Flex Your Muscle Knowledge
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Questions and Answers

Which property of muscle allows it to respond to a stimulus?

  • Contractility
  • Extensibility
  • Elasticity
  • Excitability (correct)

    • Which type of muscle tissue is responsible for locomotion and facial expressions?

  • Smooth
  • Cardiac
  • Skeletal (correct)
  • None of the above

    • Which system controls the contraction of cardiac muscle?

  • Muscular system
  • Endocrine system
  • Skeletal system
  • Autonomic nervous system (correct)

    • Which protein aligns the thick and thin filaments properly in skeletal muscle tissue?

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

    What is the function of myosin in skeletal muscle tissue?

    <p>Generates force during contraction</p> Signup and view all the answers

    What happens when calcium ions bind to troponin in relaxed muscle?

    <p>Tropomyosin moves away from myosin-binding sites</p> Signup and view all the answers

    What is the role of titin in skeletal muscle tissue?

    <p>Stabilizes the position of myosin</p> Signup and view all the answers

    Which ion has a higher concentration inside the cell compared to outside the cell?

    <p>K+</p> Signup and view all the answers

    What is the resting membrane potential of a cell?

    <p>-70 mV</p> Signup and view all the answers

    What type of ion channels open and close in response to small voltage changes across the plasma membrane?

    <p>Voltage-gated</p> Signup and view all the answers

    What is the phase of an action potential where the inside of the plasma membrane becomes less negative?

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

    According to the text, what is the response of a muscle fiber to a sub-threshold stimulus?

    <p>No action potential; no contraction</p> Signup and view all the answers

    According to the text, what is the strength of contraction dependent on?

    <p>Size of the motor unit and number of units recruited</p> Signup and view all the answers

    According to the text, what happens to the strength of contraction as the number of motor units responding to a stimulus increases?

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

    According to the text, what is the term used to describe the phenomenon where each subsequent contraction is stronger than the previous one until they all become equal?

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

    According to the text, what happens to muscle tension as the frequency of action potentials increases?

    <p>Muscle tension increases</p> Signup and view all the answers

    According to the text, what is the term used to describe the phenomenon where there is no relaxation between muscle contractions?

    <p>Complete tetanus</p> Signup and view all the answers

    Which connective tissue surrounds a whole muscle and many fascicles?

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

    Which connective tissue surrounds a group of muscle fibers?

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

    What is the function of Transverse (T) tubules in a muscle cell?

    <p>Ensure that action potential excites all parts of the muscle fiber at the same time</p> Signup and view all the answers

    What is the basic functional unit of a myofibril?

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

    Which of the following is true about the neuromuscular junction?

    <p>The neuromuscular junction is where communication occurs between a motor neuron and a muscle fiber</p> Signup and view all the answers

    What is the role of acetylcholine in the neuromuscular junction?

    <p>Acetylcholine is a neurotransmitter released from the presynaptic membrane that stimulates the production of an action potential in the postsynaptic membrane</p> Signup and view all the answers

    What happens when acetylcholine binds to ligand-gated Na+ channels on the postsynaptic membrane?

    <p>Ligand-gated Na+ channels open and Na+ enters the postsynaptic cell, causing the postsynaptic membrane to depolarize</p> Signup and view all the answers

    What is the role of acetylcholinesterase in the neuromuscular junction?

    <p>Acetylcholinesterase is an enzyme that removes acetylcholine from the synaptic cleft, preventing its accumulation</p> Signup and view all the answers

    Which of the following is true during the depolarization phase of the action potential?

    <p>The membrane potential becomes more positive</p> Signup and view all the answers

    What is the role of sodium (Na+) channels during the depolarization phase of the action potential?

    <p>They open and allow sodium ions to diffuse into the cell</p> Signup and view all the answers

    What causes the repolarization phase of the action potential?

    <p>The opening of potassium (K+) channels</p> Signup and view all the answers

    Which of the following is NOT a function of the muscular system?

