4a Define summation as it relates to muscle contraction b Ex

4a- Define summation as it relates to muscle contraction, (b) Explain how increasing the frequency of stimulation affects the amount of force generated by a muscle and (c) What causes fused tetanus?

Solution

a. A skeletal muscle is stimulated and an immidiate second stimulus is applied before relaxation is complete. This gives instant 2nd stimulus in the muscle called Summation,

b. A second contraction, which develops a greater tension, is fused to the first contraction. A possible explanation may be that Ca2+ remains from the previous contraction and together with additional Ca2+ from the second stimulus constitutes moreactivator Ca2+ than would be available if relaxation had been incomplete.

C. Over summation leads to Tetanus: If the stimulus is repeated at a sufficiently high rate, the muscle will not relax between each stimulus but rather will remain in a contracted state.