| Term | Definition |
|---|
| Action potential (AP) | all or none, increased amplitude or duration dosen't change strength |
| Subthreshold | current below needed amplitude to create AP |
| Resting potential | difference in elec. potential across cell membrane when info not being transmitted |
| -70mV | charge maintained by Na+ / K+ pumps. neg. charged ions trapped in cell |
| Depolarization | membrane potential becomes less neg. than resting potential |
| -55mV | threshold level that will create AP. Na+ channels open and Na+ moves inside to make cxell more postively charged |
| Opening of valtage gated Na+ channels - pulling Na+ into cell | Depolarization |
| Na+ channels close - K+ channels open, K+ pushed out of cell | Repolarization |
| Absolute refractory period | when membrane depolarized not possible to create another AP |
| Relative refractory period | during short hyperpolarization - stronger than normal stimulus required for AP |
| AP propagation / conduction | AP triggered in adjacent nerves along the neuron |
| Physiological propagation | occurs in one direction |
| Estim propagation | can occur both directions but effects only seen one way |
| sensory nerves | afferent - goes to brain |
| motor nerves | efferent - goes to muscles |
| Propagation speed | dependent on size, myelination, and nodes of Ranvier |
| Larger myelinated nerves | faster propagation |
| Strength - Duration Curve | minimum amount of elec. current required to depolarize and produce AP |
| Sensory nerves strength - duration curve | lower current amplitude and shorter pulse duration required |
| Motor nerves strength - duration curve | higher amplitude and longer pulses required |
| Pain transmitting C fibers strength duration curves | highest amplitude and longest pulses required |
| Acommodation | decrease response to same amplitude of nerve stimulation |
| Innervted muscle depolarization | contrat via depolarization of motor nerves |
| Denervated muscle depolarization | muscles contract due to depolarization of muscle cell membrane |
| Estim effects | subsensory -> sensory -> motor effects |
| Monophasic pulsed current | charge one way--charge in muscle when done |
| Biphasic pulsed current | most common, possible charge left -- symmetric or asymmetric |
| Polyphasic pulsed current | possible charge left, usually two one one side / one on the other |
| Symmetric Biphasic pulsed | even on each side -- no charge left |
| Asymmetris biphasic | uneven on each side -- possible charge left |
| Balanced asymmetric | area the same -- no charge left |
| Unbalanced asymmetric | area different -- charge left |
| purpose of waveform | tell what you are going to do -- pulsed / continous / monophasic / biphasic |
Combine with other sets
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