BSC-1005 Lecture Notes - Lecture 9: Endoplasmic Reticulum, Skeletal Muscle, Cardiac Muscle
Document Summary
**antagonisic pairing of skeletal muscles around joints is an organizing principle of the musculoskeletal system. Skeletal muscles typically occur in antagonisic pairs because muscles only shorten acively. Relaxed muscles re-lengthen when the antagonist muscle contracts. Muscle type: skeletal muscle, cardiac muscle cells are striated (have sarcomeres) Increased ca(2+) concentraion acivates cross-bridge cycling in all types of muscle details vary among the 3 major types of muscle. Origin of ca(2+) transients in striated muscle: sarcoplasmic reiculum: storage place for ca(2+, ca(2+) acivates thin ilament (acin), allowing cross-bridge cycling. Striated muscle: acin and myosin ilaments are arranged in highly organized arrays (sarcomere: acin thin ilament, myosin thick ilament. Striated muscle contracts when sarcomere shortening due to ilament sliding: sarcomere is the basic unit of contracion in striated muscles. Ca(2+) acivates contracion by changing the structure of thin ilaments in striated muscles: thin ilaments (acin) in striated muscles have accessory proteins, tropomyosin and troponin, that allow cross-bridge cycling when ca(2+) binds.
