Transcript Nervous Tissue

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Nervous Tissue
Li DongMei

Central nervous system (CNS)

Peripheral nervous system (PNS)
Composition of nerve tissue

Two types of cells
---Components:
 nerve cell: neuron
 Glial cell: neuroglial
---Function:
 Neurons : receive the stimulation, conduct
the nerve impulse, transmit the impulse
 Glial cell: support, protect and insulate,
nourish neurons
1. Neuron
1. Neuron
Billions neurons and more glial cells
form human nervous system.
 It is the structural and functional unit of
the nervous tissue.
 Neuron consists of cell body(soma),
dendrite and axon.
 Neuron is a cell that receive the
stimulation ,conduct the nerve impulse
and transmit the impulse.

Cell body
Dendrite
processes
Axon
① Cell body of neuron (soma)
① Cell body of neuron (soma)
① soma
Nissl body(tigroid body)
Location: located in cytoplasma and large dendrites
LM: basophilic spot-liked or granule-liked structure
EM: parallelly-arranged RER and free ribosome
Function: synthesis of proteins, enzymes and
neurotransmitters
motor
neuron from
Spinal cord
Spinal
ganglion
Neurofibril:
Location: are abundant in
cytoplasma and cell processes.
LM: in silver impregnation
methods(silver
preparation),
there are many thread-liked dark
brown color structure to form a
network.
EM: neurofilament, microtubule
Function:
supporting(cytoskeleton),
involving
in
intracellular
transportation
Exercises
1. Somas possess which one of the following structures?
(A) Microtubules
(B) Neurofilaments
(C) Nissl bodies
(D) Mitochondria
(E) All of the above
2. Nissl bodies are composed of
(A) synaptic vesicles and acetylcholine
(B) Free ribosomes and rough endoplasmic reticulum
(C) lipoprotein and melanin
(D) neurofilaments and microtubules
(E) smooth endoplasmic reticulum and mitochondria
Answers and Explanations
1-E. Somas possess microtubules, neurofilaments, Nissl bodies, and mitochondria.
2-B. Nissl bodies are large granular basophilic bodies composed of free ribosomes and rough
endoplasmic reticulum. They are found only in neurons(in the soma cytoplasm).
② Dendrites
No Golgi complex, other contents
are similar to the cell body.
Increase the receptor surface area
of a neuron.
To receive stimuli from other
neurons or from the external
environment.
③ Axon



A Long Fiber that carries
impulses away from the
cell body.
Each neuron has only
one axon.
The Axon Ends in a
series of small swellings
called axon terminals
Exercises
The axon hillock contains
(A) rough endoplasmic reticulum
(B) ribosomes
(C) microtubules
(D) Golgi complex
(E) synaptic vesicles
Answer and Explanation
C. The axon hillock contains microtubules, which are arranged in bundles.
2. Synapses
2. Synapses

Specialized junctions between neurons,
between axons and effector cells
Classification
Electrical synapses
gap junctions
Chemical synapses
taking neurotransmitter as
communicating medium
Chemical
synapse
Synaptic transmission
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



Calcium gates open
Synaptic vesicles release neurotransmitter
Neurotransmitter binds with postsynaptic
receptors
The postsynaptic membrane is excited or
inhibited
The neurotransmitter is degraded and recycled.
Exercises
Synaptic vesicles possess which of the following characteristic?
(A) Manufacture neurotransmitter
(B) Enter the synaptic cleft
(C) Become incorpotated into the presynaptic membrane
(D) Become incorporated into the postsynaptic membrane
Answer and Explanation
C. Synaptic vesicles release neurotransmitter into the synaptic cleft by exocytosis.
In this process, the vesicle membrane is incorporated into the presynaptic membrane.
Although these vesicles contain neurotransmitter, they do not manufacture it.
3. Glial cell(neuroglia)
3. Glial cell(neuroglia)
3. Glial cell(neuroglia)
Schwann cell
envelop the axon end to end to form
myelin-sheath in PNS and
Satellite cell (capsular cell)
one layer of flattened or cuboidal cell,
with round, ovoid and dark N
surrounding the Neuron in ganglion
4.Nerve fiber and Nerve
Nerve fiber
definition: axon enveloped by neuroglial
cells
classification: according to myelin-sheath
 myelinated nerve fiber
 unmyelinated nerve fiber
myelinated nerve fiber in CNS
---structure:
 similar to in PNS
 myelin-sheath formed by flattened
ending of oligodendrocyte’s processes
 one oligodendrocyte can envelop many
axons
 no incisure and basement membrane

Nerve
5. Nerve Ending