task 4+5

Question 1

what is the meaning of superposition (temporal summation)?

Answer 1

if a fiber is stimulated repeatedly before the previous calcium transient has finished, the new stimulus elicit additional calcium reales thus contraction increases.

(intracellular calcium has no time to be removed between stimuli)

Question 2

how to examine superposition?

Answer 2

the muscle is stimulated with twin stimuli (two stimuli). begin with 200 ms “delay” (between stimuli) and then decrease in 25 ms steps

Question 3

what is the meaning of complete tetany?

Answer 3

when contraction gets stronger and stronger until the muscle doesn’t relax but shows continous spasm

Question 4

incomplete spasm

Answer 4

when the different contractions can still be distinguished.

Question 5

How to examine muscle fatigue in humans?

Answer 5

The subject should press the hand dynamometer with maximal force for 10 sec, then relax for 2 sec. x 5 times