Chapter 7 Nerve tissue - ahmu.edu.cn

Anhui Medical University


Chapter 7 Nerve tissue

Xue-mei Jia

[email protected]

Department of Histology and Embryology




Contents• 1. General characteristics• 2. Neurons• 3. Synapses• 4. Glial cells • 5. Nerve fibers• 6. Nerve endings



1. General Characteristics



• Nervous system

Central nervous system brain (CNS) spinal cord

Peripheral nervous system ganglia(PNS) nerves

nerve endings• Function --- integrating and

coordinating body activity

• Principal element --- nervous tissue



• what are the nervous tissues

consisted of ？



composition of nervous tissue

• nerve cells or neurons structural and functional unit .

• glias or neurogliassupporting, protecting and nourishing neurons.



nerve cells



glias

nerve cells



2. Neurons（1）Morphology

（2）Structure ★（3）Classification


Anhui Medical University(1)MorphologyCell body: spherical, pyramidal, ovoid or stellate Processes: --- dendrite: like branches of tree

--- axon: long thin cord-liked



(2) Structure① Cell body

(perinuclear cytoplasm) (perikaryon)

---Cell membrane excitable membrane receives stimuli

generates and transmits impulse.



---Nucleus large spherical pale-staining with a

prominent nucleolus,

Nucleus

nucleolus



---cytoplasm structural features

Nissl bodyLM: coarse or fine

basophilic particlesEM: RER（ Rough Endoplasmic Reticulum ）

free ribosomeFunction:

synthetize proteins

LM

EM



Neurofibril

LM: （in silver staining）thin thread-liked structure dark brown color form a network

EM: neurofilament microtubule

Function:serve as cytoskeletoninvolved in transportation of

substances

neurofibril

neurofilament

microtubule

LM

EM



• Neurofibrillary tangles ----one characteristic of Alzheimer‘s syndrome

normal photomicrographs pathological photomicrographs



② Dendriteone or more dendrites short and thick, more branchesdendritic spine on the surfacescontain Nissl bodies function : to receive

stimuli from other neurons and conduct it to the parent cell body

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③Axononly one axon / neuron usually long and thin with

uniform diameter, does not branch profuselysurface is smooththe axon is devoid of Nissl

bodiesfunction : generating or

conducting nerve impulseto other cells


Anhui Medical University• Axon structure

• axon hillock the beginning part of axon. The axon and axon hillock are devoid of Nissl bodies.

• axolemma（plasm membrane）

• axoplasm（cytoplasm）

• axon terminals ends in several terminal branches called axon terminals or buttons, which contain vesicles with neurotransmitters in them.

axon hillock



dendrites and axons

Dendrites Axons

Amount

Shape

Surface

Structure

Function

Can you fill in ?

Review



Nucleus

cell body cell membrane nucleus cytoplasm Nissl body

neurofibril

dendrite axon

neuron

Review

silver staining

HE staining



（3） Classification

---According to number of processes---According to the function


Anhui Medical University---According to number of processes multipolar neurons which have more than two

cell processes, one process being the axon and the others dendrites

bipolar neurons with one dendrite and one axon

pseudounipolar neuronssingle process, soon divides into two in a T-shape, with one branch extending to a peripheral ending and the other towardthe CNS.


Anhui Medical University---According to the functionsensory neurons

(afferent neurons): are involved in the receptionof sensory stimuli from the environment or withinthe body.motor neurons

(efferent neurons):control effector organs. interneurons:

establish relationships among other neurons, forming complex functional network.



How to form the neural network ？



3. Synapses（1）Definition ★（2）Classification （3）Chemical synapses ★


Anhui Medical University（1）Definition

synapses are sites of functional contact between neurons or between neurons and other effector cells,

where the nerve impulses are transmittedfrom one neuron to its target



（2）Classification

• Electrical synapse: permit direct flow of electrical current between two neurons (gap junction).

• Chemical synapse: taking chemical mediator (neurotransmitter) as communicating medium



Electrical synapse

This type of synapse transmit ionic signals through gap junctions that cross the pre- and postsynaptic membranes, thereby conducting neuronal signals directly.

Chapter 7 Nerve tissue - ahmu.edu.cn

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