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20 Cards in this Set
- Front
- Back
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what do neurons communicate with?
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other neurons or effector cells; mediated by neurotransmitters
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what are glia cells?
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outnumber neurons by 10:1 and support the function of neurons
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what is the membrane potential of a resting cell?
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-70mV
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what is the concentration gradient of Na
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high outside, low inside; 150mM vs 15mM; poorly permeable membrane
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what is the concentration gradient of K
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high inside, low outside; 5 vs 140; membrane somewhat permeable
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what is the concentration gradient of Cl
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high out, low in 110vs 10; membrane somewhat permeable
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what are the properties of negatively charged proteins
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higher inside; not permeable at all
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what is the equilibrium potential
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membrane potential at which that equilibrium is reachd for a given ion (K:-90mV, Na:+60mV)
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what is the resting permeability closer to
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closer to K+ than Na+ because the membrane is 50x more permeable to K than Na
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what are graded potentials;
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decrement over space and time; sensory and synaptic potentials are graded
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how can multiple graded potentials add?
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if they occur close enough together in space or time (spatial or temporal); .1-1mm and 1-20msec
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what is an action potential
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change in membrane potential
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what is the absolute refractory period
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once voltage gated Na opens they become blocked for time so they cannot produce another action potential
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what is hyperpolarization
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because K stays open longer than Na, there is hyperpolarization at the end of an AP
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what is the relative refractory period
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harder for an AP during hyperpolarization
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what is threshold depolarization
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signal travels down without decreasing in strength
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what influences how long the cell stays above threshold
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# of action potentials generated
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what does mylination do
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increases speed that AP jumps along axon
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how does the AP travel with myelinated axons
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jumps from node of Ranvier to node; unmylinated conduct ~1m/sec; mylinated 50m/sec
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how does neurotransmitter release
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once AP invades nerve terminal; voltage gated Ca++ channels open; this increase cause NT release by exocytosis;
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