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70 Cards in this Set
- Front
- Back
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Schwann cells
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myelinating cells of PNS
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Wallerian Degeneration
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After injury to axon, myelin/axon distal degenerate. Schwann cells proliferate to guide regrowth. secrete nerve growth factor
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Oligodendrocytes
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myelinating cells of CNS; are attached in MS. capable of some remyelination.
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Astrocytes
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star-shaped cells that encircle CNS neurons, provide metabolic support, regulate blood flow, maintain BBB
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glia limitans
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astrocytic end feet that contact blood vessels make up thi delicate network that helps maintain BBB
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astrocyte communication
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numerous gap junctions allow them to spread signals
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most common brain tumor
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astrocytoma
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astrocytic scarring
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astrocytes proliferate, hypertrophy after injury, sealing off wound. helps limit damage but may prevent neurons from regenerating.
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Ependymal cells
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simple epithelium along ventricles; lack TJ so allow CSF to reach equilibrium w/ brain tissue. Specialized ones make CSF
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microglia
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major CNS phagocyte; major site of HIV infection in brain
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glucose-lactate shuttle
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astrocytes take up glucose, convert to lactate to release for neurons
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radial glia
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guide newborn neurons to proper destination
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Astrocytes and potassium
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act like sponges to take up extracellular K to prevent depolarizing neurons and excitotoxicity
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Glia and glutamate
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Glia can take up glutamate (major excitatory NT of CNS) to terminate synaptic transmission. Convert to glutamine and release for neurons to take up and recycle back to glutamate.
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excitotoxicity
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NT are damaged and killed by excessive stimulation by neurotransmitters or ions.
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glial fibrillary acidic protein
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marker of astrocytic activity
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bipolar neuron
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single axon/dendrite; located in sense organs
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multipolar neuron
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single axon/many dendrites
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pseudounipolar
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cell's single process branches into axon/dendrite. located in spinal, cranial ganglia.
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dendrites
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receive stimuli and convert signal into electrical impulses transmitted to soma. can often receive stimuli from many neurons.
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cell body
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prominent nucleus w/ euchromatin, large nucleolus. RER and free ribo form Nissl bodies in cytoplasm. Neurofilaments and microtubues. Axon hillock lacks Nissl bodies but has many filaments.
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axons
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conduct impulses away from soma; vary in diameter and length. No RER in cyto.
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satellite cells
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PNS, support and protect
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multiple sclerosis
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mos common demyelinating disease; multiple areas of myelin lost in CNS; weakens lower extremities. disturbs visual, sensory.
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GBS
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acute inflammatory demyelinating disease of peripheral nerves. ascending muscle weakness and paralysis (moves up). most recover.
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epineurium
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dense fibrous CT forms external coat of nerves
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Perineurium
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dense CT surrounding a bundle of nerve fibers; inner surface is flattened epithelials joined by TJ
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endoneurium
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thin layer of reticular fibers (made by schwann) surrounding individual nerve fibers
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Regeneration of neurons
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death to cell body = irreversible; damaged axon can slowly regenerate.
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white matter
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mostly myelinated axons
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gray matter
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cell bodies, unmyelinated axons
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cerebral cortex
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thin layer of gray matter on surface of cerebral hemispheres. functions in memory, learning, integrating of signals.
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purkinje cells
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highly branched dendrites (tree-like) in cerebellar cortex
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Meissner's corpuscles
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small encapsulated receptor in dermis; single layered CT capsule enveloping nerve terminal and its Schwann cell. Fine touch, rapid-adapting. myelinated axon.
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Pacinian Corpuscle
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large, Multi-layer encapsulated receptor in dermis, joints, mesenteries. pressure, touch, vibration. looks like an oyster. myelinated axon, rapid-adapting.
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Free nerve endings
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Unencapsulated, unmyelinated terminations in skin around hair follicles and trachea receive pain and temp info.
