glial cells Pages 227234 Astro cytes Braceanchor neurons provide chemical barrier Most abundant glial cells Microglia Destroy threatening particlescells phagocytes Ependymal cells ID: 692608
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Slide1
Nervous Tissue:Neurons and Support Cells (glial cells)
Pages 227-234Slide2
AstrocytesBrace/anchor neurons, provide chemical barrier
Most abundant
glial cellsMicrogliaDestroy threatening particles/cells; phagocytesEpendymal cellsLine ventricles and central canal; cilia circulate CSFOligodendrocytesProduce myelin sheath around axons (in the CNS)
© 2015 Pearson Education, Inc.
Support Cells:
NeurogliaSlide3
Figure
7.3a Supporting (glial) cells of nervous tissue.
Capillary
Neuron
Astrocyte
(a
) Astrocytes are
the most abundant
and versatile neuroglia.
ASTROCYTESSlide4
Figure
7.3b Supporting (glial) cells of nervous tissue.
Neuron
Microglial
cell
(b) Microglial cells are phagocytes that
defend CNS cells.
MICROGLIASlide5
Figure
7.3c Supporting (glial) cells of nervous tissue.
Ependymal
cells
Brain or
spinal cord
tissue
Fluid-filled cavity
(c) Ependymal cells line cerebrospinal
fluid-filled cavities.
EPENDYMAL CELLSSlide6
Figure
7.3d Supporting (glial) cells of nervous tissue.
Myelin sheath
Process of
oligodendrocyte
Nerve
fibers
(d)
Oligodendrocytes
have processes that form
myelin sheaths around CNS nerve fibers.
OLIGODENDROCYTESSlide7
Satellite cellsProtect neuron cell bodiesSchwann cells
Form myelin sheath
around axons (in the PNS)© 2015 Pearson Education, Inc.Support Cells: PNS glial cellsSlide8
Figure
7.3e Supporting (glial) cells of nervous tissue.
Satellite
cells
Cell body of neuron
Schwann cells
(forming myelin sheath)
Nerve fiber
(e) Satellite cells and Schwann cells (which
form myelin) surround neurons in the PNS.Slide9
specialized to transmit messagesMajor regions of neuronsCell
body
—contains the nucleusmetabolic center of the cellProcesses—fibers that extend from the cell body Dendrites : pick up sensory stimuliAxons : receive impulse from cell bodyImpulses are UNIDIRECTIONAL along the axon
© 2015 Pearson Education, Inc.
Neurons (nerve cells)Slide10
Figure
7.4a Structure of a typical motor neuron.
Mitochondrion
Nucleus
Dendrite
Cell body
Axon
One Schwann cell
Node of Ranvier
Schwann cells,
forming the myelin
sheath on axon
Axon
terminal
(a)Slide11
Figure
7.4b Structure of a typical motor neuron.
Neuron
cell body
Dendrite
(b)Slide12
End in axon terminalsTerminals contain vesicles filled with neurotransmitters
Neurons are separated from other cells by
a gap called the synaptic cleft:Synapse—junction between nervesNeurons NEVER touch each other© 2015 Pearson Education, Inc.
Axons and the Synaptic CleftSlide13
The Myelin Sheath
whitish
, fatty material covering axonsNodes of Ranviergaps in myelin sheath along the axonimpulse jumps from one node to the nextThe current cannot flow across the axon where there is myelin so it jumps between the myelin bundles
The presence of the myelin sheath speeds the nerve impulse
transmission
© 2015 Pearson Education, Inc.Slide14
Myelin sheath becomes destroyedReplaced with hardened sclerosesSclerosis: hardening of body tissue
Incomplete/staggered transmission of impulse
Autoimmune disease- potientially caused by:GenesSmokingViral infectionsVitamin D deficiencyMultiple SclerosisSlide15
Sensory (afferent) neuronsCarry impulses from
sensory
receptors to the CNSCutaneous (skin) sense organsPain receptorsTemperature receptorsTouch/pressure receptorsProprioceptors—detect stretch or tension
Muscle spindle in musclesGolgi tendon organ in tendonw
© 2015 Pearson Education, Inc.
Classification
of NeuronsSlide16
Motor (efferent) neuronsCarry impulses from the central nervous system to viscera, muscles, or glands
Interneurons
(association neurons)Located in the spinal cord (CNS)Connect sensory and motor neuronsPlay role in reflex arc – allow quicker response without involving the brain© 2015 Pearson Education, Inc.
Functional Classification of NeuronsSlide17
Figure
7.6 Neurons classified by function.
Dendrites
Peripheral
process (axon)
Ganglion
Cell
body
Sensory
neuron
Central process (axon)
Spinal cord
(central nervous system)
Interneuron
(association
neuron)
Afferent
transmission
Peripheral
nervous system
Receptors
Efferent transmission
Motor neuron
To effectors
(muscles and glands)