The contraction of a striated muscle fiber occurs as the sarcomeres, linearly arranged within myofibrils, shorten as myosin heads pull on the actin filaments. Myosin light chain kinase (MLCK) is activated Muscular Levels of Organization | Anatomy and Physiology I | | Course Hero Each nucleus regulates the metabolic requirements of the sarcoplasm around it. The release of calcium ions initiates muscle contractions. Test your knowledge about the types of muscle tissue in our custom quiz that covers all of these 3 topics: Types of muscle cells: want to learn more about it? (b) The myosin head is attracted to actin, and myosin binds actin at its actin-binding site, forming the cross-bridge. It ultimately causes death due to respiratory failure, and those afflicted do not usually live past their 20s. Flashcards - Chapter 9 Muscles and Muscle Tissue (TB) - FreezingBlue In contrast, cells lining the inside of the small intestine divide frequently. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell cause the entire cell to appear striated. EXSP 1010: Week 2 (Muscle Tissues: An Overview) Labster These muscle cells contain long filaments called myofibrils. (a) What are T-tubules and what is their role? After giving it some thought, sketch your idea of the distribution of gas velocity, pressure, temperature, and entropy through the inside of a shock wave. myosin and actin The names of the various sub-regions of the sarcomere are based on their relatively lighter or darker appearance when viewed through the light microscope. -structural proteins: maintain proper myofilament alignment and fiber stability (EX. Aerobic respiration is the breakdown of glucose or other nutrients in the presence of oxygen (O2) to produce carbon dioxide, water, and ATP. Referring to the karyotype below, it is clear that each chromosome pair is present and of relatively equal length. This energy is expended as the myosin head moves through the power stroke, and at the end of the power stroke, the myosin head is in a low-energy position. The sarcomeric subunits of one myofibril are in nearly perfect alignment with those of the myofibrils next to it. In doing scientific exploration, scientists found that an electrical current will stimulate a muscle cell, even if the cell is not in a living animal.