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Nervous systemNervous system
Central nervous systemCentral nervous systemBrainBrainSpinal cordSpinal cord
Peripheral nervous systemPeripheral nervous systemNervesNervesGangliaGangliaNerve endingsNerve endings
Nervous tissueNervous tissueNervous tissueNervous tissue
supporting cellssupporting cellsGLIAL CELLSGLIAL CELLS
supporting cellssupporting cellsGLIAL CELLSGLIAL CELLS
nerve cellsnerve cellsNEURONSNEURONSnerve cellsnerve cellsNEURONSNEURONS
DendritesDendrites
Multiple processesMultiple processes Receptor processesReceptor processes Usually shortUsually short Branch profusely forming Branch profusely forming
a dendritic treea dendritic tree Become thinner as they subdivide Become thinner as they subdivide
into branchesinto branches
AxonsAxons
Single processesSingle processes Effector processesEffector processes Usually longUsually long Don’t branch profusely Don’t branch profusely Ends in terminal arborization – Ends in terminal arborization –
telodendrontelodendron Have constant diameterHave constant diameter
Types of neuronsTypes of neurons
Sensory (afferent)Sensory (afferent) Motor (efferent)Motor (efferent) InterneuronsInterneurons
Types of neuronsTypes of neurons
Bipolar neuronsBipolar neurons Retina Retina Olfactory mucosaOlfactory mucosa Cochlear and Cochlear and
vestibular gangliavestibular ganglia PPseudounipolar seudounipolar
neuronsneurons Sensory neuronsSensory neurons
MultiMultipolar neuronspolar neurons Motor Motor nneuronseurons InterneuronsInterneurons
Nuclei of glial cells Nuclei of glial cells
dendritedendrite Axon hillock Axon hillock
Nissl bodies Nissl bodies Nissl bodies Nissl bodies
rough endoplasmic reticulum rough endoplasmic reticulum cisternaes and free ribosomescisternaes and free ribosomesrough endoplasmic reticulum rough endoplasmic reticulum cisternaes and free ribosomescisternaes and free ribosomes
Types of synapsesTypes of synapses
AxosomaticAxosomaticAxodendriticAxodendriticAxoaxonicAxoaxonic
Types of synapsesTypes of synapses
ExcitatoryExcitatory InhibitoryInhibitory
Types of glial cellsTypes of glial cells
Central nervous systemCentral nervous system OligodendrocytesOligodendrocytes AstrocytesAstrocytes Ependymal cellsEpendymal cells MicrogliaMicroglia
Peripheral nervous systemPeripheral nervous system Schwann cellsSchwann cells Satellite cellsSatellite cells
AstrocytesAstrocytes Glial cells of central nervous systemGlial cells of central nervous system 2 types 2 types
ProtoplasmicProtoplasmic
FibrousFibrous
support neuronssupport neurons surround neurons, blood vessels, synapsessurround neurons, blood vessels, synapses form a layer on outer surface of the brain and spinal cordform a layer on outer surface of the brain and spinal cord control ionic and chemical environment of neuronscontrol ionic and chemical environment of neurons regulate neuronal activity and metabolismregulate neuronal activity and metabolism joined to one another by gap junctions forming joined to one another by gap junctions forming
a continous networka continous network
AstrocytesAstrocytes
Blood vesselBlood vessel
Microglial cells – MicrogliaMicroglial cells – Microglia
glial cells of central nervous glial cells of central nervous systemsystem
phagocytic cells – belong to phagocytic cells – belong to mononuclear phagocytic mononuclear phagocytic systemsystem
macrophages of CNSmacrophages of CNS derive from precursor cells in derive from precursor cells in
bone marrowbone marrow involved in inflammation involved in inflammation
processes in CNSprocesses in CNS phagocyte dead neurons and phagocyte dead neurons and
an excess of neurons during an excess of neurons during embryogenesisembryogenesis
