NERVOUS TISSUE Flashcards
(132 cards)
1
Q
nervous tissue is formed by
A
a network of many billion nerve cell or neuron
2
Q
nerve cells ( neurons ), all assisted by many more supporting cells called
A
glial cells .
3
Q
all support from any other organ in other tissue except brain and nervous is called
A
Connective tissue
4
Q
glial cells are also
A
nerve cells
5
Q
Each neuron has hundreds of interconnections with other neurons, forming
A
a very complex system for processing information and generating responses
6
Q
Anatomically, the general organization of the nervous system has two major divisions:
A
CNS and PNS
7
Q
CNS is consist of
A
brain and spinal chord
8
Q
Peripheral nervous system (PNS) , composed of
A
the cranial, spinal, and peripheral nerves conducting impulses to and from the CNS (sensory and motor nerves, respectively) and ganglia
9
Q
that are small groups of nerve cells outside the CNS.
A
ganglia
10
Q
enters the CNS
A
sensory nerve
11
Q
away from CNS
A
motor nerve
12
Q
PNS almost made up completely of
A
nerve fibers/ axons
13
Q
axons are synonymous to
A
nerves
14
Q
nerve fibers
A
sensory nerve and motor nerve
15
Q
the way our body does homeostasis
A
hormonal and nervous control
16
Q
how we respond to the action to maintain homeostasis
A
consciously and unconsciously
17
Q
Neurons respond to environmental changes ( stimuli ) by
A
altering the ionic gradient that exists across their plasma membranes
18
Q
All cells maintain such a gradient, also called an
A
electrical potential, but cells that can rapidly change this potential in response to stimuli (eg, neurons, muscle cells, some gland cells) are said to be excitable or irritable.
19
Q
Neurons react promptly to stimuli with a
A
reversal of the ionic gradient ( membrane depolarization ) that generally spreads from the place that received the stimulus and is propagated across the neuron’s entire plasma membrane. This propagation, called the action potential , the depolarization wave , or the nerve impulse , is capable of traveling long distances along neuronal processes, transmitting such signals to other neurons, muscles, and glands.
20
Q
action potential
A
nerve impulse
21
Q
cell body
A
pericharia
22
Q
Neurulation in the early embryo.
A
- Neural folds and neural groove form
from the neural plate.
2.Neural folds elevate and approach one
another.
- As neural folds prepare to fuse and form
the neural tube and dorsal epidermis,
neural crest cells loosen and become
mesenchymal. - The mass of neural crest cells initially
lies atop the newly formed neural tube.
23
Q
neural tube will give rise to
A
CNS
24
Q
neural crest will give rise to
A
PNS
25
Functioning part of both CNS and PNS
Neuron
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3 major parts of neurons
Cell body/perikaryon
Dendrites
axon
27
Contains nucleus and most of cell organelles and serve are synthetic or trophic center for entire neurons
Cell body/perikaryon
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most cell bodies can be seen in CNS but sometimes can be seen in PNS as
ganglia
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numerous elongated processes extending from perikaryon and specialize to receive stimui from other neurons from site called
Dendrites
synapses
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single long process ending at synapses specialize to generate and conduct nerve impulse to other cells
axon
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neurons can be classified according to no. of processes extending from cell bodies
miltipolar neuron
| unipolar neuron
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multipolar neuron
have one axon and 2 or more dendrites
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bipolar neuron
1 dendrite 1 axon
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unipolar neuron/pseudounipolar neuron
have a single process that bifurcates close to the perikaryon, with the longer branch extending to a peripheral ending and the other toward the CNS.
35
Anaxonic neurons
, with many dendrites but no true
axon, do not produce action potentials, but regulate
electrical changes of adjacent neurons.
36
most neurons are
multipolar
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Bipolar neurons are found in the
retina
olfactory mucosa the (inner ear)
cochlear and vestibular ganglia,
where they serve the senses of sight, smell, and balance, respectively.
38
Pseudounipolar neurons are found in
the spinal ganglia (the sensory ganglia found with the spinal nerves) and in most cranial ganglia.
