electrical stimulation for muscle contraction

Question 1

what happens after the action potential arrives at axon terminal of motor neuron?

Answer 1

voltage gated Ca2+ channels open. Ca enters the axon terminal moving down its electrochemical gradient.
Ca entry causes ACh to be released by exocytosis
ACh diffuses across the synaptic cleft and binds to its receptors on the sarcolemma
ACh binding opens ion channels in the receptors that allow simultaneous passage of Na+ into the muscle fiber and K+ out of the muscle fiber. More Na+ ions enter than K+ ions exit, which produces a local change in the membrane potential called the end plate potential
ACh effects are terminated by its breakdown in the synaptic cleft by acetylcholinesterase and diffusion away form the junction

Question 2

T/F: muscle contractions produced by electrical stimulation are identical as physiological contractions

Answer 2

False they are not identical

Question 3

what can electrical stimulated contractions do?

Answer 3

strengthen muscle
improve muscle endurance
improve cardiovascular health
prevent muscle atrophy
reduce spasticity
help restore function

Question 4

what is the order or recruitment of a muscle when it is physiologically stimulated?

Answer 4

slow twitch type 1 are activated first. a normal voluntary contraction- the progressive recruitment of small, slower motor units followed by larger sized, faster motor units to become engaged in the task

Question 5

what is the order or recruitment of a muscle when it is electrically stimulated?

Answer 5

fast twitch type 2 muscle fibers

Question 6

what is the gradation of contraction of a muscle when it is physiologically stimulated?

Answer 6

gradually increase force in smoother manner

Question 7

what is the gradation of contraction of a muscle when it is electrically stimulated?

Answer 7

rapid/jerky recruitment because all motor units under pad fire once stimulated

Question 8

describe type 1 muscle fibers

Answer 8

smaller, slow twitch, produce less force contraction, more resistance to fatigue and atrophy

Question 9

describe type 2 muscle fibers

Answer 9

larger, faster twitch, produce more force and quicker contraction, fatigue rapidly, prone to weakening and atrophy with disuse

Question 10

what is the clinical implication of difference for electrically stimulated fast twitch type 2 muscle fibers?

Answer 10

can very effectively strengthen muscle fibers that have been atrophied from disuse
more fatiguing (longer rest times should be provided)
patients should perform physiologic contractions with electrically stimulated contraction to optimize recruitment and functional integration