A motor unit consists of
A) one neuron and all the skeletal muscle fibers it controls.
B) one skeletal muscle fiber and all the neurons that control that fiber.
C) one skeletal muscle fiber and the neuron that controls that fiber.
D) one axon terminal branch and the myofibrils it controls.
Answer: : A
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Human Physiology
- Relative to skeletal muscle, smooth muscle
- An important difference between single-unit and multiunit smooth muscle is the
- Put these myofibers in the order they would be recruited as the body moves from a weak to a strong stimulus:
- The force generated by a single muscle fiber can be increased by
- Skeletal muscle fibers with the greatest endurance rely on ________ for energy.
- The factor(s) that determine the duration of a twitch in various types of fibers is the speed of the
- After death, when metabolism stops, in which step of the contractile cycle must skeletal muscles remain?
- Put these events in the correct chronological sequence:
- Which of the following is NOT a correct comparison of cardiac myocytes to other muscle cell types?
- A change in smooth muscle cell tension in the absence of a change in electrical potential of the cells is described as a
- The calcium release channel in the smooth muscle sarcoplasmic reticulum that is opened by increases in phospholipase C activity is the
- This protein is activated by the Ca2+-calmodulin complex to phosphorylate the myosin light chain protein.
- Which of the following is NOT a property of single-unit smooth muscles?
- Smooth muscle cells lack which protein(s)?
- Compared to skeletal muscle, contraction of smooth muscle cells is
- In order for the bicep muscle to shorten, the force applied by the muscle must be ________ the load applied at the hand.
- In the lever system that characterizes the interaction between bones and muscle, the bones act as the ________ whereas the joints form the ________.
- Before the entire muscle can change length, the force generated by the muscle must stretch the
- A contraction that generates enough force to move a load is known as ________, whereas one that generates force that equals the load is known as ________.
- The nervous system avoids muscle fatigue during submaximal contraction by
- Which fibers fatigue sooner?
- Which fibers generate more force?
- Which of the following statements is NOT correct regarding the motor units and their activation?
- Motor units that control skeletal muscles involved with fine motor movements (eye muscles or the hands) have ________ muscle fibers than motor units that control more gross movements (gastrocnemius muscle of the lower leg).