BIO310H5 Lecture Notes - Lecture 4: Endoplasmic Reticulum, Sarcolemma, Titin
Document Summary
Skeletal muscle is made up of numerous bres. Sarcoplasmic reticulum: the modi ed endoplasmic reticulum (stores ca 2+ ) Each has myosin (thick) and actin (thick) laments. Large polymerized protein molecules that aid muscle contraction. Anatomy of skeletal muscle: sarcomere: structural and functional unit of the muscle, a band: region of the myo bril"s striation that has the darker appearance; also called the dark band. Corresponds to the entire length of the thick (myosin) lament: i band: light region of the myo bril"s striation. The length between 2 adjacent thick (myosin) laments. *gets narrower during contraction: h zone: lighter stripe in the center of the a band (dark region). Corresponds to the region between the thin (actin) laments. *widest when muscle is relaxed: z line: line to which the thin (actin) laments are attached. Extensions of the sarcolemma that associate with the terminal cisternae of the sr. Brings action potentials into interior of muscle bre.
