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Muscle practice questions
Terms in this set (44)
Which of the following muscle types is/are both voluntary and striated?
skeletal muscle only
Muscle cells initiate nerve impulses.
Which of the following is present in muscle cells but absent in most other cell types?
Muscle cells have myoglobin; most other cells do not
The final "go" signal for skeletal muscle contraction is __________.
an increase in intracellular calcium ion levels
The __________ are inward invaginations of the sarcolemma that run deep into the cell and ensure that every myofibril in the muscle fiber contracts at virtually the same time.
The thin myofilaments of skeletal muscle are composed chiefly of __________.
breaks down acetylcholine
Myofibrils are composed of repeating contractile elements called ____
Which of the following statements is FALSE?
During contraction, thin filaments slide past thick filaments so that actin and myosin filaments do not overlap.
When an action potential arrives at the neuromuscular junction, the most immediate result is __________.
the release of acetylcholine from the motor neuron
The first step toward generating a skeletal muscle fiber contraction is nervous stimulation of the muscle fiber. When an action potential arrives at the neuromuscular junction, acetylcholine (ACh) is released. ACh then binds to receptors on the sarcolemma of the muscle fiber. This binding event leads to depolarization of the sarcolemma. As depolarization occurs, a muscle action potential is propagated along the sarcolemma and down the T tubules. The sarcoplasmic reticulum then releases Ca2+ ions into the intracellular environment, and the Ca2+ ions bind to troponin in order to facilitate the formation of actin-myosin cross bridges.
If a muscle is applied to a load that exceeds the muscle's maximum tension, __________.
the muscle length will not change during contraction
Isometric contraction does not lead to load movement. In contrast, isotonic contractions will result in load movement. In isometric contractions, tension may build to the muscle's peak tension-producing capacity, but the muscle does not lengthen or shorten. In isotonic contractions, the muscle will shorten.
Properly controlled skeletal muscle contractions produced by changing the frequency of stimulation and the strength of stimulation are referred to as __________.
graded muscle responses
The most efficient means of producing ATP for muscle contraction is __________.
Under aerobic conditions, muscle cells can carry out aerobic respiration, which is the most efficient metabolic pathway for ATP production. Under anaerobic conditions (oxygen deficient conditions), most of the pyruvic acid produced in glycolysis will be converted to lactic acid to ensure that the muscle cell maintains a supply of ATP. While lactic acid can subsequently be used by some cells to make ATP, the process is not efficient; ATP yields per glucose molecule are extremely low in anaerobic glycolysis.
What would occur if a contracting muscle became totally depleted of ATP?
The muscle would remain in a contracted state because of an inability to break actin-myosin cross bridges.
slow oxidative muscle fiber
fast oxidative muscle fiber
moderately fatigue resistant
fast glycolytic muscle fiber
Slow oxidative muscle fibers are best suited for endurance activities. Fast oxidative fibers are best suited for sprinting. Fast glycolytic fibers are best suited for short-term powerful or intense movements.
Which of the following is FALSE regarding smooth muscle?
Once damaged, smooth muscle is unable to regenerate
Smooth muscle is not striated in appearance, because it lacks sarcomeres. Additionally, smooth muscle tends to be organized in sheets. These sheets are present in all but the smallest blood vessels and in the walls of hollow organs of the respiratory, digestive, reproductive, and urinary systems. The alternating contraction and relaxation of these layers is regulated by the autonomic nervous system. Thus, smooth muscle contraction is under involuntary control. Unlike cardiac and skeletal muscle, smooth muscle is regenerative.
steps in excitation-contraction coupling in skeletal muscle.
Action potential is propagated along the sarcolemma and down the T tubules.
The SR is stimulated to release calcium ions.
Calcium binds to troponin and removes the blocking action of tropomyosin.
Cross bridge formation occurs, and the contraction mechanism is initiated.
steps in cross bridge cycle of skeletal muscle
cross bridge formation
the power stroke or working stroke
cross bridge detachment
cocking of myosin head
An entire skeletal muscle is surrounded by __________.
A motor neuron along with all the muscle fibers it supplies is called a(n) __________.
Which of the following does NOT occur during skeletal muscle contraction?
Calcium binds to myosin heads.
What is the ion released from the terminal cisternae that combines with troponin and removes the blocking action of tropomyosin, resulting in the formation of cross bridges?
Ca2+ combines with troponin, causing troponin to change shape which removes the blocking action of tropomyosin, allowing cross bridges to form.
Each skeletal muscle fiber is controlled by a neuron at a single __________.
Which of the following best describes the composition of the structure known as a triad in a skeletal muscle fiber?
terminal cisterna, transverse tubule, and terminal cisterna
n the sliding filament model of muscle contraction, the myofilaments slide over each other, resulting in the overlapping of actin and __________.
Myoglobin is a red pigment that provides oxygen for cellular respiration in skeletal muscle fibers.
The functional unit of contraction in a skeletal muscle fiber is the __________.
The space between the axon terminus of the neuron and the sarcolemma of the muscle fiber is the __________.
Continued mild or partial contraction of a muscle that keeps it healthy and ready to respond is known as muscle __________.
The type of muscle contraction in which the muscle fibers produce increased tension although the muscle neither shortens nor lengthens is called __________.
Which of the following statements about smooth muscle is true?
Fibers are small and spindle-shaped.
Smooth muscle fibers are small and spindle-shaped. Cardiac muscle has branching fibers and is striated and involuntary. Skeletal muscle has peripherally located nuclei and has rapid and forceful contractions.
Which of the following substances increases in quantity during repetitive muscle contraction during oxygen deficit?
The sequence of electrical changes that occurs along the sarcolemma when a muscle fiber is stimulated is known as the __________.
Which of the following allows recoil of the muscle fiber when contraction ends?
Which one of the following binds calcium ions in a smooth muscle, causing contraction?
During the phase of excitation-contraction coupling of skeletal muscle, what occurs immediately after the action potential spreads down the T tubule?
The sarcoplasmic reticulum releases calcium.
Transmission of the action potential along the T tubules of the triads causes the voltage-sensitive tubule proteins of the sarcoplasmic reticulum to change shape, releasing calcium into the cytosol.
Which type of skeletal muscle contains abundant quantities of glycogen?
fast glycolytic fibers
Myofilament cross bridges form when which two structures bond?
myosin heads and globular actin
The refractory period in which the muscle will NOT contract if stimulated occurs during __________ of the muscle cell.
Where does 95% of the energy needed for contraction come from during moderate exercise?
the alternating contraction and relaxation of opposing layers of smooth muscle is referred to as __________.
THIS SET IS OFTEN IN FOLDERS WITH...
Ch 9 A & P 9.03
Module 3: Section 9.04
anatomy chapter 7 & 8
muscles and muscle tissues
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