For a muscle cell to contract, the sarcomere must shorten. However, thick and thin filaments—the components of sarcomeres—do not shorten. Instead, they slide by one another, causing the sarcomere to shorten while the filaments remain the same length. The sliding filament theory of muscle contraction was developed to fit the differences observed in the named bands on the sarcomere at different degrees of muscle contraction and relaxation. The mechanism of contraction is the binding of myosin to actin, forming cross-bridges that generate filament movement.
|When (a) a sarcomere (b) contracts, the Z lines move closer together and the I band gets smaller. The A band stays the same width and, at full contraction, the thin filaments overlap.|
Complete the tasks on the list below:
- Go to this page, http://cnx.org/contents/GFy_h8cu@10.53:t8m3ArRs@6/Muscle-Contraction-and-Locomot, Scroll down to the section titled, Sliding Filament Model of Contraction. Read from their to the bottom of the page.
- The Qr code(s) on the page take you to this (these) resources
- Use the Glossary at the bottom of the page to help with the vocabulary for this week
- Use the Review Questions and Free Response questions to check for understanding
Download for free at http://email@example.com