1 structure functions nerve cells

ANATOMY PHYSIOLOGY IV

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Prepared by: Miss Nadiah Shamsuddin

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LEARNING OBJECTIVES

At the end of the learning session, students will able to: Describe the histological characteristic and

the functions of neurons and neuroglia. Distinguish between gray matter and white

matter.

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Introduction

Nervous tissue consist of two types of cells:

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neurons

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NERVE CELLS (NEURON)

Specific cells that transport electrical nerve impulse.

Transport impulse from one part to others part of body.

Property: Electrical excitability (ability to produce action

potential and impulse in response stimuli). Once they arise, action potentials propagate from

one point to the next along the plasma membrane due to the presence of specific types of ion channels.

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Nerve Cells Nerve fiber is a general term for any

neuronal process (dendrite or axon) The site of communication between two

neurons or between a neuron and an effectors cell is called a synapse.

(Neuron synapse neuron) Impulses transmit into neuron at synapse

through dendrite process and carry incoming impulse towards cell bodies. Then transfer away from cell body by axon.

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CELL BODY

Contains: Nucleus

Surrounded by cytoplasm that includes typical organelles such as:

lysosomes, mitochondria and a Golgi complex

Nissl bodies (prominent cluster of rough endoplasmic reticulum) :

sites of protein synthesis in neurons that was used to replace cellular components, as a material for growth of neurons and to regenerate damaged axons in the PNS.

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Cell body

Characteristics: Different sizes with others Protoplasma have granules Neurons cells cannot divide like others cell

body Form grey matter in brain and spinal cord Cells have one or more fibers (axons and

dendrite) will form white matter nervous system’s organs .

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DENDRITE

Dendrite’s shorter processes terminating mostly near the nerve cell body. They touch the others neuron at synapse.

Are conductive in nature : receive and carry incoming impulses towards cell

bodies. Have same structures like axons, but are

usually shorter and branching. In motor neuron, they forms part of synapses. In sensory neuron, they form the sensory

receptors that respond to specific stimuli.

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AXON

Each neuron has one axon. Axon may have branches along their

length known as axon collaterals. Axon collaterals is divide into many

fine processes known as axon terminals.

Axon terminals: Longer than dendrites , sometimes about

1 metre.

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AXON

Has a long central core of cytoplasma called axosplasma .

The cytoplasma is surrounded by plasma membrane axolemma.

Together axoplasma with axolemma is called as axis cylinder of the nerve fiber.

Axon: the conducting region of the neuron. It generates nerve impulses and transmit

them (typically away from the cell body.)

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AXON

Insulated by myelin sheath It gives white colour to the nerve fiber.

Has a series of Schwann cell plasma membrane and also known as neurolemma.

There are tiny areas of exposed axolemma between adjacent Schwann cells, called nodes of Ranvier.

Nodes of Ranvier: Assist in rapid transmission of nerve impulse. (the speed of transmission of nerve impulse slower

in non-myelinated fibers.)

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Functions of Myelin Sheath17

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Neurolemma

A series of Schwann cell plasma membrane - Thin membrane surrounding the myelin

sheath that found only around axons in the Peripheral Nervous Sytem.

When the axon is injured, neurolemma assists regenerations.

It forms a regeneration tube that guides and stimulates growth of the axon.

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Properties of neuron19

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Classification of neuron 20

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Classification of neuron22

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Classification of neuron23

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Classification of neuron

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Classification of neuron25

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Nerve Impulse

The electrical activity in the membrane of a neuron.

Ways by which information is transmitted within the nervous system along the axons of the neurons.

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Types of neuron 28

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Types of neuron: Sensory or Afferent Nerves Nerve that transmit impulse from peripheral

body through spinal cord to the brain to be interprets.

Example: from skin. When action potentials are generated by

sensory receptors on the dendrites of these neurons, they are transmitted to the spinal cord by the sensory nerve fibers.

The impulse may then pass to the brain or to connector neurons of reflex arcs in the spinal cord.

Sensory receptors action potentials dendrites sensory nerve fibers spinal cord brain / connector neuron of spinal cord.

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Types of neuron: Sensory or Afferent Nerves Sensory nerves from peripheral nerve

are non-myelinated and not have neurolemma. From small division called as sensory nerve ending.

Stimulation; pain, hot temperature impulse transmit to sensory nerve brain

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Types of neuron: Motor or Efferent Nerves Nerve that send impulse from brain to

spinal cord. Then it goes to skeletal muscle to contract.

Brain spinal cord skeletal muscle (contract).

The nearer motor nerve to muscle, it lost its myelin sheath and neurolemma.

The nerve branches into filament and ends at Motor End Plate.

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NEUROGLIA

It is about half the volume of the Central Nervous System (50%).

It held nervous tissue together.

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6 Types of Neuroglia34

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Differences between Neuroglia & Neuron

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General Functions of Neuroglia

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Neuroglia: Astrocytes37

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Neuroglia: Oligodendroglia / oligodendrocyte

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Neuroglia: Microglia 39

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Neuroglia: Ependymal cells 40

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