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 tissue Two types of cells Two types of cells ---Components: nerve cell: neuron nerve cell: neuron Glial cell: neuroglial Glial cell: neuroglial---Function: Neurons : receive the stimulation, conduct the nerve impulse, the Neurons : receive the stimulation, conduct the nerve impulse, transmit the impulse Glial cell: support, protect and insulate, nourish neurons Glial cell: support, protect and insulate, nourish neurons

1. Neuron

Billions neurons and more glial cells form human nervous system. Billions neurons and more glial cells form human nervous system. It is the structural and functional unit of the nervous tissue. It is the structural and functional unit of the nervous tissue. Neuron consists of cell body(soma), dendrite and axon. Neuron consists of cell body(soma), dendrite and axon. Neuron is a cell that receive the stimulation,conduct the nerve impulse and the Neuron is a cell that receive the stimulation,conduct the nerve impulse and transmit the impulse.

Cell body Dendrite Axon processes

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

Spinal ganglion motor neuron from Spinal 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, microtubule Function: 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 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

The axon hillock contains (A) rough endoplasmic reticulum (B) ribosomes (C) microtubules (D) Golgi complex (E) synaptic vesicles Exercises Answer and Explanation C. The axon hillock contains microtubules, which are arranged in bundles.

2. Synapses

Specialized junctions between neurons, between axons and effector cells

Electrical synapses gap junctions Chemical synapses taking neurotransmitter as communicating medium Classification

Chemical synapse

Synaptic transmission Calcium gates open Calcium gates open Synaptic vesicles release neurotransmitter Synaptic vesicles release neurotransmitter Neurotransmitter binds with postsynaptic receptors Neurotransmitter binds with postsynaptic receptors The postsynaptic membrane is excited or inhibited The postsynaptic membrane is excited or inhibited The neurotransmitter is degraded and recycled. The neurotransmitter is degraded and recycled.

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 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)

Schwann cell envelop the axon end to end to form myelin-sheath in PNS and envelop the axon end to end to form myelin-sheath in PNS and

Satellite cell (capsular cell) Satellite cell (capsular cell) one layer of flattened or cuboidal cell, with round, ovoid and dark N one layer of flattened or cuboidal cell, with round, ovoid and dark N surrounding the Neuron in ganglion 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 myelinated nerve fiber unmyelinated nerve fiber unmyelinated nerve fiber

myelinated 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