Quiz 9: Muscular System

Functions of muscles include A) heartbeat. B) muscle tone. C) moving bones. D) all of the above.

The outermost layer of connective tissue surrounding a skeletal muscle is the A) epimysium. B) perimysium. C) endomysium. D) sarcomysium.

Myofibrils are composed primarily of A) actin and myosin. B) perimysium and endomysium. C) troponin and tropomyosin. D) fascia and tendons.

The striated appearance of skeletal muscle fibers results from the A) transverse tubule pattern. B) sarcoplasmic reticulum network. C) sarcomere organization. D) cisternae placement.

A sarcomere is best described as A) a part of the sarcoplasmic reticulum. B) a group of fascicles. C) a group of muscle fibers. D) a unit within a muscle fiber.

Transverse tubules A) store sodium ions for the action potential at the cell surface. B) transmit muscle impulses into the cell interior. C) store calcium ions. D) connect actin and myosin.

The discoloration and swelling of a muscle strain is due to A) excess myofibrils. B) separated tendons. C) severed nerves. D) ruptured blood vessels.

A tendon is ______, whereas an aponeurosis is ______. A) cordlike and connects bones to bones; a broad sheet of dense connective tissue that connects muscles to muscles B) a broad sheet of dense connective tissue that connects muscles to muscles; cordlike and connects bones to bones C) cordlike and connects muscles to bones; a broad sheet of dense connective tissue that connects muscles to muscles D) a broad sheet of dense connective tissue that connects bones to bones; cordlike and connects muscles to muscles

Muscle fibers are basically a collection of A) muscles. B) sarcomeres. C) connective tissue fibers. D) synapses.

Transverse tubules and sarcoplasmic reticulum are well developed in A) smooth muscle fibers. B) skeletal muscle fibers. C) cardiac muscle fibers. D) skeletal and cardiac muscle fibers.

The functional unit of muscle contraction is A) the muscle. B) the muscle fiber. C) the myosin cross-bridge. D) the sarcomere.

Neurotransmitters are stored in vesicles in A) myofibrils. B) motor units. C) motor end plates. D) motor neuron endings.

The enzyme acetylecholinesterase causes acetylcholine to A) bind to actin. B) be secreted from the motor end plate. C) decompose. D) form cross-bridges.

Creatine phosphate A) causes the decomposition of ATP. B) causes the decomposition of ADP. C) supplies energy for the synthesis of ATP. D) supplies energy for the breakdown of ATP to ADP.

The amount of oxygen liver cells require to support the conversion of lactic acid to produce glucose or glycogen is the A) refractory quantity. B) oxygen debt. C) anaerobic concentration. D) aerobic conversion.

Tawanda finishes a sprint and suffers great pain in her calf muscles. Her muscle cramps are most likely due to a temporary deficit of A) actin. B) myosin. C) ATP. D) ADP.

Binding sites on the surface of actin allow the formation of cross-bridges with molecules of A) ATP. B) myosin. C) troponin. D) tropomyosin.

Athletes usually experience muscle fatigue less quickly than nonathletes because they A) convert glucose to lactic acid. B) tolerate high concentrations of carbon dioxide. C) make more efficient use of ATP. D) produce less lactic acid.

At a neuromuscular junction, the muscle fiber membrane folds, forming a A) motor neuron. B) neurotransmitter. C) motor unit. D) motor end plate.

The toxin that causes botulism A) prevents release of acetylcholine. B) promotes release of acetylcholine. C) decomposes acetylcholine. D) prevents decomposition of acetylcholine.

Rigor mortis affects skeletal muscles a few hours after death, due to A) an increase in ATP and decreased permeability to calcium. B) a decrease in ATP and increased permeability to calcium. C) an increase in ATP. D) impulses that produce sustained contractions.

At a neuromuscular junction A) actin and myosin filaments slide past one another. B) troponin and tropomyosin exchange places. C) neurotransmitters are released. D) intercalated discs are synthesized.

The first event in muscle fiber contraction is that A) the muscle fiber membrane is stimulated and a muscle impulse travels deep into the fiber through transverse tubules. B) acetylcholine diffuses across a gap at a neuromuscular junction. C) acetylcholine is released from the end of the motor neuron. D) calcium ions diffuse from sarcoplasmic reticulum into the sarcoplasm and bind to troponin molecules.

Which of the following statements is correct? A) Tropomyosin molecules move and expose specific sites on myosin filaments. B) Actin filaments slide along myosin filaments. C) Cross-bridges form between actin and the sarcolemma. D) Filaments of troponin and tropomyosin slide past one another.

The functional connection between a neuron and a skeletal muscle fiber is a A) synapse. B) fascia. C) neuroma. D) dendrite.

