Check off list for Lesson 20 Describe the three types of muscle tissue The three types of muscle tissue are skeletal cardiac and smooth Skeletal muscle operates under voluntary control to control body movement Skeletal muscle tissue is the ONLY muscle tissue that is part of the Muscular System Cardiac and smooth muscle operates under involuntary control Cardiac muscle is located in the heart and skeletal muscle is located in viscera and blood vessels Explain the function of skeletal muscle tissue There are six functions of skeletal muscle tissue 1 Produce skeletal movement under voluntary control 2 Maintain posture and body position 3 Support soft tissues by lining the abdominal wall and pelvic 4 Guard entrances and exits such as Sphincters in alimentary 5 Maintain body temperature via contractions shivering to cavity canal urethra produce heat nutrients needed 6 Store nutrients reserves muscle protein breaks down when Describe the connective tissue that covers skeletal muscles The connective tissue that covers skeletal muscles consists of three layers epimysium perimysium and endomysium Epimysium Exterior is made of a dense collagen layer Connected to deep fascia Separates muscle from surrounding tissues Consists of collage and elastic fibers 1 Perimysium Endomysium Surrounds muscle fiber bundles fascicles Contains blood vessel and nerve supply to fascicles Surrounds individual muscle cells muscle fibers Contains capillaries and nerve fibers contacting muscle cells Contains myosatellite cells stem cells that repair damage minimal repair ability How do they form tendons aponeuroses Skeletal muscle layers come together at the end of muscles and attach to bones the connective tissue attachment is called a tendon bundles or aponeuroses sheet Describe the characteristics of skeletal muscle cells Skeletal muscle cells are large in diameter and contain hundreds of nuclei Also they develop through the fusion of mesodermal cells myoblasts Why do they have multiple nuclei The development of skeletal muscle cells does not destroy nuclei and this this type of muscle tissue has 100s of nuclei What are the function of the sarcoplasmic reticulum and transverse tubule The sarcoplasmic reticulum stores calcium and the transverse tubule are a conduct electrical impulses from the surface of the cell to the terminal cisternae Describe the arrangement of the sarcomere The sarcomere is the contractile until of muscle fibers The alternating thick filaments A bands and thin filaments I bands make a visible pattern within myofibrils 2 REALLY KNOW UNDERSTAND THIS FIGURE DR SU MENTIONED IT OFTEN Explain how the myofilaments are arranged in the sarcomere Myofilaments are surrounded by the ER and consist of sarcomeres What are the different regions A band I band etc of the sarcomere and which myofilament is found there The components of the A band are m line h band and zone of over lap The M line is the center of the A band that ANCHORS thick filaments The H band is the area around the Mline that has thick filaments but NO thin filaments The zone of over lap is the A band minus the H band this region is where thick AND think filaments overlap The components of the I band are the Z lines and titin The z lines are the center of the I bands and they re located at the two ends of sarcomere Titin are strands of protein that freach from the tips of thick filaments to the Zline Titin function is to stabilize the filaments Describe the components of the thin and thick filaments The thick filaments are composed of bundles of myosin molecules and titin 3 The thin filaments are composed of f actin g actin nebulin and 2 regulatory proteins tropomyosin and troponin What is the function of these components Thick Thin Myosin molecules play a major role in contraction they consist on a head and tail The head reaches the nearest thin filament to bind myosin binding site the tail binds to other myosin molecules During contraction nyosin heads interact with actin filaments to form cross bridges Titin strands help keep thick and thin filaments aligned and restores sarcomere length once muscle relaxes when contraction is finished F actin is two twised rows of globular G actin their active sites bind to myosin Nebulin is a protein strand that runs along the length of F actin strands to hold them together Tropomyosin prevents the act myosin interaction at rest because it blocks the myosin binding sites found on the F actin strands Troponin binds tropomyosin to G actin and is controlled by Calcium When calcium binds it causes a change in 4 troponin conformation by exposing myosin binding sites on F actin strands Explain how the thick and thin filaments interact What is the sliding filament theory That during contraction the thin filaments slide past the thick filaments The thin filaments of the sarcomere slide towards the M line alongside thick filaments The Z lines move closer together which shortens the length of the sarcomere During this the width of the A band stays the same but the H I bands shrink Describe the neuromuscular junction and excitation contraction coupling The neuromuscular junction is the connection between a neuron and a muscle fiber Excitation contraction coupling requires the myosin head to be cocked into position once an action potential reaches a triad Ca is released and contraction is triggered Which neurotransmitter is released by the motor neuron 5 ACh is released into the synaptic cleft which results in an action potential in the muscle fiber How does the muscle cell respond The muscle fiber cell responds by releasing calcium from the SR into the sarcoplasm which triggers contraction 6 Check of List for Lesson 21 Describe the events that occur at the neuromuscular junction during the generation of an action potential at the sarcolemma 7 Describe the steps to excitation contraction coupling 8 1 Neural Control 2 Excitation A skeletal muscle fiber contracts when stimulated by a motor neuron at a neuromuscular junction The stimulus arrives in the form of an action potential at the axon terminal The action potential causes the release of ACh into the synaptic cleft which leads to excitation the production of an action potential in the sarcolemma 3 Release of Calcium Ions This action potential travels along the sarcolemma and down T tubules to the triads This triggers the release of calcium ions from the terminal cisternae of the SR 4 Contraction Cycle Begins The contraction cycle begins when the calcium
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