Muscular Physiology
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Muscular Physiology






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Muscular Physiology Muscular Physiology Presentation Transcript

  • Muscular Physiology
  • Explain how skeletal muscles provide movement, heat, and posture. Are all of these functions unique to muscles?Movement: Skeletal muscle contractions produce movements ofthe body as a whole (locomotion) or it its parts.Heat production: Muscle cells produce heat by the process knownas catabolism. Skeletal muscle contractions constitute one of themost important parts of the mechanism for maintaininghomeostasis of temperature.Posture: The continued partial contraction of many skeletalmuscles makes possible standing, sitting and maintaining arelatively stable position of the body while walking, running orperforming other movements.Contrability: is the ability to contract or shorten that allowsmuscle tissue to pull on bones and produce body movement.Extensibility is the ability to extend or stretch that allows musclesto return to their resting length after having contracted.
  • The characteristics of excitability is shared by what other system? Relate contractility and Extensibility to the concept of agonist and antagonist. Excitability is the ability to be stimulatedand it’s also known as irritability. Because skeletal muscle cells are excitable, they can respond to regulate mechanisms such as nerve signals.
  • What structures are unique to skeletal musclefibers? Which of the structures involved primarily in contractility and which are in invloved in excitability?Myofibrils are bundles of very fine fibers that extendlengthwise along skeletal muscle fibers and almostfill their sarcoplasm. Sarcomere is a segment of themyofibril between 2 successive Z lines. Transversetubules (T tubules) extend transversely across thesarcoplasm, at a right angle to the long axis of thecell. The SR is a system of membranous tubules in amuscle fiber. The impulse, a temporary electricalimbalance, is conducted over the muscle fiber’ssarcolemma and inward along the T tubules.
  • Explain how the structure of the myofilaments is related to their function. Lying side by side in each myofibril are thousands of thick and thin myofilaments. Myofilament is the term for the chains of (primarily) actin and myosin that pack a muscle fiber. Myosin is responsible forforce generation. It is composed of a globular head with both ATP and actin binding sites, and a long tail involved in its polymerization into myosin filaments. Actin is the other major component in forceproduction. Actin, when polymerized into filaments, forms the "ladder"along which the myosin filaments "climb" to generate motion. Troponin is the major regulator of force production. Its three subunits lie in the groove of each actin filament blocking the myosin binding site, in the absence of ionic calcium. Titin is an enormous (2500 kD) peptide that appears to be involve in maintaining the neatly ordered striation pattern. Closely associated with the myosin molecule, it appears to anchor the myosin network to the actin network. Nebulin is anotheractin associated molecule; Nebulin appears to act as a molecular ruler regulating the length of actin filaments.
  • Explain how the sliding filament theory allows for the shortening of a muscle fiber.The sliding filament theory states that muscle fibers get shorter when the actin filaments slide in on the myosin filaments which pull the z-lines closer together at the same time. When the actin filaments slide inward toward the myosin filaments, the H- zone and I- Band decrease. In a cross bridge each flexion creates a small movement in the actinfilament. In order for a good amount of movement to occur many cross bridges throughout the muscle have to flex repeatedly and quickly.
  • Compare and contrast the role of Ca++ in excitation, contraction, and relaxation of a muscle cell. The latent of excitation period is when Ca++ isreleased, which activates the contractile machinery, and this stretches the series elasticity. During the contraction period, once the tension matches the load, the contraction causes a shortening of theentire muscle. When the relaxation phase occurs the CA++ subsides it is pumped back into the sarcoplasmic reticulum. CA++ leaves the troponin sothat actin and myosin cannot interact. The filaments then slide passively back to their originality. In all three stages CA++ is being used by either being released or coming back in.
  • People who exercise seriously are sometimes told to work amuscle until they "feel the burn". In terms of how muscle is able to release energy, explain what is going on in the muscle early in the exercise and when the muscle is "burning?” During a workout your muscles begin tofeel tired. As you keep going your muscles will feel as if they are burning. There are two steps that create this. When yourbody begins to produce lactic you will feel the burn. This is a source for fuel in themuscles. When the muscles begin fatigued this is because calcium is running out to keep the muscles contracting.
  • Describe the anatomical arrangementof a motor unit. Contrast fine and gross motor units.A single motor unit and the muscle fibersconnected to it act as a unit. This called amotor unit. The number of muscle fibers in each motor unit is different in various parts of the body. Fine motor units are involved in finely graded and skilledmotions such as moving a finger or a toe. These units contain a small number ofmuscle cells. Movements with gross units are involved in bigger contractions and have many muscle cells
  • Using fiber types, design a muscle for a marathon runner. and a different muscle for a 100-yard- dash Sprinter. A marathon runner should have a slick twitch muscle so their muscles can receive more oxygen even though theywill react slower. A sprinter should have a fast twitch muscle so their muscle can react fast and move fast.
  • Explain the meaning of a "unit of combined cells" as it relates to cardiac Muscle. How does the structure arrangement affect its function?A unit of combined cells is . Each unit cell is defined in terms of lattice points which the points in space about which the particles are free to vibrate in a crystal.
  • Describe Rigor Mortis.Rigor mortis refers to the state of a bodyafter death, in which the muscles becomestiff. It commences after around 3 hours, reaching maximum stiffness after 12 hours, and gradually dissipates untilapproximately 72 hours after death. Rigor mortis occurs due to changes in the physiology of muscles when aerobic respiration ceases.
  • Describe in detail the 4 factors that influence the strength of muscle contractions.1. The number of muscle fibers stimulated 2. The relative size of the fibers 3. Frequency of stimulation 4. The degree of muscle strength
  • What are the phases of a twitch contraction? What molecular events occur during each of these phases?Latent: The muscle begins to contract(shorten) there are is no activity butthere is some electrical and chemicalchanges taking place.Contraction: The muscle fibers shortenand this is when trace activity takesplace.Relaxation: The trace activity is goingdownward and the muscle is going backinto its original state and lengthening.
  • How does the treppe effect relate to the warm-up exercises of athletes? The treppe effect takes place when the muscles contract at a more rapid pace and it has. this relates to warming up because if athletes warm up there is noway the treppe effect can take place and their work our will be easier on them.