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T3 L2: Physiology of Skeletal Muscle Contraction (HJW)
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T3 L2: Physiology of Skeletal Muscle Contraction (HJW)

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Questions and Answers

Which of the following is NOT a component of a sarcomere?

  • A bands
  • I bands
  • M lines (correct)
  • Z lines

    • What is the role of troponin in muscle contraction?

  • Troponin binds to actin
  • Troponin binds to tropomyosin
  • Troponin binds to myosin
  • Troponin binds to calcium ions (correct)

    • Which of the following is a marker for total muscle breakdown?

  • Cardiac TnI
  • Total TnI (correct)
  • Troponin C
  • Troponin I

    • Which ion is involved in the excitation-contraction coupling in muscle cells?

    <p>Calcium</p> Signup and view all the answers

    Which of the following is NOT a type of muscle fiber?

    <p>Type III</p> Signup and view all the answers

    What is the process called when myosin breaks down ATP during muscle contraction?

    <p>Crossbridge cycle</p> Signup and view all the answers

    Which type of muscle fiber has a higher myoglobin content and many mitochondria?

    <p>Slow twitch (Type I)</p> Signup and view all the answers

    Which type of muscle fiber has a lower myoglobin content and relies more on glycolysis for energy production?

    <p>Fast twitch (Type II)</p> Signup and view all the answers

    Which type of muscle fiber has a slower contraction rate and higher fatigue resistance?

    <p>Slow twitch (Type I)</p> Signup and view all the answers

    Which type of muscle fiber has a larger diameter and fewer mitochondria?

    <p>Fast twitch (Type II)</p> Signup and view all the answers

    Which type of muscle fiber is primarily used in activities requiring endurance, such as long-distance running?

    <p>Slow twitch (Type I)</p> Signup and view all the answers

    Which type of muscle fiber is primarily used in activities requiring short bursts of power, such as sprinting?

    <p>Fast twitch (Type II)</p> Signup and view all the answers

    What is the main difference between isometric and isotonic muscle contractions?

    <p>Isometric contractions generate a variable force while the length of the muscle remains unchanged, while isotonic contractions generate a constant force while the length of the muscle changes</p> Signup and view all the answers

    Which type of muscle fibers are responsible for fine gradation of force for small movements?

    <p>Slow red fibers</p> Signup and view all the answers

    What is the function of the patellar reflex?

    <p>Posture and balance</p> Signup and view all the answers

    Which type of muscle fibers detect stretch and length of the central non-contracting region using stretch receptors?

    <p>Type 1a fibers</p> Signup and view all the answers

    What happens when there is absence of the patellar reflex?

    <p>All of the above</p> Signup and view all the answers

    Which reflex protects the muscle from overloading and can lead to muscle force decrease?

    <p>Tendon reflex</p> Signup and view all the answers

    What is the function of the Golgi Tendon Organ?

    <p>Decreasing muscle force</p> Signup and view all the answers

    What happens in upper motor neuron disease?

    <p>Spasticity and hypertonia</p> Signup and view all the answers

    What is the role of lower motor neurons?

    <p>Drive contraction of edge of intrafusal fibers</p> Signup and view all the answers

    What is the relationship between neural drive and force generation?

    <p>Directly proportional</p> Signup and view all the answers

    Which of the following is true about the mechanism of muscle contraction at the molecular level?

    <p>Myosin heads are blocked from binding to actin by tropomyosin.</p> Signup and view all the answers

    Which of the following is true about force generation in muscle fibers?

    <p>Force generation is dependent on the binding of myosin heads to thin filaments.</p> Signup and view all the answers

    Which of the following is true about the cross-bridge cycle in muscle contraction?

    <p>Myosin releases ADP and Pi during the power stroke.</p> Signup and view all the answers

    Which of the following is true about rigor mortis?

    <p>Rigor mortis occurs due to the depletion of ATP in muscle cells.</p> Signup and view all the answers

    Which of the following is true about creatine and creatinine?

    <p>Creatine phosphokinase is an enzyme that adds phosphate to creatinine.</p> Signup and view all the answers

    Which of the following is true about calcium in muscle contraction?

    <p>Calcium triggers depolarization in muscle fibers.</p> Signup and view all the answers

    Which of the following is true about tetany in muscle contraction?

    <p>Tetany occurs when there is insufficient resequestration of calcium.</p> Signup and view all the answers

    Which molecule determines whether actin-myosin interaction can occur in skeletal muscle?

    <p>Troponin I</p> Signup and view all the answers

    What is the role of tropomyosin in muscle contraction?