Ependymal cellsEpendymal cells glial cells of CNSglial cells of CNS cuboidal cellscuboidal cells line the ventricles of the brain line the ventricles of the brain
and the central canal of the spinal cordand the central canal of the spinal cord
OligodendrocytesOligodendrocytes glial cells of CNSglial cells of CNS have only a few small processeshave only a few small processes myelin – forming cells in CNSmyelin – forming cells in CNS
Cells forming the myelin sheathCells forming the myelin sheathCells forming the myelin sheathCells forming the myelin sheath
CNSCNSOligodendrocytesOligodendrocytes
CNSCNSOligodendrocytesOligodendrocytes
PNSPNSSchwann cellsSchwann cells
PNSPNSSchwann cellsSchwann cells
Schwann cellSchwann cellInternodeInternode
Node of RanvierNode of Ranvier
Peripheral nervous systemPeripheral nervous systemPeripheral nervous systemPeripheral nervous system
Unmyelinated fibersUnmyelinated fibers
One Schwann cell→ several axonsOne Schwann cell→ several axons
Unmyelinated fibersUnmyelinated fibers
One Schwann cell→ several axonsOne Schwann cell→ several axons
Myelinated fibersMyelinated fibers
One Shwann cell→ one axonOne Shwann cell→ one axon
Myelinated fibersMyelinated fibers
One Shwann cell→ one axonOne Shwann cell→ one axon
Shwann cellShwann cell
Shwann cellShwann cell
AxonAxon
AxonsAxons
OligodendrocyteOligodendrocyte
Central nervous systemCentral nervous systemCentral nervous systemCentral nervous system
Unmyelinated fibersUnmyelinated fibers
Bare nerve fibers Bare nerve fibers – not imbedded in glial cells– not imbedded in glial cells
Unmyelinated fibersUnmyelinated fibers
Bare nerve fibers Bare nerve fibers – not imbedded in glial cells– not imbedded in glial cells
Myelinated fibersMyelinated fibers
OligodendrocytesOligodendrocytes
Myelinated fibersMyelinated fibers
OligodendrocytesOligodendrocytes
Peripheral nervous systemPeripheral nervous system
nervesnerves sensory nervessensory nerves motor nervesmotor nerves mixed nervesmixed nerves
gangliaganglia nerve endingsnerve endings
EpineuriumEpineurium
PerineuriumPerineurium
EndoneuriumEndoneurium
NerveNerve
EEndoneurium – loose connective tissuendoneurium – loose connective tissue PPerineurium – a few layers of flattened erineurium – a few layers of flattened
epithelium – like cellsepithelium – like cells EEpineurium – dense irregular connective pineurium – dense irregular connective
tissue containing blood vesselstissue containing blood vessels
Nucleus of nerve cellNucleus of nerve cell
Satelite cells Satelite cells NucleolusNucleolus
Sensory gangliaSensory ganglia
lie in dorsal roots of spinal cord, outside of CNSlie in dorsal roots of spinal cord, outside of CNS contain cell bodies of sensory neurons – contain cell bodies of sensory neurons –
pseudounipolar pseudounipolar 2 regions2 regions
central region – nerve fiberscentral region – nerve fibers peripheral region – cell bodiesperipheral region – cell bodies
cell bodies are covered by satellite cellscell bodies are covered by satellite cells satellite cells – a kind of glial cells of PNSsatellite cells – a kind of glial cells of PNS
Nervous systemNervous system
Somatic nervous system – voluntary Somatic nervous system – voluntary functions – functions – control skeletal musclescontrol skeletal muscles
Autonomic nervous system – Autonomic nervous system – involuntary functions – involuntary functions – control smooth control smooth muscle, secretion of some glands, modulation of muscle, secretion of some glands, modulation of cardiac rhythmcardiac rhythm
Autonomic nervous systemAutonomic nervous system
Sympathetic system – Sympathetic system – presynaptic presynaptic neurons are located in thoracic and lumbar neurons are located in thoracic and lumbar segments of spinal cordsegments of spinal cord