__________ degrades acetylcholine, keeping it from accumulating in the synapse. A) ATPase B) Myosinase C) Actinase D) Acetylcholinesterase

Arrange the following steps of muscle fiber contraction in the correct sequence. 1) The muscle impulse reaches the sarcoplasmic reticulum and calcium is released. 2) Thin filaments are pulled over the thick filaments. 3) Calcium floods the sarcoplasm and binds to troponin molecules leaving active sites. 4) The impulse arrives at the synapse and travels through the transverse tubules. 5) The muscle fiber shortens and contracts. 6) Myosin heads bind to exposed active sites on actin, forming cross-bridges. 7-30-2013 A) 4, 1, 3, 5, 6, 2 B) 4, 1, 3, 2, 6, 5 C) 4, 1, 3, 6, 2, 5 D) 4, 3, 6, 2, 5, 1

A shift in metabolism that breaks down pyruvic acid to lactic acid is called A) aerobic threshold. B) lactic acid threshold. C) pyruvic acid threshold. D) glycogenic threshold.

Oxygen debt in muscles may develop because of A) the inability of respiratory and circulatory systems to supply enough oxygen to skeletal muscles when used strenuously for a minute or two. B) the inability of myoglobin molecules to store enough oxygen when skeletal muscles are used strenuously for a minute or two. C) too much oxygen used in forming pyruvic acid when skeletal muscles are contracted strenuously for a minute or two. D) too high a concentration of oxygen in the atmosphere.

When ATP levels are low, the relationship between ATP and creatine phosphate is that A) ATP supplies energy to synthesize creatine phosphate from creatine and phosphate. B) creatine phosphate supplies energy to regenerate ATP from ADP and phosphate. C) both have three phosphate groups. D) both are required to stimulate a muscle to contract.

The characteristic reddish brown color of skeletal muscle comes from which substance? A) Actin B) Myosin C) Myoglobin D) Calcium

A motor unit is A) many myofibrils in a sarcolemma. B) many motor end plates at a neuromuscular junction. C) a motor neuron and the muscle fibers connected to it. D) the functional unit of a muscle fiber.

During muscle contraction ATP supplies energy for A) creatine phosphate synthesis. B) glycogen synthesis. C) myofilament movement. D) enzyme activity.

Skeletal muscles help maintain body temperature in that A) the more active they are, the more heat is used up. B) the more active they are, the more heat is released. C) excess myosin is quickly metabolized to yield heat. D) they conserve actin and myosin in cold weather.

Threshold stimulus is the A) maximum stimulus required to release acetylcholine. B) minimum stimulus required to produce ATP. C) maximum stimulus required to contract a muscle. D) minimum strength of stimulation required to contract a muscle fiber.

A myogram is A) a chart that shows how many muscle cells a neuron synapses with. B) a recording of the events of a twitch. C) a measurement of muscle tone. D) a depiction of the results of a stress test.

A plank position is part of a yoga/Pilates workout. The person supports the body on the floor in a prone position with the arms and feet supporting the body. It is a little like the "up" position of a push-up, held for 30 to 60 seconds. Contraction of the abdominal muscles in a plank is most likely A) isotonic. B) eccentric. C) isometric. D) concentric.

An example of a partial but sustained contraction is A) knee jerking. B) muscle tone. C) a twitch. D) eye blinking.

Which of the following is not true? A) Red fibers contract more slowly than white. B) Red fibers contain more myoglobin than white. C) Red fibers have fewer mitochondria than white. D) Red fibers fatigue more slowly than white.

The increase in the number of motor units activated as a result of more intense stimulation is called A) latency. B) recruitment. C) threshold stimulation. D) sustained contraction.

In a recording of a muscle twitch, the delay between the time a stimulus is applied and the time the muscle responds is called the A) refractory period. B) relaxation period. C) latent period. D) contraction period.

A muscle fiber exposed to a series of stimuli of increasing frequency combines individual twitches (summation) which results in A) complete sustained contraction. B) muscle tone. C) a latent period. D) flaccid muscles.

Activities such as distance swimming and distance running are most likely to stimulate development of A) slow fatigable muscle fibers. B) fast fatigable muscle fibers. C) slow fatigue-resistant fibers. D) fast fatigue-resistant fibers.

Smooth muscle lacks A) actin and myosin. B) transverse tubules and striations. C) myofibrils. D) nuclei and mitochondria.

Smooth muscle has ___________ and not troponin. A) calmodulin B) fibronectin C) norepinephrine D) titin

When a muscle undergoes atrophy in response to disuse A) there is a reduction in capillary networks. B) the size of actin and myosin filaments decreases. C) the muscle gets smaller. D) all of the above.

Compared to skeletal muscle, smooth muscle A) contracts more slowly and relaxes more slowly. B) contracts more slowly and relaxes more rapidly. C) contracts more rapidly and relaxes more slowly. D) contracts more rapidly and relaxes more rapidly.

The type of muscle cell that lacks transverse tubules, has a single nucleus, and is under involuntary control is A) skeletal muscle. B) smooth muscle. C) cardiac muscle. D) striated muscle.

Short muscle cells with centrally located nuclei are A) smooth muscle fibers. B) skeletal muscle fibers. C) cardiac muscle fibers. D) striated muscle fibers.

