Which of the following can trigger a muscle twitch?release of acetylcholine or electrical stimulationrelease of acetylcholine or release of calcium from the sarcolemmarelease of acetylcholineelectrical stimulationrelease of calcium from the sarcolemma
  • The length of the muscle decreases with contraction.
  • release of acetylcholine or electrical stimulation
  • Calcium is released from the sarcoplasmic reticulum.
  • increasing the stimulus frequency
What is the minimum voltage needed to generate active force in the skeletal muscle?
  • threshold voltage
  • active force
  • shortening phase
  • the longest starting length
Why does wave summation occur?
  • Muscle tension is produced, and the weight will not move.
  • Muscle fibers are partially contracted when the next stimulus arrives.
  • The sarcomeres are increasing in length, and the force generated decreases.
  • The number of cross-bridges between actin and myosin varies.
Which of the following is generated when cross-bridges form between actin and myosin?
  • the number of motor units activated
  • The active force can increase or decrease, depending on the starting resting length of the muscle.
  • active force
  • Calcium is released from the sarcoplasmic reticulum.
In the lab, a researcher finds that the threshold stimulus to induce an action potential in a muscle fiber's sarcolemma was 3.0 volts. Which of the following would result in muscle tension?4.0 volts2.0 volts3.0 volts3.0 volts and 4.0 volts1.0 volt
  • 3.0 volts and 4.0 volts
  • both fused and unfused tetanus
  • the longest starting length
  • release of acetylcholine or electrical stimulation
Which of the following describes the relationship between length and tension?
  • The sarcomeres are increasing in length, and the force generated decreases.
  • The active force can increase or decrease, depending on the starting resting length of the muscle.
  • When stimulus frequency increases, muscle tension increases to a maximum value.
  • active force
When acetylcholine binds to its receptors, it results in __________.
  • The length of the muscle decreases with contraction.
  • the end plate potential, a graded depolarization, and a change in ion permeability
  • The number of cross-bridges between actin and myosin varies.
  • The active force can increase or decrease, depending on the starting resting length of the muscle.
The speed of muscle contraction is called the _______.
  • motor unit - motor neuron
  • shortening phase
  • threshold voltage
  • shortening velocity
Which of the following occurs during isotonic concentric contraction?
  • Calcium is released from the sarcoplasmic reticulum.
  • The length of the muscle decreases with contraction.
  • the number of motor units activated
  • The muscle relaxes fully between contractions.
When the frequency of stimulation of a muscle is great enough, _______.
  • increased to a point until it reached a plateau
  • The length of the muscle decreases with contraction.
  • The number of cross-bridges between actin and myosin varies.
  • wave summation results and muscle twitches overlap.
As the stimulus voltage increased, the resulting muscle tension _______.
  • increased to a point until it reached a plateau
  • The muscle force generated increased.
  • wave summation results and muscle twitches overlap.
  • increasing the voltage applied
When wave summation occurs, _______.
  • The muscle force generated increased.
  • The muscle relaxes fully between contractions.
  • the muscle force generated increase
  • Muscle fibers are partially contracted when the next stimulus arrives.
The resting length of the muscle _______.
  • occurs when the muscle is relaxed
  • receptors in the motor end plate
  • increasing the voltage applied
  • both fused and unfused tetanus
Why does the active force of skeletal muscle change with the muscle's resting length?
  • Muscle tension is produced, and the weight will not move.
  • The number of cross-bridges between actin and myosin varies.
  • The length of the muscle decreases with contraction.
  • the number of motor units activated
A motor unit is defined as ______
  • Muscle fibers are partially contracted when the next stimulus arrives.
  • the end plate potential, a graded depolarization, and a change in ion permeability
  • the axon terminals of a single motor neuron and all of the muscle fibers that it stimulates
  • The sarcomeres are increasing in length, and the force generated decreases.
Which starting length of the muscle provided the maximum total force?
  • increasing the voltage applied
  • the longest starting length
  • motor unit - motor neuron
  • The length of the muscle decreases with contraction.
Where does the acetylcholine that stimulates muscle contraction bind?
  • Cross-bridge cycling is taking place.
  • receptors in the motor end plate
  • occurs when the muscle is relaxed
  • increasing the voltage applied
Muscle twitches overlap with _______.
  • motor unit - motor neuron
  • both fused and unfused tetanus
  • occurs when the muscle is relaxed
  • The muscle relaxes fully between contractions.
The graph of the length-tension relationship illustrates _______.
  • the optimal sarcomere length for muscle contraction and the amount of overlap between the thick and thin filaments in the resting muscle
  • The sarcomeres are increasing in length, and the force generated decreases.
  • When stimulus frequency increases, muscle tension increases to a maximum value.
  • The active force can increase or decrease, depending on the starting resting length of the muscle.
Which of the following is true of the maximum stimulus frequency?Muscle has reached maximal tetanic tension.Muscle force will decrease.No greater muscle force can be generated and the muscle has reached maximal tetanic tension.No greater muscle force can be generated and muscle force will decrease.No greater muscle force can be generated.
  • When stimulus frequency increases, muscle tension increases to a maximum value.
  • release of acetylcholine or electrical stimulation
  • No greater muscle force can be generated and the muscle has reached maximal tetanic tension.
  • The active force can increase or decrease, depending on the starting resting length of the muscle.
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