Agents - 3 - Muscle and Nerve Excitability

physical, thermal, chemical

physiological response to electrical current can be _______, _________, or _________

sodium Na, chloride Cl

in response to ES, sodium chloride splits into _________ and _________

cathode

sodium ions are attracted to the __________

anode

chloride ions are attracted to the ___________

easier

it is (easier/harder) to generate an action potential at the cathode

harder

it is (easier/harder) to generate an action potential at the anode

DIRECT

electrochemical effects (sodium & chloride) apply to _________ current

anode

the (anode/cathode) forms HCl

cathode

the (anode/cathode) forms NaOH

anode

the (anode/cathode) reaction is acidic

cathode

the (anode/cathode) reaction is alkaline

anode

the (anode/cathode) process is sclerotic

cathode

the (anode/cathode) process is sclerolytic

hardening

the anode has the effect of skin (softening/hardening)

softening

the cathode has the effect of skin (softening/hardening)

AAA vs CAB

• anode attracts acid

• cathode attracts basic

what’s an acronym to remember the electrochemical effects of direct current:

exchanged

“energy is neither created nor destroyed, but rather ________”

1-2 hrs

skin changes could occur within _____ of the session

tissue impedance

_________ is resistance of the tissue to the passage of electrical current flow

bone, fat, fascia

high impedance tissues:

nerve, muscle

low impedance tissues:

increases

impedance (increases/decreases) with edema, ischemia, scarring, and denervation

decreases

impedance (increases/decreases) with open wound and abrasions

• oily skin

• lotion

• makeup

• body hair

• calloused skin

• dry skin

items that may increase skin impedance:

F; DON’T shave right before

T/F: a patient can shave right before an estim treatment

70 mV

resting membrane potential is about ______

amplitude, duration

with sufficient _______ and ________, estim will cause the nerve to depolarize and generate an action potential

T, generally

T/F: the nerve is depolarizing, not the muscle directly

all or nothing

action potentials are an _____________ response

plot of strength (y), and duration (x)

what is an SD curve:

inversely

with the SD curve, intensity and duration are (directly/inversely) related

rheobase

the ________ is the minimum intensity capable of eliciting minimally detectable motor response

double rheobase

the _________ is used to account for the impedance of skin

chronaxie

the __________ is the time needed by a current, whose intensity is double the rheobase, to excite the nerve, accounting for skin resistance

inversely

chronaxie is (directly/inversely) related to excitability

less

the chronaxie of nerve fibers is (more/less) than the chromaxie of muscle fibers

biggest, lowest

the nerve fibers with the (biggest/smallest) diameter and (highest/lowest) resistance depolarize first

a-alpha, a-beta, a-delta, c

arrange these nerve types from biggest to smallest:

• a-beta

• c

• a-alpha

• a-delta

T

T/F: fibers closest to the electrode will be excited before fibers further away

F; FEEL before motor response

T/F: with estim, there will be a motor response before the pt feels the estim

sensory, motor, noxious

the levels of response to estim from first to last are _________, _________, then __________