ANAPHY

• skeletal muscles - attached to bones, striated, voluntary
• cardiac - located in heart, striated, involuntary
• smooth - located in blood vessels, hollow organs, non-striated, involuntary
• cell shapes: skeletal - single, very long, cylindrical
• cell shape: cardiac - branching chains of cells
• cell shapes: smooth - single, fusiform
• speed of contraction: skeletal - slow to fast; cardiac - slow; smooth - very slow
• functions of Muscular System - movement, maintain posture, respiration, production of body heat, communication, heart beat, contraction of organs and blood vessels
• contractility - ability of muscle to shorten forcefully or contract
• excitability - capacity of muscle to respond to stimulus
• extensibility - ability to be stretched beyond its normal resting length and still be able to contracts
• elasticity - ability to recoil to its original resting length after it has been stretched
• skeletal muscle is also called striated muscle
• skeletal muscle consitutes 40% of body weight
• some skeletal muscles attach to the skin or connetive tissue sheets
• skeletal muscle is also called striated muscle because transverse bands or striations
• epimysium - connective tissue sheath that surround each skeletal muscle
• fascicles - skeletal muscle subdivisions groups of muscle cells
• perimysium - surround the fascicle
• endomysium - surround each skeletal muscle cell
• muscle fiber - is cylindrical cell with several nuclei located at its periphery
• muscle fiber ranges in length 1 cm to 30 cm and are generally 0.15 mm in diameter
• sarcolemma (cell membrane) has many tubelike inward folds called transverse tubules or T tubules
• T tubules occur at regular intervals along the muscle fiber and extend into the center of the muscle fiber
• T tubules are associated with enlarged portion of smooth ER called the sarcoplasmic reticulum
• terminal cisternae - the enlarged portions in the T tubules
• T tubules connect the sarcolemma to the terminal cisternae to form a muscle triad
• sarcoplasm - the cytoplasm of a muscle fiber which contains many bundles of protein filaments
• myofibrils - bundles of protein filaments
• myofibrils consists of the myofilaments, actin and myosin
• sarcomere - the basic structural and functional unit of a skeletal muscle capable of contracting
• Z disks - form a network of protein fibers that serve as an anchor for actin myofilaments and separate one sarcomere from the next
• the organization of actin and myosin myofilaments gives skeletal muscle its striated appearance and give it the ability to contract
• the myofilaments slide past each other, causing the sarcomeres to shorten
• each sarcomere consists of 2 light staining bands separated by a dark-staining band
• I bands - light bands, consist only of actin myofilaments that extends toward the center of the sarcomere to the ends of the myosin myofilaments
• A bands - dark-staining bands that extends the length of the myosin myofilaments
• Actin myofilaments is made up of: actin, troponin, and tropomyosin
• troponin - molecules that have binding sites fo Ca2+
• tropomyosin - filaments block the myosin myofilaments binding sites on the actin myofilaments