    <p>It blocks the binding of myosin heads to actin</p> Signup and view all the answers

    What is the function of troponin C in skeletal muscle?

    <p>It binds to calcium ions</p> Signup and view all the answers

    What is the mechanism of muscle contraction at the molecular level?

    <p>Actin and myosin filaments slide past each other</p> Signup and view all the answers

    Which type of muscle contraction is voluntary?

    <p>Isotonic contraction</p> Signup and view all the answers

    What is the main difference between skeletal muscle and cardiac muscle?

    <p>Skeletal muscle is striated, while cardiac muscle is smooth</p> Signup and view all the answers

    What is the function of motor units in muscle contraction?

    <p>To generate force by contracting muscle fibers</p> Signup and view all the answers

    What is the role of calcium in muscle contraction?

    <p>To initiate the sliding filament mechanism</p> Signup and view all the answers

    Which molecule is responsible for holding high energy phosphate bonds in muscle fibers?

    <p>Creatine phosphate</p> Signup and view all the answers

    What happens to muscle force when the actin filaments start getting in the way of each other?

    <p>It decreases</p> Signup and view all the answers

    What is the role of ATP in muscle contraction?

    <p>It allows myosin to release from actin</p> Signup and view all the answers

    What is the condition called when the cross bridge cycle gets stuck in the state where myosin has grabbed onto actin and can no longer release it?

    <p>Rigor mortis</p> Signup and view all the answers

    Which type of muscle fiber has a higher myoglobin content and many mitochondria?

    <p>Slow twitch fibers</p> Signup and view all the answers

    What is the main difference between slow twitch and fast twitch muscle fibers?

    <p>Slow twitch fibers are used for slow and sustained force generation, while fast twitch fibers are used for fast and intermittent movements</p> Signup and view all the answers

    Which type of muscle fiber is primarily used in activities requiring short bursts of power, such as sprinting?

    <p>Fast twitch fibers</p> Signup and view all the answers

    What is the relationship between muscle fibers and motor units?

    <p>Motor units are made up of muscle fibers</p> Signup and view all the answers

    What is the role of the L type calcium channels in muscle contraction?

    <p>They allow calcium to come in when they depolarize</p> Signup and view all the answers

    What happens when the calcium release channels open in muscle cells?

    <p>They release calcium from the sarcoplasmic reticulum</p> Signup and view all the answers

    What is the role of the sarcoplasmic reticulum in muscle contraction?

    <p>It pumps calcium back into the sarcoplasmic reticulum</p> Signup and view all the answers

    What is the relationship between calcium concentration in the sarcoplasmic reticulum and the cytosol?

    <p>High calcium in the sarcoplasmic reticulum, low calcium in the cytosol</p> Signup and view all the answers

    Which of the following is true about creatine and creatinine?

    <p>Creatinine is a breakdown product of creatine and is used as a marker of kidney function</p> Signup and view all the answers

    What is the role of troponin in muscle contraction?

    <p>Troponin binds to calcium and moves tropomyosin to expose the myosin binding sites on actin</p> Signup and view all the answers

    What is the main difference between isometric and isotonic muscle contractions?

    <p>Isometric contractions generate force without movement, while isotonic contractions generate force with movement</p> Signup and view all the answers

    Which of the following is true about force generation in muscle fibers?

    <p>Force generation in muscle fibers is dependent on the length-tension relationship</p> Signup and view all the answers

    Which type of muscle fiber is primarily used for activities requiring endurance, such as long-distance running?

    <p>Type I</p> Signup and view all the answers

    Which type of muscle fiber has a slower contraction rate and higher fatigue resistance?

    <p>Type I</p> Signup and view all the answers

    Which type of muscle fiber has a higher myoglobin content and many mitochondria?

    <p>Type I</p> Signup and view all the answers

    What is the role of the Golgi Tendon Organ?

    <p>Protect the muscle from overloading</p> Signup and view all the answers

    What is the function of the patellar reflex?

    <p>Detect stretch and length of the central non-contracting region</p> Signup and view all the answers

    What is the main difference between isometric and isotonic muscle contractions?

    <p>The force generated in isotonic contractions is constant, while in isometric contractions, the length of the muscle changes</p> Signup and view all the answers

    Which of the following is the correct order of muscle structures from largest to smallest?

    <p>Fascicle, myofibril, myofilament</p> Signup and view all the answers

    How many thin filaments are adjacent to one thick filament?

