11. T.S Skeletal Muscle
The sarcomere is the functional unit of a skeletal muscle cell. Each sarcomere is about 2.5 micrometers in length. It is made up of multiple myosin and actin filaments oriented in parallel. The actin and myosin filaments overlap in certain places creating several bands and zones. A Z disc forms the boundary of the sarcomere on either side. Thin actin filaments project in either direction off of a Z disc but do not cross the entire length of the sarcomere. They are almost 8 nm in diameter and have tightly bound regulatory proteins called troponin and tropomyosin.