    <p>Constriction of organs and vessels</p> Signup and view all the answers

    Which property of muscle allows it to respond to a stimulus?

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

    Which type of muscle tissue is controlled involuntarily by the endocrine and autonomic nervous systems?

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

    Which connective tissue surrounds a whole muscle and many fascicles?

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

    Which ion has a higher concentration inside the cell compared to outside the cell?

    <p>K+</p> Signup and view all the answers

    What is the resting membrane potential of a cell?

    <p>-85 mV</p> Signup and view all the answers

    What is the role of the sodium-potassium pump?

    <p>To pump sodium ions out of the cell in exchange for potassium ions</p> Signup and view all the answers

    What is the function of Transverse (T) tubules in a muscle cell?

    <p>To transmit action potentials deep into the muscle cell</p> Signup and view all the answers

    Which protein stabilizes the position of myosin and accounts for much of the elasticity and extensibility of myofibrils?

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

    What is the region in the A band where actin and myosin do not overlap called?

    <p>H zone</p> Signup and view all the answers

    What is the role of tropomyosin in muscle contraction?

    <p>Moves tropomyosin away from myosin-binding sites</p> Signup and view all the answers

    What is the function of the M line in skeletal muscle tissue?

    <p>Forms the M-line and binds Titan</p> Signup and view all the answers

    Which connective tissue surrounds a group of muscle fibers?

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

    What is the function of Transverse (T) tubules in a muscle cell?

    <p>To ensure that action potential excites all parts of the muscle fiber at the same time</p> Signup and view all the answers

    What is the role of acetylcholine in the neuromuscular junction?

    <p>To stimulate muscle fibers to contract</p> Signup and view all the answers

    What is the basic functional unit of a myofibril?

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

    Which structure releases the neurotransmitter acetylcholine into the synaptic cleft?

    <p>Synaptic vesicles</p> Signup and view all the answers

    What is the role of acetylcholinesterase in the neuromuscular junction?

    <p>To remove acetylcholine from the synaptic cleft</p> Signup and view all the answers

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

    <p>To reabsorb calcium ions from the cytoplasm</p> Signup and view all the answers

    What is the role of troponin in muscle contraction?

    <p>To bind to calcium ions and initiate muscle contraction</p> Signup and view all the answers

    What is the term used to describe the phenomenon where the strength of contraction increases as the number of motor units responding to a stimulus increases?

    <p>Multiple-wave summation</p> Signup and view all the answers

    What is the term used to describe the phenomenon where each subsequent contraction is stronger than the previous one until they all become equal?

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

    What is the term used to describe the phenomenon where there is no relaxation between muscle contractions?

    <p>Complete tetanus</p> Signup and view all the answers

    What is the term used to describe the phenomenon where the strength of contraction depends upon recruitment of motor units?

    <p>Multiple motor unit summation</p> Signup and view all the answers

    What is the term used to describe the phenomenon where muscle fibers partially relax between contractions during high frequency stimulation?

    <p>Incomplete tetanus</p> Signup and view all the answers

    What is the term used to describe the phenomenon where muscle fibers do not relax between contractions during high frequency stimulation?

    <p>Complete tetanus</p> Signup and view all the answers

    During the depolarization phase of the action potential, the membrane potential changes from approximately -85 mV to approximately +20 mV. During the repolarization phase, the inside of the plasma membrane changes from approximately +20 mV back to -85 mV.

    <p>a) -85 mV to +20 mV</p> Signup and view all the answers

    What is the change in membrane potential during the repolarization phase of the action potential?

    <p>a) +20 mV to -85 mV</p> Signup and view all the answers

    What is the difference in membrane potential between the depolarization and repolarization phases of the action potential?

    <p>b) 105 mV</p> Signup and view all the answers

    What is the total change in membrane potential during the action potential?

    <p>c) -20 mV to +85 mV</p> Signup and view all the answers

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