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Muscular Physiology

Ashley
Ashley

Skeletal muscles provide movement through contractions, generate heat through catabolism, and maintain posture through partial contractions. Muscles are excitable through nerve signals and use structures like myofibrils, sarcomeres, and troponin to generate force through the sliding filament theory when calcium ions bind during excitation and relax when calcium ions unbind. Different fiber types allow for specialized functions in sprinters versus marathon runners.

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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 of the body as a whole (locomotion) or it its parts. Heat production: Muscle cells produce heat by the process known as catabolism. Skeletal muscle contractions constitute one of the most important parts of the mechanism for maintaining homeostasis of temperature. Posture: The continued partial contraction of many skeletal muscles makes possible standing, sitting and maintaining a relatively stable position of the body while walking, running or performing other movements. Contrability: is the ability to contract or shorten that allows muscle tissue to pull on bones and produce body movement. Extensibility is the ability to extend or stretch that allows muscles to 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 stimulated and its 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 muscle fibers? Which of the structures involved primarily in contractility and which are in invloved in excitability? Myofibrils are bundles of very fine fibers that extend lengthwise along skeletal muscle fibers and almost fill their sarcoplasm. Sarcomere is a segment of the myofibril between 2 successive Z lines. Transverse tubules (T tubules) extend transversely across the sarcoplasm, at a right angle to the long axis of the cell. The SR is a system of membranous tubules in a muscle fiber. The impulse, a temporary electrical imbalance, is conducted over the muscle fibers sarcolemma 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 for force 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 force production. 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 another actin 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 actin filament. 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++ is released, 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 the entire muscle. When the relaxation phase occurs the CA++ subsides it is pumped back into the sarcoplasmic reticulum. CA++ leaves the troponin so that 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 a muscle 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 to feel tired. As you keep going your muscles will feel as if they are burning. There are two steps that create this. When your body begins to produce lactic you will feel the burn. This is a source for fuel in the muscles. When the muscles begin fatigued this is because calcium is running out to keep the muscles contracting.
Describe the anatomical arrangement of a motor unit. Contrast fine and gross motor units. A single motor unit and the muscle fibers connected to it act as a unit. This called a motor 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 skilled motions such as moving a finger or a toe. These units contain a small number of muscle 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 they will 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 body after death, in which the muscles become stiff. It commences after around 3 hours, reaching maximum stiffness after 12 hours, and gradually dissipates until approximately 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 but there is some electrical and chemical changes taking place. Contraction: The muscle fibers shorten and this is when trace activity takes place. Relaxation: The trace activity is going downward and the muscle is going back into 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 no way the treppe effect can take place and their work our will be easier on them.

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Muscular Physiology

  • 2. Explain how skeletal muscles provide movement, heat, and posture. Are all of these functions unique to muscles? Movement: Skeletal muscle contractions produce movements of the body as a whole (locomotion) or it its parts. Heat production: Muscle cells produce heat by the process known as catabolism. Skeletal muscle contractions constitute one of the most important parts of the mechanism for maintaining homeostasis of temperature. Posture: The continued partial contraction of many skeletal muscles makes possible standing, sitting and maintaining a relatively stable position of the body while walking, running or performing other movements. Contrability: is the ability to contract or shorten that allows muscle tissue to pull on bones and produce body movement. Extensibility is the ability to extend or stretch that allows muscles to return to their resting length after having contracted.
  • 3. 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 stimulated and its also known as irritability. Because skeletal muscle cells are excitable, they can respond to regulate mechanisms such as nerve signals.
  • 4. What structures are unique to skeletal muscle fibers? Which of the structures involved primarily in contractility and which are in invloved in excitability? Myofibrils are bundles of very fine fibers that extend lengthwise along skeletal muscle fibers and almost fill their sarcoplasm. Sarcomere is a segment of the myofibril between 2 successive Z lines. Transverse tubules (T tubules) extend transversely across the sarcoplasm, at a right angle to the long axis of the cell. The SR is a system of membranous tubules in a muscle fiber. The impulse, a temporary electrical imbalance, is conducted over the muscle fibers sarcolemma and inward along the T tubules.
  • 5. 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 for force 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 force production. 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 another actin associated molecule; Nebulin appears to act as a molecular ruler regulating the length of actin filaments.
  • 6. 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 actin filament. In order for a good amount of movement to occur many cross bridges throughout the muscle have to flex repeatedly and quickly.
  • 7. Compare and contrast the role of Ca++ in excitation, contraction, and relaxation of a muscle cell. The latent of excitation period is when Ca++ is released, 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 the entire muscle. When the relaxation phase occurs the CA++ subsides it is pumped back into the sarcoplasmic reticulum. CA++ leaves the troponin so that 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.
  • 8. People who exercise seriously are sometimes told to work a muscle 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 to feel tired. As you keep going your muscles will feel as if they are burning. There are two steps that create this. When your body begins to produce lactic you will feel the burn. This is a source for fuel in the muscles. When the muscles begin fatigued this is because calcium is running out to keep the muscles contracting.
  • 9. Describe the anatomical arrangement of a motor unit. Contrast fine and gross motor units. A single motor unit and the muscle fibers connected to it act as a unit. This called a motor 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 skilled motions such as moving a finger or a toe. These units contain a small number of muscle cells. Movements with gross units are involved in bigger contractions and have many muscle cells
  • 10. 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 they will react slower. A sprinter should have a fast twitch muscle so their muscle can react fast and move fast.
  • 11. 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.
  • 12. Describe Rigor Mortis. Rigor mortis refers to the state of a body after death, in which the muscles become stiff. It commences after around 3 hours, reaching maximum stiffness after 12 hours, and gradually dissipates until approximately 72 hours after death. Rigor mortis occurs due to changes in the physiology of muscles when aerobic respiration ceases.
  • 13. 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
  • 14. 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 but there is some electrical and chemical changes taking place. Contraction: The muscle fibers shorten and this is when trace activity takes place. Relaxation: The trace activity is going downward and the muscle is going back into its original state and lengthening.
  • 15. 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 no way the treppe effect can take place and their work our will be easier on them.