Chapter 9 Muscles and Muscle Tissue Flashcards
- What is the role of calcium ions in the
contraction of skeletal muscle?
A. The release of calcium ions triggers the immediate regeneration of creatine phosphate to power the contraction.
B. Calcium ions bind to the troponin‐tropomyosin complex and remove their inhibitory action on actin/myosin interaction.
C. Calcium ions directly activate ATPase in the myosin head.
D. Calcium ions bind to lactic acid to remove it from the contracting muscle.
B. Calcium ions bind to the troponin‐tropomyosin complex and remove their inhibitory action on actin/myosin interaction.
The functional unit of a skeletal muscle fiber is the \_\_\_\_\_\_\_\_. A. sarcomere B. myofibril C. sarcoplasmic reticulum D. myofilament
A. sarcomere
Interactions between thin and thick
myofilaments of the sarcomere are responsible for ________.
A. the striped appearance of skeletal muscle
B. muscle relaxation
C. the conduction of action potentials in the muscle fiber
D. muscle contraction
D. muscle contraction
During muscle contraction, all of the
following occur EXCEPT ________.
A. calcium binds to troponin
B. myosin heads bind to actin
C. calcium concentrations in the sarcoplasm decrease
D. calcium concentration in the sarcoplasm increase
C. calcium concentrations in the sarcoplasm decrease
During a muscle contraction, muscle fibers
shorten when ________.
A. actin filaments become shorter when they combine with myosin heads
B. myosin heads rotate when they attach to actin, causing the myosin filaments to fold in the middle
C. thin myofilaments are pulled toward the center of the sarcomere by the pivoting of the myosin heads
D. ACh reduces the friction between thin and thick myofilaments,
C. thin myofilaments are pulled toward the center of the sarcomere by the pivoting of the myosin heads
The elaborate network of membranes in skeletal muscle cells that functions in calcium storage is the \_\_\_\_\_\_\_\_\_. A. rough endoplasmic reticulum B. mitochondria C. intermediate filament network D. sarcoplasmic reticulum
D. sarcoplasmic reticulum
What is the function of T tubules?
A. They store calcium.
B. They provide elasticity to the muscle.
C. They hold the thick filaments to the Z line.
D. They conduct action potentials from the sarcolemma to the interior of the muscle cell.
D. They conduct action potentials from the sarcolemma to the interior of the muscle cell.
One tranverse tubule plus two adjacent terminal cisternae form a \_\_\_\_\_\_\_\_\_\_\_. A. sarcomere B. triad C. calcium release channel D. fiber
B. triad
Which ion links excitation to contraction in a skeletal muscle fiber? A. Sodium B. Magnesium C. Calcium D. Potassium
C. Calcium
As action potentials travel down a T tubule, a voltage‐sensitive protein changes shape. This shape change opens a \_\_\_\_\_\_\_\_\_\_\_\_. A. voltage‐gated sodium channel B. voltage‐gated potassium channel C. calcium release channel D. ligand‐gated ion channel
C. calcium release channel
The portion of the sarcolemma in contact with the axon terminals is called the \_\_\_\_\_\_\_\_. A. synaptic cleft B. motor end plate C. neuromuscular junction D. motor unit
B. motor end plate
At the neuromuscular junction, calcium ions act to ________.
A. release the inhibition on Z discs
B. remove the blocking action of tropomyosin
C. cause ATP binding to actin
D. release synaptic vesicles from the axon terminal
D. release synaptic vesicles from the axon terminal
The first thing that occurs when the axon terminal releases ACh is ________.
A. calcium ions return to the terminal cisternae of the SR
B. the troponin blocks the tropomyosin
C. calcium diffuses into the axon terminal of the motor neuron
D. diffusion of ACh across the synaptic cleft
D. diffusion of ACh across the synaptic cleft
What type of ion channel opens in response
to an action potential arriving at the axon terminal?
A. Voltage‐gated sodium
B. Voltage‐gated potassium
C. Ligand‐gated cation
D. Voltage‐gated calcium
D. Voltage‐gated calcium
What is the name of the enzyme that degrades ACh? A. ATPase B. Acetylcholinesterase C. Serine hydroxylase D. N‐methyl transferase
B. Acetylcholinesterase
Of the following muscle types, which is
the only one subject to conscious control?
