why is white matter white
because it is made up of tacks of myelinated axons
75
what is grey matter composed of (broad) (1)
ie. neuropil
76
what is neuropil
neurons and everything that is in between them
77
what is neuropil and therefore grey matter composed of (5)
```
neurons and everything that surrounds them
dendrites
glial cells
axons
cytoplasmic processes
```
78
arrangement of white and grey matter in spinal cord
white matter on outside grey on inside
79
arrangement of white and grey matter in brain
grey matter on outside
| grey matter on inside
80
the spinal chord has an ........and a ........ surface
anterior
| posterior
81
which surface of the spinal chord has a large depression
the anterior surface
82
what is the name of the large depression in the white matter of the spinal chord on the anterior surface called
medial anterior fissure
83
on that surface do the butterfly's wings touch the surface
posterior or dorsal
84
where are synapses found (specific and broad)
contact pints between axon terminal bountons and other cells or another neuron
in the neuropil
85
synapses can only properly be studied under the EM or LM ?
under the EM
86
what is white matter composed of (3)
tracks of myleinated axons
blood vessels
glial cells
87
what glial cells are found in white matetr (3)
oilgodendrocytes, astrocytes, microglial cells
88
what are the most numerous and largest glial cells
astrocytes
89
what is the physical structure of an astrocyte
consist of a number of long cytoplasmic processs that make them look like stars and at the end form feet which associate with blood vessels
90
what is the purpose of an astrocyte's long cytoplasmic processes
they extend into the surrounding tissue of the brain and the spinal chord and associate with neurons and blood vessels (blood brain barrier)
91
what is the blood brain barrier
the way in which the body protects the brain from invading microorganisms and toxins
the astrocytes 'feet' encircle endothelial cells and act as a barrier between them and neurons
92
how do astrocytes act as intermediates between blood vessels and neurons
they have gap junctions through which they can provide structural and nutritional support for neurons
93
what are the primary functions of astrocytes (4)
they acts as intermediates betwen blood vessels adn neurons
they control the environment of the CNS by removing excess ions and neurotransmitters
they form scar tissue
regeneration in the nervous system
94
what is the name of the scar tissue that if formed by astrocytes
gliocyis
95
roles of microglial cells in the CNS
they act as resident mecrophages and are pat of the innate immune system in the CNS - they are able to phagocytose anycellular debris, damaged cells or invading organisms
96
what is the purpose of ependyme cells in the CNS
they line the central canla f the spinal chord and passages within the brain that contain CSF - ependyme cells help circulate the CSF and connect to glial cells in the CNS
97
what do ependyme cells line
central canal of spinal chord , and passages within the brain that contain CSF
98
what are nerves made out of (3) what are they not made out of (1)
axons
shwann cells
CT
not made out of comas
99
what are the levels of organisation of CT in a nerve small-->large
andoneurium
perineurium
epineurium
100
what is the endoneurium and what does it line
loose CT
| lines individual axons (encapsulating both the axon and the shwann cells that myelinate them)
101
what is the perineurium and what does it line
dense irreg CT lines fasicales (which are clusterns of axons)
102
what is the epineurium
dense irreg CT that lines the outside of a nerve
103
what part of the spinal chord contains some of efferent fibres
ventral root (grey)