Parasympathetic system – Parasympathetic system – presynaptic presynaptic neurons have their nuclei in medulla, midbrain, neurons have their nuclei in medulla, midbrain, sacral portion of spinal cordsacral portion of spinal cord
Nerve endingsNerve endings
afferent – sensory receptorsafferent – sensory receptors efferentefferent
Sensory receptorsSensory receptors
exteroceptorsexteroceptors proprioceptorsproprioceptors interoceptorsinteroceptors
Sensory Sensory rereceptorsceptors
NonencapsulatedNonencapsulated Free nerve endingsFree nerve endings Merkel endingsMerkel endings
EncapsulatedEncapsulated Meissner corpuscleMeissner corpuscle Pacinian corpusclePacinian corpuscle Ruffini corpuscleRuffini corpuscle
Free nerve endingsFree nerve endings
Found in skin and Found in skin and corneal epitheliumcorneal epithelium
Terminate in Terminate in epidermisepidermis
Devoid of Schwann Devoid of Schwann cells and myelincells and myelin
Respond to touch, Respond to touch, heat, cold, painheat, cold, pain
Merkel endingMerkel ending
Nerve endings are Nerve endings are attached to Merkel attached to Merkel cellscells
Merkel cells – Merkel cells – modified epidermal modified epidermal cells located in skincells located in skin
Mechanoreceptors – Mechanoreceptors – sensitive to touchsensitive to touch
Pacinian corpusclesPacinian corpuscles Encapsulated receptorsEncapsulated receptors Ovoid structure resembling Ovoid structure resembling
a hemisected oniona hemisected onion Nerve ending is Nerve ending is
surrounded surrounded by concentric lamellae of by concentric lamellae of flattened cellsflattened cells
Found in hypodermis and Found in hypodermis and deed fascia tissuesdeed fascia tissues
Respond to vibrations and Respond to vibrations and deep pressuredeep pressure
Meissner’s corpusclesMeissner’s corpuscles
Encapsulated receptorsEncapsulated receptors Contain Schwann cells that Contain Schwann cells that
form irregular, tortuous form irregular, tortuous lamellaelamellae
Nerve fibers pass between Nerve fibers pass between lamellaelamellae
Found in the papillary layer Found in the papillary layer of hairless skin (lips, of hairless skin (lips, fingers, hands, foots)fingers, hands, foots)
Respond to touchRespond to touch
ProprioceptorsProprioceptors
Muscle spindlesMuscle spindles Golgi tendon organsGolgi tendon organs
Degeneration and regeneration of Degeneration and regeneration of peripheral nerve - stepsperipheral nerve - steps
1.1. Schwann cells proliferate and bridge the scar.Schwann cells proliferate and bridge the scar.
2.2. The axon degenerateThe axon degenerate Anterograde degeneration – (refers to distal segment) – comprise the Anterograde degeneration – (refers to distal segment) – comprise the
whole distal segment including axon and myelin sheathwhole distal segment including axon and myelin sheath Retrograde degeneration – (refers to proximal segment) –extends for a Retrograde degeneration – (refers to proximal segment) –extends for a
short distanceshort distance
3.3. Debris is phagocyted by macrophages.Debris is phagocyted by macrophages.
4.4. The cell body undergoes chromatolysis.The cell body undergoes chromatolysis.
5.5. The muscle fiber shows a denervation atrophy.The muscle fiber shows a denervation atrophy.
6.6. Shwann cell prolipherate within a connective tissue sleeve.Shwann cell prolipherate within a connective tissue sleeve.
7.7. The axon grows and penetrate the Schwann cell columns.The axon grows and penetrate the Schwann cell columns.
8.8. Schwann cells produce myelin sheath on the regenerated axon.Schwann cells produce myelin sheath on the regenerated axon.