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Neuro Gold


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What are the forces acting on ions in solution?
Chemical: diffusion
Electrical: ions have repulsive and attractive forces
3 factors that determine the basis of membrane potential
combo of physical (chemical & electrical) and biological (semi-permeable membrane)
the measure of ease with which charge will flow in a system.

Reciprocal of Ohns
Ohm's Law would be: V = I/g
Negative current vs. Positive current
Negative current = positive charges moving in
Positive current = positive charges moving out
Inward current vs. outward current
Inward current: positive ions moving into the cell
Outward current: positive ions moving out of the cell
Driving force
Vm - Veq

m=membrane potential
eq=equilibrium potential
Equation for current flow
I = g * (Vm-Veq)

where g is conductance
Intracellular and Extracellular Concentration of K+
intra: 140
extra: 5
Intracellular and Extracellular Concentration of Na+
intra: 5-15
extra: 145
Intracellular and Extracellular Concentration of Cl-
intra: 4-30
extra: 110
Intracellular and Extracellular Concentration of Calcium
intra: 0.0001
extra: 1-2
very highly regulated
Definition of threshold
the potential at which inward Na+ current matches outward K+ current.
3 factors that influence PEP (passive electrical properties, aka cable properties)
internal resistance
membrane resistance
membrane capacitance
absolute refractory period
period of time during which it is not possible for a neuron to fire another action potential.
relative refractory period
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.
what is membrane capacitance?
the ability of the membrane to store charge.
myelination in CNS vs. PNS
CNS = oligodendrocytes
PNS = schwann cells
2 ays in which myelination speeds conduction velocity
1) increase MEMBRANE resistance
2) decrease capacitance-- it increases the charge separation
CA2+ ATPase
Removes Ca2+ from the cytosol pumping it into intracellular stores.
Electrogenic Pump
a pump that contributes to the resting membrane potential
"Silent," "Mechanically Insensitive" nociceptors
Sensitized by inflammatory mediators
Type I AMHs
Type I Adelta mechano-heat nociceptors

delay before firing, but once started, continue to fire
Type II AMHs
Type II Adelta mechanoheat nociceptors

fire immediately and stop firing pretty quickly
Efferent role of nociceptors
1) axons reflex
2) axonal coupling
3) antidromic action potentials

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