Transcript Muslces
Muslces Group 4 Classification Agonist: prime mover Antagonist: Synergist: Fixator: mover reverses agonist prevents rotation stabilizes the origin of the prime Naming (LADSNOR!) Direction of the muscle fibers Ex) transverse, rectus, oblique Relative size of Ex) major, minor muscles Location Number and location of origin Shape Action of the muscle Ex) extensor, flexor Origin and Insertion Origin: immovable end Insertion: movable end Characteristics Muscle cells are elongated Contractions are due to the movement of microfilaments Structure (skeletal muscle) Structure (cont.) From outermost to innermost Muscle>Fascicles>Muscle fibers>Myofibril>Thick and thin filaments Fascia>Epimysium>Perimysium>Endomysiu m Tissue layers of a skeletal muscle Fascia: covering the whole muscle Epimysium: lies beneath the fascia Perimysium: separates cells of fascicle Endomysium: fibers separates individual muscle Fascicle Collection of muscle fibers Covered by blood vessels and axon of motor neurons Each muscle fibers is separated by endomysium It is surrounded by sarcolemma Contains nucleus and sarcoplasmic reticulum Each muscle fibers is composed of myofibril Myofibril & Sarcomere Sarcomere It is a repeating pattern formed by striations Sarcomere (cont.) Troponin: protein that works with tropomyosin to block muscle contraction until calcium ions are present Transverse tubule: set of membranous channels that contain extracellular fluid Smooth muscle It is shorter than skeletal muscle, and has single centrally located nuclei It It lacks troponin alternates between a state of relaxation and contraction Cardiac muscle Composed of striated cells, containing a single nucleus It has a well developed sarcoplasmic reticulum Its transverse tubule is larger than skeletal muscle’s Contraction Acetylcholine(ACh) is the neurotransmitter that contracts skeletal muscles ACh binds with receptors on the motor endplate, which causes muscle impulse Calcium ions diffuse from sarcoplasmic reticulum to sarcoplasm and binds to troponin Contraction (cont.) Tropomyosin moves, which allows actin and myosin to link Actin is pulled to the center of the sarcomere, which allows muscle fibers to shorten Threshold Respiration Anaerobic breaks down glucose and releases ATP Aerobic requires oxygen to produce ATP Oxygen debt When cellular respiration is not able to sustain the muscle, lactic acid diffuses into the blood stream This creates an oxygen debt, that must be repaid later Muscle fatigue When a muscle loses its ability to contract Most likely occurs from accumulation of lactic acid Types of contraction