Question

Answer the following in complete sentences. Where asked, provide a sketch. If the sketch is a cart or graph, include titles and units for the axes.

What is the significance of the length–tension relationship for a skeletal muscle fiber? Sketch the relationship.

Describe a lever system in the body that operates at a mechanical advantage and one that operates at a mechanical disadvantage. Sketch each system showing the applied loads, the resulting force and fulcrum

Define each of the following terms: concentric isotonic contraction, eccentric isotonic contraction, and isometric contraction. Include a separate sketch for each contraction.

Answer 1

Since you have posted multiple long answer questions, I am going to answer first one. I hope it helps. Thanks

1. Tension in muscles is composed of the forces generated by many cross-bridge formations. It is basically the pulling of the actin filaments by myosin heads towards each other, this pulling then creates tension. The magnitude of the tension depends on the frequency of the stimulation and the initial resting length of muscle fibres. The active length-tension relationship reflects the degree of overlap between the actin and myosin filaments in a sarcomere. Too much or too little overlap leads to sub-optimal tension being developed but where the overlap is “just right” maximal tension is developed. The passive length-tension relationship reflects the presence of elastic elements within a sarcomere, which stretch and produce force with increasing length. The length tension relationship describes the force exerted by individual muscle fibers or muscles. It does not describe the torque exerted by a joint at different angles. This is called the torque-angle relationship.