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Ruffini's endings
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Large encapsulated receptors in dermis and joints - branched fibers all within capsule. Pressure and touch. myelinated, slow-adapting
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muscle spindle
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stretch receptor in muscle cells. modified muscle cells.
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Sensory ganglias
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contain pseudounipolar cell bodies. spinal ganglia: DRG; cranial nerve ganglia: Trigeminal, geniculate, spiral, vestibular, superior and inferior of IX, and superior and inferior of X
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Cell bodies in sensory ganglia
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circular shape, large spherical nuclei, nissel bodies in cytoplasm, surrounded by satellite cells. cell bodies usually in periphery to make room for myelinated fibers
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Sympathetic ganglia
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Cell bodies of neurons smaller and more irregular in shape. more uniformly distributed than in sensory ganglia, Fewer satellite cells.
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PS ganglia
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found in walls of organs, often as a plexus. clusters of neurons are smaller than symp.
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Auerbach's plexus
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innervates smooth muscle wall of the GI tube
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layers of the cortex
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Molecular layer (mainly neuroglia)
External granular layer (granule cells) External pyramidal layer (pyramidal cells and granule cells) Internal granular layer (granule cells) Internal pyramidal layer (pyramidal cells) Multiform layer (various cells including Martinotti cells) |
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layers of cerebellar cortex
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Molecular layer (stellate cells, basket cells, dendrites of Purkinje cells)
Purkinje cell layer (Purkinje cells) Granular layer (granule cells) |
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electrical synapse
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gap junction allows passive ion flow. minimal transmission delay; allows synchrony btw groups of neurons or glia.
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Chemical synapse
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Uses a neurotransmitter, can be excitatory, inhibitory or modulatory
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excitatory chemical synapse
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depolarizes post-synaptic cell; usually increases permeability to Na or Ca or inactivation of K channel
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inhibitory chemical synapse
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hyperpolarizes post-synaptic cell, usually increases perm to K
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What makes chemical synapses slower than electric
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time for Ca channels to open, changing conformation of snare complex, fusion of vesicle with cell membrane
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Fast chemical synapse
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Ionotropic, ligand-gated ion channel. Excitatory usually increases Na perm; inhibitory usually hyperpolarizes (GABA and Glycine increase Cl perm)
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Slow chemical synapse
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Metabotropic - GPCR. receptor activates a 2nd messenger to change ion permeability.
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Metabotropic activation and termination
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NT binds to receptor, G-alpha trades GDP for GTP. alpha subunit dissociates, then beta/gamma subunit dissociates. G proteins interact w/ effector that changes ion perm. Hydrolysis of GTP causes receptor to return to resting conformation
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Adenylyl cyclase
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cAMP, PKA
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Phospholipase C
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IP3 and DAG
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Termination of synaptic transmission
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active reuptake of NT by neurons/glia; passive diffusion out of cleft, receptor desensitization
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Ach
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Used by pregang Symp neurons and pre/post PS neurons.
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Glutamate
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major excitatory NT of CNS
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GABA
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major inhibitory NT of CNS
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Glycine
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major inhibitory NT of spinal cord/brainstem
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Catecholamines
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Dopamine, NE, Epinephrine (NE/E are key excitatory NT's of symp)
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Serotonin
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monoamine
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Neuropeptides
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made from AA in cell body, packaged into vesicles and transported to nerve terminal. Ex: endorphin
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Key excitatory NT's
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glutamate, ACh, serotonin
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Key inhib
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gaba, glycine
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Merkel's disk
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non-encapsulated nerve ending in dermins; small, slow-adapting, unmyelinated.
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A alpha axon
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largest diameter, myelinated, deals w/ proprioceptive info
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A beta axon
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smaller, myelinated, deals w/ mechanoreception. involved in 1st pain (sharp) response
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A delta axon
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thinly myelinated, medium diameter, nociception. 1st pain (sharp) response
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C axon
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small, unmyelinated, innocuous temp, itch, nociception. involved in 2nd pain (burning) response
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