39
Nervous components can also be subdivided functionally
Sensory neurons
Motor neurons
Somatic motor nerves
autonomic motor nerves
40
Sensory neurons are
afferent and receive stimuli from the receptors throughout the body
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Motor neurons are
efferent, sending impulses to effector organs such as muscle fibers and glands
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Somatic motor nerves are under
voluntary control and typically innervate most skeletal muscle;
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autonomic motor nerves control the
“involuntary” activities of glands, cardiac muscle, and most smooth muscle.
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not all skeletal mucle are under
voluntary control
45
Interneurons
establish relationships among other neurons, forming complex functional networks or circuits
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in CNS, most neuronal perikarya occurs in ___, with axons concentrated in ___
grey matter
| white matter
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in PNS, cell bodies are found in
ganglia and in some regions like olfactory mucosa
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PNS made up of
axons are bundled in nerves
49
Parkinson disease is
a slowly progressing disorder affecting muscular activity characterized by tremors, reduced activity of the facial muscles, loss of balance, and postural stiffness. It is caused by gradual loss by apoptosis of dopamine-producing neurons whose cell bodies lie within the nuclei of the CNS substantia nigra. Parkinson disease is treated with l-dopa (L-3,4-dihydroxyphenylalanine), a precursor of dopamine which augments the declining production of this neurotransmitter.
50
The cell body is the
neuronal region that contains the nucleus and surrounding cytoplasm, exclusive of the cell processes
51
finely dispresed, reflecting intense synthetic activity
chromatin
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cytoplasm of perikaryon
concentrated RER and other polysomes appear as clumps of basophilic material called chromatophilic substance (or Nissl substance, Nissl bodies
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purplish
basophilic materials
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usually short and devided to 3 branches
dendrites
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usually covered with synapses and are the principal signal reception and processing sites on neurons
dendrites
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Most neurons have only one axon
, a fine cylindrical process that varies in length and diameter according to the type of neuron. Axons are usually very long processes
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Axons originate from a pyramid-
| shaped region of the perikaryon called the
axon hillock
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The plasma membrane of the axon is often called
the axolemma and its contents are known as axoplasm.
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distal end of an axon forms a
terminal arborization
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and axons of interneurons and some motor neurons have branches called
COLLATERALS that end at synapses influencing the activity of many other neurons
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Each branch ends with a dilation called a
terminal bouton
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contacts another neuron or non-nerve cell at a synapse to initiate an impulse in that cell.
terminal bouton
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has faster electrical impulse/depolarization
unmyelinated axon
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soltatory conductions
nerve impulse jump
| only inc
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unmyelinated axon mostly found in
SPINAL CORD.
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sites where nerve impulse are transmitted from one neuron to another/ from neurons and other effector cells
synapse
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structure of synapse is
unidirectional
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nervous tissue communicates with our body via
electro chemical signal
electrical signal
69
neuron to neuron communication
electrical-chemical-electrical
70
it converts electrical signal 9nerve impulse( from pre synaptic cell into chemical signal that effects the post synaptic cells.
synapse
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most synapses release
neurotransmitter
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small molecules that bind specific receptor proteins to either open or close ion channels or initiate second messenger cascade.
neurotransmitter
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space bet. presynaptic to postsynaptic
synaptic cleft
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synaptic vescicle holds ACH.
