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33 Cards in this Set
- Front
- Back
How do neurons differ from other cells of the body
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Highly polarized
Cell body is usually less than a tenth of cell volume Cells are excitable |
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How do axons differ from dendrites
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Dendrites typically are smaller in diameter and shorter in length axons conduct the output of the cell while dendrites conduct the input of the cell(receiving inputs at spines) dendrites contain organelles necessary for protein synthesis
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When talking about synaptic input what are the trends of inhibitory synapse and excitatory synapse in location
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Inhibitory usually more close to cell body while excitable ones are further away
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What cells are responsible for myelin and how do they differ
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PNS Schwann cells myelin axons and the genes turn on in the presence of axons while in the CNS oligodendrocytes turn on due to the presence of other glia cells like astrocytes
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MAG
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Myelin associated protein- major protein associated with mature myelin
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Importance of the golgi method
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discovered by Camillo Golgi 1873 but used by Cajal that developed a silver impregnation that allowed microscopic visualization of the neuron and cajal was able to correctly surmise that the neuron exist as a intricate network of individual neurons
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What are the six regions of the brain and function
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spinal cord- most caudal part control movements of the limbs and the trunk
, medulla oblongata- vital autonomic functions , pons (and cerebellum)- conveys information about moving midbrain- rostral to pons controls many sensory and motor functions diencephalon- (thalamus process most of the information reaching the cerebral cortex. and cerebral hemispheres. memory storage coordination |
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what are the four regions of the cerebral cortex and what general functions are localized there
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frontal- planning for future action and control of movement
parietal- somatic sensation and body image occupital- vision and temporal lobes learning memory emotion and hearing |
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unipolar cells
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single process are characteristics of the invertebrate nervous system
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bipolar cells
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two processes the dendrite , the axon
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multicellular cells
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which have an axon and many dendritic processes are the most common pyramidal cell, purkinje cell
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describe how signaling in all neuron
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input signal (receptor potential)
synaptic potential (in interneuron or motor neuron) integration signal (c0nDuctioin signal) output signal |
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what are the three ways in which constituents move within the axon
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1. fast anterograde (forward moving)
2. slow axoplasmix flow 3. fast retrograde transport |
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Fast anterograde transport depends on....
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not affected by inhibitors of protein synthesis, but depends more on the filaments that make up the neurons cytoskeleton, fast antergrade transport depends on the microtubule that provide a stationary track in which specific organs move in saltatory fashion
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the motor molecule for anterograde movement is...
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kinesin
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slow anterograde transport
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There are two classes of slow anterograde transport: slow component a (SCa) that carries mainly microtubules and neurofilaments at 0.1-1 millimeter per day, and slow component b (SCb) that carries over 200 diverse proteins and actin at a rate of up to six millimeters a day.[8] The slow component b, which also carries actin, are transported at a rate of 2-3 mm/day in retinal cell axons.
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fast retrograde transport
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Retrograde transport, which is mediated by dynein, sends chemical messages, and endocytosis products headed to endolysosomes from the axon back to the cell.[5] Fast retrograde transport can cover 100-200 millimeters per day.[5]
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microtubules
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is the thickest of the neurons cytoskeletal fibers. in the axon they are oriented longitudinally with polarity always in the same direction with the plus end pointing to the axon terminus
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why was neurofilaments important to the golgi method
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typically the most abundant fibrillar components in axons and are the bones of the cytoskeleton important because they are the elements that retain silver nitrate first applied by golgi
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microfilaments
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the thinnest if the three type they are polar polymers of globular actin monomers wound into two stranded helix they interact with integrin a family of membrane spanning proteins
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What are the three main signals that can gate channels
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Voltage, chemical, mechanical
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What is the measure Of conductance
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Reciprocal of resistance which provides an electrical measure of ion permeability
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Ligand and voltage channels enter refractory stages differently describe both
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Ligand gated channels enter via desensitization when you have an excess of ligands and with voltage gated channels the process is termed deactivation
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By convention Vm is defined by
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Vin- Vout and is usually -60 to -70
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Define
Ion intercellular extracellular nernst K Na Cl ion of squid giant axon |
K 400 20 -75
Na 50 440 +55 Cl 52 560 -60 A- 385 |
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When a cell has depolarized what processes occur to return it back to resting potential
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Sodium channels inactivates in a time dependent manner
Delayed opening of k channels increases k efflux until cell depolarizes |
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What are the permeability ratios of the membrane at rest
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Pk:PNa:pCl 1/0.04/0.45
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What are the permeability ratios of the membrane at the peak of an action potential
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1/20/0.45
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In the equivalent circuit model for the neuron the ion channel represents?
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Conductor and battery. An ion going through the channel is likely to interact with the sides. Also a difference in ion concentration inside and out the cell creates an electromotive force
Gk=Nk x gk |
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In the equivalent circuit model what does the membrane represent
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A leaky capacitor where V=q/c a typically capacitance value is 1 uf/cm2
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I na=
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Gna x (vm-ena)
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When you have a stepwise current injection you notice a voltage response that rises and decays more slowly than a step change in current why is that
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capacitance
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myelination increases speed of conduction by
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increasing rm and decreasing cm
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