A. Smooth
B. Skeletal
C. Cardiac
D. All of these muscle types are subject to conscious control.
B. Skeletal
Which of the following muscular functions serves a metabolic function? A. Movement B. Posture maintenance C. Joint stabilization D. Heat generation
D. Heat generation
n order to receive a signal to contract, each skeletal muscle must be served by a(n) \_\_\_\_\_\_\_\_. A. artery B. nerve C. vein D. ligament
B. nerve
Which of the following components accounts for the bulk of muscle fiber volume (up to 80%)? A. Glycosomes B. Mitochondria C. Myofibrils D. Sarcoplasm
C. Myofibrils
The thin filaments are not comprised of which of the following components? A. Actin B. Titin C. Troponin D. Tropomyosin
B. Titin
What is the significance of the muscle fiber triad relationship?
A. The terminal cisterns subdivide the sarcolemma.
B. The T tubules bring calcium to the sarcoplasmic reticulum.
C. The sarcoplasmic reticulum transfers calcium to the T tubules.
D. The T tubules conduct electrical impulses that stimulate calcium release from the sarcoplasmic reticulum.
D. The T tubules conduct electrical impulses that stimulate calcium release from the sarcoplasmic reticulum.
During a muscle contraction, the sliding
filament theory would be apparent in a sarcomere because ______.
A. the I bands get longer
B. the A bands get shorter
C. the H zone becomes less obvious and the Z discs move closer together
D. the Z discs get pulled closer to the I bands and the H zone becomes more obvious
C. the H zone becomes less obvious and the Z discs move closer together
At the neuromuscular junction, the
muscle contraction initiation event is ______.
A. a release of calcium ions from the sarcoplasmic reticulum
B. conduction of an electrical impulse down the T tubules
C. binding of acetylcholine to membrane receptors on the sarcolemma
D. sliding of actin and myosin filaments past each other
C. binding of acetylcholine to membrane receptors on the sarcolemma
In a muscle fiber, the key intracellular event that stimulates muscle contraction is known as \_\_\_\_\_\_. A. polarization B. depolarization C. repolarization D. potential
B. depolarization
During depolarization, the sarcolemma is most permeable to \_\_\_\_\_\_. A. sodium ions B. potassium ions C. calcium ions D. chloride ions
A. sodium ions
What is calcium’s function during muscle
contraction?
A. Calcium binds to troponin, changing its shape and removing the blocking action of tropomyosin.
B. Calcium binds to troponin to prevent myosin from attaching to actin.
C. Calcium depolarizes the muscle fiber.
D. Calcium flows down the T tubules to stimulate the influx of sodium from the sarcoplasmic reticulum.
A. Calcium binds to troponin, changing its shape and removing the blocking action of tropomyosin.
Small precise movements are controlled by \_\_\_\_\_\_ motor units. A. small B. large C. many D. few
A. small
A sprinter is likely to depend on \_\_\_\_\_\_\_\_\_ respiration to generate ATP, and a Tour de France cyclist is likely to rely on \_\_\_\_\_\_\_\_\_\_ respiration. A. anaerobic; aerobic B. aerobic; anaerobic C. aerobic; aerobic D. anaerobic; anaerobic
A. anaerobic; aerobic
Sprinters typically possess more \_\_\_\_\_\_ muscle fibers. A. slow glycolytic B. fast glycolytic C. slow oxidative D. fast oxidative
D. fast oxidative
A major difference between smooth
muscle fibers and skeletal muscle fibers in terms of calcium influx is that ______.
A. smooth muscle fibers have a sarcoplasmic reticulum
B. calcium ions are stored in the sarcoplasm of smooth muscle
C. calcium ion influx occurs mostly from the extracellular fluid in smooth muscle
D. smooth muscle contraction does not involve calcium
C. calcium ion influx occurs mostly from the extracellular fluid in smooth muscle
A major cellular feature in smooth muscle that contributes to its rhythmicity and ability to participate in peristalsis is the presence of \_\_\_\_\_\_. A. troponin complex B. gap junctions C. varicosities D. caveolae
B. gap junctions
The principal neurotransmitter of skeletal
muscle is acetylcholine. The major neurotransmitter(s) of smooth muscle is (are) _______.
A. acetylcholine
B. epinephrine
C. norepinephrine
D. all of the above
D. all of the above
Electrical coupling by gap junctions is present in \_\_\_\_\_\_. A. multi unit smooth muscle B. skeletal muscle C. unitary smooth muscle D. bi-unit smooth muscle
C. unitary smooth muscle
