S+P Exam 3: Mechanical models

Cross-Bridge Models

Series arrangement, Parallel arrangement

Fiber Models

parallel muscles, pennate muscles

In fiber models The force generated by a myofibril is equal to…

the force generated by one sarcomere of the fibril

in fiber models Shortening of the fibril is equal to…

The summed shortening of the sarcomeres

In parallel muscles force generated by the muscle will be equal to…

the sum of the individual fibers in parallel at a given length

In parallel muscles the amount of shortening will be dependent on…

the length of the individual fibers and whether there are fibers in series

In pennate muscles the geometry of the muscle affects the….

relationship of fiber and muscle length changes

In pennate muscles fiber force is exerted in…

a different direction than the muscle force

In pennate muscles the muscle fiber shortening may be accompanied…

by an increased fiber angle (which would enhance the amount of muscle shortening, and compensate for having a fiber angle)

The length range of active force produced is affected by muscle architecture determined by:

changes of fiber length(which is highly dependent on # of sarcomeres in series), changes in fiber angle, changes in aponeurosis angle

The Hill model includes

CE, SEC and PEC

In the hill model force exerted by the CE should be…

equal to force maintained in the SEC

In the hill model lengthening or shortening of CE and SEC must be…

added to obtain total length change of muscle complex

In the hill model isometric contraction results in…

shortening CE, lengthening of SEC, with no change in muscle complex length

In the hill model decreased force below optimum CE length would be accompanied by…

a decrease in SEC length

In the hill model shortening velocity of muscle complex is equal to…

the sum of both shortening velocities of CE and SEC

In the hill model cross bridges are not equivalent to CE because…

they contain elastic characteristics as well as contractile ones

In the hill model the SEC can also be found in…

cross bridges and 15% of elastic length changes are located intracellularly

In muscle model incorporating elastic tissues muscle length is made up of 2 components:

fiber length and aponeurosis projected onto muscle line of pull and because of this fiber length does not have to change as much to obtain a given muscle length change

In muscle model incorporating elastic tissues aponeurosis characteristics…

become more important and fiber characteristics become less important

In comparison to a single sarcomere, a muscle contraction with sarcomeres arranged in series will result in…

a greater change in muscle length and no change in force production

In comparison to sarcomeres arranged in parallel, a muscle contraction with the same # of sarcomeres arranged in series will result in…

a greater change in muscle length with a decrease in force production

Pennate muscles produce more force compared to

longitudinal muscles