bababa si synaptic neurons, open calcium channel
the calcium will go inside
it will initiate vescicle to fusse with pre synaptic cleftvia exocytosis=
ACH
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ACH will be free floating on
synaptic cleft
ang received by post synaptic cleft (ACH receptors)
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Components of synapse
```
Presynaptic axon (terminal bouton)
Postsynaptic axon
```
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Presynaptic axon (terminal bouton)
wheere neurotransmitter is released by exocytosis
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Postsynaptic axon
receptor for neurotransmitter and ion channels and other mechanism to initiate nerve impulse
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calcium in blood
PTH
released by osteoclast
80
Calcium in bone
Calcitonin
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pag na receive na ni post si neurotransmitter
either excitatory or inhibitory effect of the post synaptic
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if an axon forms a synapse with a cell body it is called
axosomatic synapse
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axon with a dendrite
axodendritic
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axon with another axon for modulation of electrical siignal
axoaxonic
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type of connective tissue that supports CNS
glial cells
86
supports neuronal survival and activities and ten times more abundant in neuron
Glial cells
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6 types of Glial cells
```
Oligodendrocyte
Shwann cells (neurolemocyte)
satellite cells
Epindymal cells
Microglia
Astrocytes
```
88
Oligodendrocyte
produce mylein seath
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provide electrical insulation for neurons in CNS
Oligodendrocyte
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predominant glial cells in CNS of white matter
Oligodendrocyte
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why white matter is white
lipid concentration in the wrapped membrane seath
-axon na may myeline seath
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have large number of radiating process and also unique in cns
astrocytes
93
most numerous glial cells of CNS and diverse structurally and functionally
astrocytes
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types of astrocytes
fibrous astrocytes
| protoplasmic astrocytes
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typical in white matter and have relatively few long processes
fibrous astrocytes
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predominant in grey matter and have many shorter branch processes
protoplasmic astrocytes
97
largest processes of all astrocytes are reinforced with bundles of intermediate filaments called
Glial fibrilary acid proteins/GFAP
| serves as unique marker for astrocytes, the most common source of brain tumor
98
Functions associated with various astrocytes
- Regulates extracellular concentrations around neurons
- Guides and physically supports movement of locations of differentiating neurons in the developing CNS.
- extending processes and expanded perivascular feet that cover endothelial cells and contribute to BBB.
- Serves as a gate sp that it will limit substances from the blood to go to the brain
- Adds extra layer of filtrarion
- Form a barrier layer expanded process called GLIAL LIMITING MEMBRANE
99
Astrocytes communicate directly via
Gap junctions
100
glial cells in CNS
Oligo
astro
epindymal
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Ependymal cells
columnar/cuboidal cells that lines the ventricles of the brain and centra; canal of spinal chord
102
in some CNS location apical ends of Ependymal cells have
-cilia
facilitate movement of CSF
-long microvilli
for absorption
103
Epindymal cells are joint apically by
junctional complexes like of epithelial
104
Microglial
short cells with small irregular processes evenly distributed throughout grey and white matter
105
secrete a number of immunoregulatory cytokenes and constituate major mechanism of immune defense in CNS
Microglial cells
106
macrophages of CNS
Microglia
107
Microglia came from
blood circulating monocytes
108
Shwann cells
(neurolemocyte)
109
glial cells found in PNS
Shwann cells
from neural crest
110
serve as myelinating cells of PNS and support cells of peripheral neurons
Shwann cells
111
Satellite cells
SUPPORT GANGLIA
forms and intimate covering layer over the large neuronal cell body in ganglia of PNS
112
Electrically insulate PNS cell bodies
Satellite cells
113
regulates nutrients and waste exchange for cell bodies in ganglia
Satellite cells
114
Major regions of CNS
Cerebrum, cerebellum, spinal chord
115
covering of CNS
meninges
116
membrane of Connective tissue located bet. bone and nervous tissue of CNS.
meninges
117
meninges layers
dura matter -taas
arachnoid -gitna
pia matter
118
where can we see the blood vessel
subarachnoid space
119
where subdural hematoma happen
subarachnoid space
120
tas ng arachnoid
subdural space
121
A functional barrier that allows much tighter control than that in most tissue.
Blood brain barrier
122
main structure of BBB
Capiliary endothelium
where cells are tightly sealed together by occluding junction
123
Choroid plexus
consist of highly specialized tissue with elaborate folds and many villi
124
Choroid plexus
consist of highly specialized tissue with elaborate folds and many villi
125
remove water from blood and release it as CSF
Choroid plexus
126
nerves are also
axons
127
nerves
bundles of nerve fibers (axon) sorrounded by swann cells and CT.
128
peripheral nerve
consist of axon from motor neurons
129
only large myelinated axons have
myeline seaths adn nodes of ranvier
130
endonerium
sorrounds shwann cells
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group of axons sorrounded by
perinurium
132
sorround perinurium is
epinurium
