Choose the best option for each part and please explain why it is correct. Part
ID: 3519071 • Letter: C
Question
Choose the best option for each part and please explain why it is correct.
Part 1: The slow release of the products of ATP hydrolysis from myosin in relaxed muscle is important because it ___
a. allows ATP to reform from ADP and phosphate
b.limits energy use
c. promotes myosin phosphorylation
d. stabilizes the 45 degree state
Part 2: The fastest shortening velocity for a skeletal muscle would occur when the load is ___________ the maximum force the muscle can generate.
a. one-quarter of
b. one-third of
c. one-half of
d. equal to
Part 3: The graph below shows the active and passive length-tension relationships. The passive tension curve is primarily determined by the compliance of __________
a. the acto-myosin bond
b. titin
c. thick filament
d. thin filament
Normal operating range total force passive force 50 active force 1.0 2.0 u Length (proportion of resting length)Explanation / Answer
Part1) stablizes the 45 degree state
As long as ATP is available to drive the cross- bridge cycling and pulling of action strands by myosin, the muscle fibres will continue to shorten to an anatomical limit.
Part2) the fastest shortening velocity for a skeletal muscle would occur when the load is equal to the maximum force the muscle can generate.
Part3) length-tension curve
Isometric tension(ordinate) is plotted against muscle length( abscissa) expressed as a fraction of resting muscle length, 1.0. the muscles's elasticity resists stretch, causing tension that follows the dotted curve, this is passive tension. When the muscle's length is fixed at a value on the abscissa and then it is stimulated to contract, it develops tension that lies on dashed curve. This is the total tension or the sum of passive tension and developed tension. The difference (solid curve) between the dashed and dotted curves is the tension developed by the muscle when it contracts. This is maximum at the resting length.