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44 Cards in this Set
- Front
- Back
absolute refractory period
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time immed after the action potential when sodium gates close ad the membrane cant produce another action potential (also prevents current from moving backwards)
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action potential
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rapid depolarization followed by slight hyperpolarization. increase from -70mV to -55mV (threshold) then beyond - opens voltage gated Na+ and K+, propagates down axon at same level
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active transport
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protein mediated process that expends energy to pump chem from blood to the brain (ex: happens in blood brain barrier w/ glucose)
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afferent axon
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("a" admission) neuron that brings sensory info to (the CNS), every sensory neuron is afferent from the nervous system
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all-or-none law
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either an action potential will happen or it wont - electrical gradient must reach threshold in order for it to happen. size and intensity of AP are independet of the size of stimulation
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astrocyte
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star shaped glial cell. wraps around presynaptic terminals helps synchronoze activity by taking up chem released by axon and sending them back, also helps in waste removal when neurons die, and helps regulate blood flow to the brain
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axon
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thin fiber that extend form cell body. carries information from cell body (often myelinated)
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axon hillock
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at the "top" of the axon - where an action potential starts (after rcvng info from cell body)
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blood-brain barrier
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keeps harmful chemicals and viruses from reaching the brain, but also keeps useful meds (ie chemotherapy) from brain. O2, CO2 diffuse, glucose, A Acids vitamins , etc need active transport to reach brain
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cell body, or soma
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contains nucleus, ribosomes, mitochondria, neural membrane - neural membrane uniquely specialized for neural functions
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concentration gradient
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process where molecules travel from Hi to Low concentration area in order to reach equilibrium
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dendrite
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branches (covered w synaptic receptors) used to rcv info from other neurons
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dendritic spine
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increase surface area allowing more info to be passed on
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depolarization
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process where inside (of neural membrane) becomes more positive. from -70mV resting, to -55 threshold, if thrshold reached action potential is possible
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efferent axon
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("e" exit) carries info away from the CNS to motor neurons / muscles. every motor neuron is efferent from the nervous system
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electrical gradient
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diff in + / - chargs across membrane (ie: + attracted to -)
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glia
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most numerous type of neuron. DOES NOT conduct impulses to other cells - types: astrocytes,microglia, oligodendricytes (CNS) schwann (PNS), radial glia guide migration @ embryonic stage
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graded potential
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membrane potential that varies in magnitude (ex NT's from synapse cause graded potential in dendrites) gradually decreases in intensity
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hyperpolarization
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increased negative charge (drops below -70mV resting potential) in AP due to K+ leaving and Cl- entering
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interneuron
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cell who's axon and dendrites contained within a structure (interneuron in thalamus has axon and dendrite contained in thalamuc
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local anesthetic
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attach to Na+ channels and block it from entering cell, therefore blocks action potentials (that could signal pain messages) scorpion venom keeps Na+ open therefore too much Na+ comes and / toxic
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local neuron
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small neuron w small or no axon, therefore they exchange info though graded potential (astrocytes and glial cells act like local neurons)
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membrane
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structure that separates inside from outside of cell structure.phospholipid bi-layer of neural membrane is only semi permeable, voltage or chem gated protein channels allow certain ions to flow in/out at certain rate
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microglia
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small glial cell that remove waste material and microorganisms from the CNS
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mitochondrion
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structure w/in neuron (soma and axon) that performs metabolic activity that provides "fuel" (ATP) for the cell
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motor neuron
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efferent neuron / conducts impulses from its soma in the sp cord to muscle or gland
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myelin / myelin sheath / myelinated axon
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insulated material (oligo in CNS, schwann in PNS), sheath conducts impulses faster via saltitory conduction
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neuron
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cell that rcvs and xmits info to other cells by conducting electro-chemical impulses
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node of Ranvier
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short unmyelinated spaces btwn myelin segments - AP jumps to nodes (Na+ channels are open at the nodes) and propagates
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nucleus
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2 defs: structure within cell that cotains chromosomes, & cluster of cell bodies in the CNS
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oligodendrocyte
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glial cell that produced myelin sheath in the CNS
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polarization
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the electrical gradient across a membrane.
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presynaptic terminal
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tip of the axon. NT's are released to cross synapse and activate receptors on the postsynaptic terminal (of dendrite)
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propagation of the action
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happens via saltitory conduction. AP doesnt vary in "strength"
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relative refractory period
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period after absolute refractory period when K+ gates are open wider than usual requiring a stronger than usual stimulus to create AP
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resting potential
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-70mV, electrical potential across membrane when cell is not being stimulated. inside is more negative, due to negatively charged proteins
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ribosome
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located in the soma - ribosomes synthesize new protein molecules, proteins provide bldg materials for the cell and facilitate various chemical rxns
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saltatory conduction
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how the AP travels down myelinated axon - it jumps from node to node following the flow of positive ions (Na+)
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Schwann cell
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glial cells that produce myelin sheaths on (some) axons in the PNS
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selective permeability
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the ability for some chemicals to pass freely across cell membrane (ex: blood brain barrier) (ex: Na+ must be pumped in but Cl- can diffuse slowly)
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sensory neuron
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afferent neuron, takes sensory info TO a structure, ex: if hand is burned, afferent neuron takes info from nerve on hand to dorsal side of sp cord
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sodium-potassium pump
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after AP / absolute refractory period, it pumps (3) Na+ ions out and (2) K+ ions in. pump is used to restore resting potential/homeostasis
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threshold of excitation
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level of depolarization at which stimulation beyond this point will produce massive depolarization (AP), Na+ channels open and Na+ rushes in (further depolarizing), AP can only happen if depolarization reaches threshold
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voltage-activated channel
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channels in the membrane that depend in voltage differences to open /close them (ex Na+ channels are voltage gated)
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