Isometric Active Force Developed by Skeletal Muscle at Long Lengths

Question

Isometric active force developed by skeletal muscle at long lengths (greater than the rest length)
A) Is directly proportional to the overlap of thin and thick filaments
B) Depends on the number of cross-bridges
C) Depends linearly on the distance
D) Is a major evidence for the sliding filament hypothesis
E) All of the above

Accepted Answer

The isometric active force developed by skeletal muscle at lengths greater than the rest length is influenced by several factors: it is indeed directly proportional to the overlap of thin and thick filaments, as this overlap determines the number of potential cross-bridges that can form. The force also depends on the number of cross-bridges that can be formed, which is a function of the filament overlap. While the relationship between muscle length and force generation is not strictly linear across all lengths, within certain ranges, there can be a roughly linear relationship. Finally, these phenomena are key pieces of evidence supporting the sliding filament hypothesis, which posits that muscle contraction occurs as a result of thin and thick filaments sliding past each other, rather than either filament type changing length.