Peter was holding a Human Physiology textbook that weighs about 4lbs with his non - writing arm for one minute. His elbow remained exactly at a 45° isometric position. He did not complain of any muscle fatigue or muscle weakness. a) i. Is the number of activated motor units stay the same while he was holding the book for two minutes? (0.5 pt) ii. Why? (0.5 pt) Increasing the period Peter is holding the texting will only cause the motor units to fire more frequently to keep the muscles from relaxing. b) i. Are the same motor units activated while he was holding the book for two minutes? (0.5 pt) ii. Why? (0.5 pt)

Question

Physics

Amy Wilson

31 December, 17:07

Peter was holding a Human Physiology textbook that weighs about 4lbs with his non - writing arm for one minute. His elbow remained exactly at a 45° isometric position. He did not complain of any muscle fatigue or muscle weakness. a) i. Is the number of activated motor units stay the same while he was holding the book for two minutes? (0.5 pt) ii. Why? (0.5 pt) Increasing the period Peter is holding the texting will only cause the motor units to fire more frequently to keep the muscles from relaxing. b) i. Are the same motor units activated while he was holding the book for two minutes? (0.5 pt) ii. Why? (0.5 pt)

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Taniya Franklin · Answer 1

a

When peter held the book for one minute the rate at which motor unites are fired increase steeply but as the duration increases the increese in the rate at which it is being fired becomes linear so the number of activated motors stay the same but are being activated at a more rapidly

b

The same motors are activated whilest he is hold the book for 2 minutes this is because for peter to hold the book in one fixed position one specific motor units need to be activated

Note changing the motor unites would change the positon of the hand