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24 Cards in this Set
- Front
- Back
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What are the forces acting on ions in solution?
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Chemical: diffusion
Electrical: ions have repulsive and attractive forces |
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3 factors that determine the basis of membrane potential
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combo of physical (chemical & electrical) and biological (semi-permeable membrane)
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Conductance
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the measure of ease with which charge will flow in a system.
Reciprocal of Ohns Ohm's Law would be: V = I/g |
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Negative current vs. Positive current
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Negative current = positive charges moving in
Positive current = positive charges moving out |
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Inward current vs. outward current
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Inward current: positive ions moving into the cell
Outward current: positive ions moving out of the cell |
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Driving force
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Vm - Veq
m=membrane potential eq=equilibrium potential |
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Equation for current flow
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I = g * (Vm-Veq)
where g is conductance |
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Intracellular and Extracellular Concentration of K+
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intra: 140
extra: 5 |
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Intracellular and Extracellular Concentration of Na+
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intra: 5-15
extra: 145 |
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Intracellular and Extracellular Concentration of Cl-
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intra: 4-30
extra: 110 |
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Intracellular and Extracellular Concentration of Calcium
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intra: 0.0001
extra: 1-2 very highly regulated |
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Definition of threshold
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the potential at which inward Na+ current matches outward K+ current.
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3 factors that influence PEP (passive electrical properties, aka cable properties)
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internal resistance
membrane resistance membrane capacitance |
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absolute refractory period
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period of time during which it is not possible for a neuron to fire another action potential.
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relative refractory period
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a period following the absolute refractory period during which it is possible for a neuron to fire another action potential, but only if suprathreshold stimuli apply.
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what is membrane capacitance?
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the ability of the membrane to store charge.
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myelination in CNS vs. PNS
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CNS = oligodendrocytes
PNS = schwann cells |
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2 ays in which myelination speeds conduction velocity
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1) increase MEMBRANE resistance
2) decrease capacitance-- it increases the charge separation |
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CA2+ ATPase
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Removes Ca2+ from the cytosol pumping it into intracellular stores.
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Electrogenic Pump
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a pump that contributes to the resting membrane potential
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"Silent," "Mechanically Insensitive" nociceptors
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Sensitized by inflammatory mediators
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Type I AMHs
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Type I Adelta mechano-heat nociceptors
delay before firing, but once started, continue to fire |
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Type II AMHs
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Type II Adelta mechanoheat nociceptors
fire immediately and stop firing pretty quickly |
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Efferent role of nociceptors
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1) axons reflex
2) axonal coupling 3) antidromic action potentials |
