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Ch 9 Nervous tissue
I.Organization of Nervous System
A. CNS (central nervous system)
1. Divisions
a. brain
b. spinal cord
2. function
a. interpretsb. directsB. PNS (peripheral nervous system)
1. defined2. divisions
a. Nerves
1. spinal nerves2. cranial nervesFunction: Communication lines3. Functional subdivisions
a. Sensory (afferent) division1. information2. receptorsa. somaticb. viscersalb. Motor (efferent) division1. somatic nervous system
a. motor nerves2. autonomic nervous system (ANS)
a. visceral motor nervesb. sub-divisions
1. sympathetic2. parasympathetic-
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II. Histology of Nervous Tissue
A. Principal cells:
1. support cells2. neurons3. neurogliaB. Neuroglia
1. functiona. segregate
b. insulatec. growth2. types..glia fig 11.3
a. CNS types
1. Astrocytesa. structureb. functions
1. transport2. migration3. chemical Equilibrium4. cell signaling2. Microglia (small glia)
a. structureb. functions
1. macrophage2. phagocytize3. protective role3. Ependymal cells (wrapping)
a. structureb. functions
1. line2. barrier between cerebral spinal fluid and…
3. circulation
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4. Oligodendrocytes- (few processes)
a. structureb. function
1. wrapa. myelin sheathb. ANS nuroglia
1. Satellite cellsa. function2. Schwann cells (neurolemmocytes)a. function
1. regerative-
C. Neurons-(nerve cells)1. characteristics
a. longevityb. amitotic1. exceptions-olfactory and hippocampal neurons
2. Structure
a. Cell Body (perikaryon)1.
2. centrioles3. organellsa. ER- nissl bodies, chromatophillic substances
b. cytoskeletal fibersc. lipofuscin..a by product of lysosomal activity4. outgrowth5. clustersa. ganglia-
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b. Processes in CNS (2 types)
1. Dendrites-(fig 11.4)
a. structureb. organellsc. function
1. receive(input)a. graded potentials2. The Axon
a. origin1. Axon hillock (fig 11.4)b. lengthc. branches1. axon collaterals2. terminusa.
d. axonal terminalse. functions
1. conduction2. originates at axon hillock3. ends at axon terminalsf. organells1. exceptions
a. lack..
1.
2.
b. no protein synthesisc. dependenceg. movement1. anterogradea. mitochondria, cytoskeletal elements, nerotransmitters,..
2. retrogradea. communication back to the body (soma)-
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h. Axolemma-
D. Myelin Sheath
1. neurons2. characteristicsa.
b.
3. functions
a.
b. electric insulationc. separation4. axons*5. dendrites6. PNS- myelin sheath covering is accomplished by…
a. Schwann cells-(fig 11.5)
1. channel/carrier proteins2. neurolemma3. nodes of ranvier (neurofibril nodes)a. In the cns
1. nodes2. lack neurolemma7. White Matter8. Grey matterE. Classification of Neurons (see table 11.1)
1. structural classificationa. multipolar neurons1. cns
2. percentage multipolarb. Bipolar neurons1.
2.
3. location-
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c. Unipolar neurons1. branches
a. proximal
b. distal2. pseudounipolar neuronsa. bipolar 
2. Functional classification:
a. Sensory (afferent) neurons1. unipolarb. Motor (efferent) neuronsc. Interneurons (association neurons)
1. located-
III. Neurophisiology- Irritability (response to stimuli)
A. Electricity
1. Voltagea. measured2. Potential differencea. high voltage3. current4. resistance5. ohms lawSummary: In the body…
1. current2. potential difference3. resistanceB. Ion channels
1. type
a. passive-
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b. active1. ligand gated2. voltage-gated3. mechanical gated2. Open channels3. Closed channels4. electrochemical gradienta. Electrob. ChemicalC. Resting Membrane Potential
1. defined2. polarized*3. value4. varies5. occursa. charge of attraction6. ionic concentrationa. Na+ b. K+ 7. permeabilitya. impermeableb. permeable
1. Na+ 2. K+ 3. Cl- c. equilibrium1. Na-K pump
D. Membrane Potentials1. communicationa. neuronsb. changes inc. signal types
1. graded potentials2. action potentials-
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d. depolarizationex: from -70mV to -65mV is a depolarization!!!
e. hyperpolarization2. Graded potentials
a. short lived
b. local change1.
