Nervous Tissue Nervous Tissue

Li DongMei

Website ： m-learning.zju.edu.cn

Central nervous system (CNS)Central nervous system (CNS)

Peripheral nervous system (PNS)Peripheral nervous system (PNS)

Composition of nerve tissueComposition of nerve tissue Two types of cellsTwo types of cells

---Components: ---Components: nerve cell: neuronnerve cell: neuron Glial cell: neuroglialGlial cell: neuroglial---Function: ---Function: Neurons : receive the stimulation, Neurons : receive the stimulation,

conduct the nerve impulse, conduct the nerve impulse, transmit the the impulse

Glial cell: support, protect and insulate, Glial cell: support, protect and insulate, nourish neuronsnourish neurons

1. Neuron

1. Neuron1. Neuron

Billions Billions neurons and more glial cells fneurons and more glial cells form human nervous systemorm human nervous system..

It is the structural and functional unit It is the structural and functional unit of the nervous of the nervous tissue.tissue.

Neuron consists of cell Neuron consists of cell body(soma), dendrite and axon.body(soma), dendrite and axon.

Neuron is a cell that Neuron is a cell that receive the receive the stimulation ,conduct the nerve stimulation ,conduct the nerve impulse andimpulse and transmit the the impulse.

Cell body

Dendrite

Axonprocesses

① Cell body of neuron (soma)

① Cell body of neuron (soma)

① soma

Nissl body(tigroid body)Location: located in cytoplasma and large dendritesLM: basophilic spot-liked or granule-liked structureEM: parallelly-arranged RER and free ribosomeFunction: synthesis of proteins, enzymes and neurotransmitters

Spinal Spinal ganglionganglion

motor motor neuron from neuron from Spinal cordSpinal cord

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, microtubuleFunction: supporting(cytoskeleton), involving in intracellular transportation

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

Exercises

Answers and Explanations1-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

The axon hillock contains(A) rough endoplasmic

reticulum(B) ribosomes(C) microtubules(D) Golgi complex(E) synaptic vesicles

Exercises

Answer and ExplanationC. The axon hillock contains microtubules, which are arranged in bundles.

2. Synapses

2. Synapses Specialized junctions between neurons,

between axons and effector cells

Electrical synapsesgap junctions

Chemical synapses taking neurotransmitter as communicating medium

Classification

Chemical synapse

Synaptic transmissionSynaptic transmission

Calcium gates openCalcium gates open Synaptic vesicles release neurotransmitterSynaptic vesicles release neurotransmitter Neurotransmitter binds with postsynaptic recNeurotransmitter binds with postsynaptic rec

eptorseptors The postsynaptic membrane is excited or inhiThe postsynaptic membrane is excited or inhi

bitedbited The neurotransmitter is degraded and recycleThe neurotransmitter is degraded and recycle

d.d.

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

Exercises

Answer and ExplanationC. 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 cellSchwann cell envelop the axon end to end to envelop the axon end to end to

form myelin-sheath in PNS and form myelin-sheath in PNS and

Satellite cellSatellite cell (capsular cell) (capsular cell) one layer of flattened or cuboidal one layer of flattened or cuboidal

cell, with round, ovoid and dark Ncell, with round, ovoid and dark N surrounding the Neuron in surrounding the Neuron in

ganglionganglion

4.Nerve fiber and 4.Nerve fiber and NerveNerve

Nerve fiber Nerve fiber

definition: definition: axon enveloped by axon enveloped by neuroglial cellsneuroglial cells

classification: classification: according to myelin-according to myelin-sheathsheath

myelinated nerve fibermyelinated nerve fiber unmyelinated nerve fiberunmyelinated nerve fiber

myelinated nerve fibermyelinated nerve fiber in CNS---structure: similar to in PNS myelin-sheath formed by flattened end

ing of oligodendrocyte’s processes one oligodendrocyte can envelop man

y axons no incisure and basement membrane

NerveNerve

5. Nerve Ending