    <p>3</p> Signup and view all the answers

    How many thick filaments are adjacent to one thin filament?

    <p>3</p> Signup and view all the answers

    Which bands become shorter during contraction in the sarcomere?

    <p>A and I</p> Signup and view all the answers

    Which of the following proteins reside on thin filaments?

    <p>Actin, tropomyosin, troponin</p> Signup and view all the answers

    What is the basis of the striations in skeletal muscle?

    <p>The distribution of thick and thin filaments</p> Signup and view all the answers

    Which of the following is true about the size principle in muscle activity?

    <p>The size principle determines the order of recruitment of motor units during muscle activity.</p> Signup and view all the answers

    Which of the following is an example of eccentric contraction of muscle?

    <p>Landing at the end of a long jump.</p> Signup and view all the answers

    What is the difference between isotonic and isometric force generation?

    <p>Isotonic force generation implies that the muscle changes size, while isometric force generation implies that the muscle does not change size.</p> Signup and view all the answers

    What is the difference between the stretch reflex and the tendon reflex?

    <p>The stretch reflex decreases muscle force and responds to stretch, while the tendon reflex increases muscle force and responds to tension.</p> Signup and view all the answers

    Which of the following muscles would you expect to have a predominance of slow twitch fibers?

    <p>Gastrocnemius.</p> Signup and view all the answers

    What happens during isometric force generation?

    <p>The muscle generates constant tension while not changing size.</p> Signup and view all the answers

    Which of the following is true about slow twitch muscle fibers?

    <p>They have a higher myoglobin content</p> Signup and view all the answers

    Which of the following is true about fast twitch muscle fibers?

    <p>They have less fatigue resistance</p> Signup and view all the answers

    What is the main difference between a motor unit and a muscle fiber?

    <p>A motor unit determines the fiber type, while a muscle fiber determines the strength or accuracy</p> Signup and view all the answers

    Which of the following is true about slow twitch muscle fibers?

    <p>They have a higher myoglobin content</p> Signup and view all the answers

    Which of the following is true about fast twitch muscle fibers?

    <p>They have less fatigue resistance</p> Signup and view all the answers

    What is the main difference between a motor unit and a muscle fiber?

    <p>A motor unit determines the fiber type, while a muscle fiber determines the strength or accuracy</p> Signup and view all the answers

    Which of the following is true about the molecular mechanism of muscle contraction in skeletal muscle?

    <p>The hydrolysis of ATP by myosin provides the energy for the power stroke</p> Signup and view all the answers

    What is the role of tropomyosin in skeletal muscle contraction?

    <p>Tropomyosin physically occludes the myosin interaction site on the actin filament</p> Signup and view all the answers

    What is the main difference between skeletal muscle troponin and cardiac muscle troponin?

    <p>Skeletal muscle troponin binds 4 Ca2+ ions, while cardiac muscle troponin binds 3 Ca2+ ions</p> Signup and view all the answers

    What is the molecular mechanism for the reduction in force when a sarcomere is stretched beyond optimal?

    <p>The myosin heads of the thick filaments detach from the actin filaments</p> Signup and view all the answers

    What is the molecular mechanism for the increase in force when a sarcomere is contracted beyond optimal?

    <p>The myosin heads of the thick filaments form stronger cross-bridges with the actin filaments</p> Signup and view all the answers

    What happens to the cross-bridge cycle when there is no ATP available?

    <p>The myosin heads of the thick filaments detach from the actin filaments</p> Signup and view all the answers

    Which of the following is true about the role of calcium in muscle contraction?

    <p>Calcium binds to troponin, which allows for the exposure of the myosin-binding sites on actin.</p> Signup and view all the answers

    What is the main difference between skeletal muscle and smooth muscle?

    <p>Skeletal muscle is striated, while smooth muscle is not.</p> Signup and view all the answers

    What is the function of troponin in muscle contraction?

    <p>Troponin binds to tropomyosin, exposing the myosin-binding sites on actin.</p> Signup and view all the answers

    What is the role of the sarcoplasmic reticulum in muscle contraction?

    <p>The sarcoplasmic reticulum stores and releases calcium ions for muscle contraction.</p> Signup and view all the answers

    What is the function of the Golgi Tendon Organ?

    <p>The Golgi Tendon Organ detects changes in muscle tension and controls muscle tension.</p> Signup and view all the answers

    What is the difference between isometric and isotonic muscle contractions?

    <p>In isometric contractions, the muscle length remains constant, while in isotonic contractions, the muscle length changes.</p> Signup and view all the answers

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