2.
* c. definedd. stimuli1. generator potential2. post synaptic potential3. Action Potentialsa. cell typesb. membrane potential
1. change in voltage2. depolarization3. repolarizationc. Events of an Action Potential
1. gates at Resting Phase
a. Na+ activation gateresting: closed
depol: open
b. Na+ inactivation gatec. depolarizationd. K+ channels2. Depolarization Phase
a. Na+ gatesb. K+ gatesc. progressive depolarizationd. thresholde. membrane potential (fig 11.13a)
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f. positive feedback3. Repolarizationa. decrease-(fig 11.12 graph)1. cause2. Na+ inactivation gates3. net Na+ influx4. increase1. voltage-gated K+ chnlsa. returnsSummary: abrupt decline of Na+ ______________ and an increase in
________ permeability _______________.
4. Hyperpolarizationa. K+ gateb. excessivec. Na+ chnlsd. result (see fig 11:12)5. Ionic distributiona. repolarizationb. Na-K pumpD. Propogation1. movementa. action potentialb. away from stimulusEx: an electrode can touch a nerve and the impulse moves away in both
directions
 (stimulus) 
c. self propogatingd. neuron types1.
a. salutatory conduction2.
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2. Thresholda. sufficient stimulusb. dependsc. subthreshold3. All or none effecta. threshold4. Refractory perioda. absoluteb. relative refractory1. threshold stimulus2. exceptional stimulusa. reopenb. initiate5. Conduction Velocitiesa. vary1. slow2. axon diameter
a. lg diameterb. small diameter3. degree of myelination
a. unmylinatedb. myelinated1. salutatory conduction (fig 11.16)E. The Synapse1. where2. axodentric synapses3. axosomatic synapse4. axoaxonic
a. dendrodendriticb. dendrosomatic-
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5. pre-synaptic neuronsa. post synaptic neuronb. distribution6. Types of communication (synaptic)
a. electrical1. gap junctionsa. connexins2. electrically coupled3. function
a. important in cnsb. stereotyped movementc. embryonic-
b. chemical synapses1. axonal terminal2. receptor region3. synaptic cleftF. Events at a Chemical Synapse
a. depolarization- at axonal terminal
b. Ca++ chls – open ca influx
c. synaptic vesicles- move to fuse with axonal membrane for…
d. exocytosis- of neurotransmitters into synaptic cleft
e. diffuse/migrate- to reseptors on post synaptic membrane
f. binding- causes channels to open
1. excitation or inhibition
g. enzymes- in synaptic cleft degrade neurotransmitters
1. cholinesternase
h. reuptake- of nerotransmitters into pre synaptic neuron
G. EPSP’s and IPSP’s
1. EPSPa. thresholdb. influxc. efflux-
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d. graded depolarization
e. function2. IPSP’sa. thresholdb. resultsc. permeability1. K+ 2. ClH. Summation: two kinds
1. EPSP’s- added 
a. temporal1. a EPSP before…
b. spatial2. functionsummary: after summation you may have IPSP’s and EPSP’s at the
same time to facilitate the control of depolarization.
IV. Neurotransmitters (language of the nervous system)
A. Types- more then 50 types
1. excitatory2. inhibitory3. chemical or _____________
4. direct or ______________
5. receptor6. effectors7. cns and pns
NOTE: see table 11.3, know neurotransmitter, site, and effect
See fig 11.23, Receptor mechanisms
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V. Neuronal circuitsA. intergrated1. diverging –(see fig 11.25)a. amplify2. converginga. effect1.
2.sensory3. oscillating (reverberating)-see fig 11.25e a. producesb. rhythmic control4. parallel after- dischargea. cognition…
NOTE: Review ALL clinical terms…
Review ALL homeostatic disfunctions…learn them!!
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