Both acetylcholine and norepinephrine can affect A) smooth muscle contraction. B) skeletal muscle contraction. C) synthesis of actin and myosin. D) exercise tolerance.

The structures that connect cardiac muscle cells are A) intervertebral discs. B) neuromuscular junctions. C) intercalated discs. D) motor end plates.

Cardiac muscle A) contracts as a syncytium. B) excites itself. C) is only in the heart. D) all of the above.

Bones and muscles function as mechanical devices called A) lifts. B) levers. C) syncytia. D) ladders.

The more movable end of a muscle is its A) origin. B) fulcrum. C) insertion. D) source.

The muscle that causes an action is the A) synergist. B) antagonist. C) agonist. D) mediator.

A muscle that assists the agonist is a(n) A) antagonist. B) prime mover. C) mediator. D) synergist.

The buccinator muscle is in the A) buttocks. B) chest. C) bladder. D) cheek.

The muscle that adducts and flexes the arm is the A) coracobrachialis. B) pectoralis minor. C) levator scapulae. D) teres major.

The muscle that opposes a particular action is called the A) synergist. B) antagonist. C) agonist. D) prime mover.

The linea alba is A) a muscle extending from the ischial spine to the coccyx and sacrum. B) a curved, broad muscle on the side of the chest. C) a muscle beneath the skull. D) a band of tough connective tissue to which abdominal wall muscles attach.

The soleus is a muscle that forms part of the A) calf. B) buttocks. C) thigh. D) shoulder.

Which of the following is not a muscle of mastication? A) Medial and lateral pterygoid B) Masseter C) Temporalis D) Zygomaticus

Which of the following is unique in that its insertion is to fascia and not bone? A) palmaris longus B) extensor carpi ulnaris C) flexor digitorum profundus D) extensor digitorum

The triangle of auscultation, commonly used to hear sounds of respiratory organs, is located near the border of the A) pectoralis major and pectoralis minor. B) trapezius and latissimus dorsi. C) latissimus dorsi and serratus anterior. D) pectoralis major and serratus anterior.

A gluteal gait, in which a person walks with a waddling limp, is usually caused by a disorder of the A) gluteus maximus and gluteus medius. B) gluteus maximus and gluteus minimus. C) gluteus medius and gluteus minimus. D) gluteus maximus and tensor fasciae latae.

A sign of aging of the muscular system is A) expansion of muscle fiber diameters. B) decreased supplies of myoglobin to muscles. C) excess ATP. D) increased creatine phosphate.

Regina began an exercise program six months ago, and the muscles of her upper limbs and lower limbs are more prominent. Exercise can lead to formation of new muscle by A) stimulating synthesis of myoglobin. B) stimulating skeletal muscle cells to release IL-6, which stimulates satellite cells to divide, producing more muscle cells. C) stimulating connective tissue to differentiate as muscle tissue. D) stimulating motor neurons to divide and innervate more muscle cells.

Muscle atrophy that progresses with aging is caused by reduction in A) ATP. B) myoglobin. C) the sizes of muscle fibers. D) all of the above.

People with myasthenia gravis have a deficiency of A) titin molecules. B) troponin molecules. C) acetylcholine receptors D) sarcomeres.

Myasthenia gravis is A) an autoimmune disorder. B) a bacterial infection. C) a form of cancer. D) the result of injury.

A weightlifter uses muscles so the muscles exert more than 75% of their maximum tension, This stimulates A) an increase in slow, fatigable white fibers. B) muscle fibers developing new filaments of actin and myosin. C) shrinking of skeletal muscle. D) conversion of skeletal to smooth muscle.

Fibers of muscles whose motor neurons are severed A) hypertrophy. B) may be replaced by fat or fibrous connective tissue. C) cannot ever be reinnervated. D) die as their sarcomeres are progressively eliminated.

Temporomandibular joint (TMJ) syndrome causes A) headache. B) ringing in the ears. C) clicking sound from the jaw. D) all of the above.

Endomysium separates individual muscle fibers from each other.

A motor neuron and the muscle fibers that it controls constitute a motor unit.

In the initiation of muscle fiber contraction, calcium ions bind to tropomyosin, exposing active sites on actin for cross-bridge formation.

The enzyme ATPase occurs in the globular portion of myosin molecules.

Acetylcholine released by the myofibril crosses the synaptic cleft to bind to the motor neuron ending.

ATP is necessary for muscle relaxation.

A broad sheet of dense connective tissue that attaches the coverings of adjacent muscles is called an ______.

The pigment responsible for the reddish brown color of skeletal muscle is ______.

In order to stimulate skeletal muscle fibers, motor neurons release the neurotransmitter ______.

A forceful, sustained muscle contraction is called a ______ ______.

Muscle fatigue is most likely due to an accumulation of ______ ______.

The combining of a series of twitches to produce a more forceful contraction is called ______.

The rhythmic, wavelike motion produced by smooth muscles in tubular visceral organs is called _______.

The ______ ______ at the ends of cardiac muscle cells help to join cells.

Muscles that assist an agonist are called ______.

The muscle that covers the upper part of the cranium is the _______________.