HSFtb Chapter 11

A deficiency of acetylcholine receptors leads to muscle paralysis in myasthenia gravis.

TRUE

An isometric contraction does not change muscle length.

TRUE

Clinically, dystrophin is the most important noncontractile protein to occur in muscle fibers.

TRUE

Extensibility refers to the ability of a muscle to stretch.

TRUE

Some smooth muscle is autorhythmic.

TRUE

The sarcoplasmic reticulum is the smooth endoplasmic reticulum of a muscle fiber.

TRUE

Which of the following individuals would have more mitochondria in her skeletal muscle? A. A 50-year-old sedentary computer programmer B. A 22-year-old soccer player C. A long-term hospice patient D. A model on a reduced-calorie diet E. A newborn

B. A 22-year-old soccer player

How many muscle fibers stimulate one somatic motor neuron? A. 0 B. 1 C. 2 D. 3 E. 4

A. 0

Which of the following contains overlapping thick and thin filaments? A. A band B. H band C. I band D. M line E. Z discs

A. A band

Where is dystrophin, the protein that is defective in muscular dystrophy, normally found? A. Between the outermost myofilaments and the sarcolemma of a muscle fiber B. As a transmembrane protein of the sarcolemma C. In the Z discs of skeletal and cardiac muscle D. In the dense bodies of smooth muscle E. Bridging the gap between the sarcolemma and axon terminal

A. Between the outermost myofilaments and the sarcolemma of a muscle fiber

Which of the following would be caused by a contraction of smooth muscle? A. Goose bumps B. Blood leaving the left ventricle of the heart C. Elevating the eyebrows D. Blinking the eyelids E. Deep inspiration

A. Goose bumps

Which of the following is not a characteristic of a muscle cell? A. Plasticity B. Contractility C. Conductivity D. Extensibility E. Excitability

A. Plasticity

Which muscle type depends solely on the sarcoplasmic reticulum as its calcium source? A. Skeletal muscle B. Smooth muscle C. Cardiac muscle D. Skeletal and smooth muscle E. Smooth and cardiac muscle

A. Skeletal muscle

Which of the following best describes the resting membrane potential (RMP)? A. The intracellular environment is negatively charged. B. The intracellular environment has more positively charged sodium. C. The extracellular environment is negatively charged. D. It has a voltage of about +75 mV. E. It is dependent upon the absorption of potassium ions by the muscle fiber.

A. The intracellular environment is negatively charged.

Which of the following is true concerning isotonic concentric contraction? A. The muscle shortens but tension remains constant. B. The muscle lengthens but tension remains constant. C. The muscle tenses and shortens. D. The muscle tenses but length remains unchanged. E. The muscle lengthens and tension declines.

A. The muscle shortens but tension remains constant.

Which of the following is not a purpose of the excess postexercise oxygen consumption (EPOC) in muscle? A. To neutralize carbon dioxide buildup B. To replenish the phosphagen system C. To oxidize lactate D. To serve elevated metabolic rate E. To restore resting levels of ATP and CP

A. To neutralize carbon dioxide buildup

A muscle twitch produces external tension and moves an object by shortening the muscles during the _____ phase. A. contraction B. latent C. twitch D. relaxation E. reload

A. contraction

All muscle types will respond to an electrical stimulus because all muscle cells are _________. A. excitable B. contractile C. striated D. involuntary E. isometric

A. excitable

As you are lifting a box, someone places extra weight on top of it. For your muscle to continue contracting and lifting the box, the muscle must __________. A. recruit more muscle fibers B. lower its threshold C. reduce its wave summation D. shift from isometric to isotonic contraction E. shift from slow-twitch to fast-twitch mode

A. recruit more muscle fibers

Cardiac muscle has very little capacity for regeneration because it lacks __________. A. satellite cells B. an endomysium C. sarcomeres D. dense bodies E. somatic nerve fibers

A. satellite cells

To stimulate muscle contraction, acetylcholine is released from the ___________ into the synaptic cleft. A. synaptic vesicles B. junctional folds C. sarcoplasmic reticulum D. sarcolemma E. terminal cisterns

A. synaptic vesicles

The minimum stimulus needed to cause muscle contraction is called the __________. A. threshold B. latent period C. twitch D. motor unit E. innervation

A. threshold

Why does one continue to breathe heavy after rigorous physical activity has stopped? A. The diaphragm is waiting for its acetylcholine to run out. B. The body requires more oxygen to restore levels of ATP and creatine phosphate. C. The lungs can't stop breathing until the heart rate slows down. D. Myosin heads need more oxygen to fully detach from actin. E. The kidneys require oxygen to dispose of excess lactate.

B. The body requires more oxygen to restore levels of ATP and creatine phosphate.

Which of the following is true concerning isotonic eccentric contraction? A. The muscle shortens but tension remains constant. B. The muscle lengthens but tension remains constant. C. The muscle tenses and shortens. D. The muscle tenses but length remains unchanged. E. The muscle lengthens and tension declines.

B. The muscle lengthens but tension remains constant.

What happens when acetylcholine stimulates its receptors in the neuromuscular junction? A. The release of Ca2+ from the sarcoplasmic reticulum decreases. B. The permeability of the sarcolemma to Na+ increases. C. The positive charge on the sarcolemma decreases. D. The threshold of the muscle fiber lowers. E. The inhibitory effect of acetylcholinesterase is overridden.

B. The permeability of the sarcolemma to Na+ increases.

When a skeletal muscle lengthens, its __________ helps resist excessive stretching and subsequent injury to the muscle. A. thick filaments B. collagen C. actin D. troponin-tropomyosin complex E. varicosities

B. collagen

The training regimen of a competitive weight lifter is designed partly to __________. A. convert certain parallel muscles into stronger pennate muscles B. increase the average number of myofibrils per muscle fiber C. convert white muscle tissue to red muscle D. increase the size of his motor units E. lower the threshold for muscle excitation

B. increase the average number of myofibrils per muscle fiber

80% of the lactate produced by skeletal muscle is converted to pyruvate by the __________. A. kidneys B. liver C. muscle tissue D. sarcoplasmic reticulum E. neuromuscular junction

B. liver

A skeletal muscle generates the greatest tension when it is __________. A. greatly stretched before being stimulated B. partially stretched before being stimulated C. fully relaxed before being stimulated D. well-rested and low in creatine phosphate E. high in lactate concentration

B. partially stretched before being stimulated

The sarcolemma of a resting muscle fiber is most permeable to __________. A. calcium B. potassium C. sodium D. lithium E. magnesium

B. potassium

The process of engaging more motor units to increase the strength of a muscle contraction is called __________. A. wave summation B. recruitment C. temporal summation D. incomplete tetanus E. complete tetanus

B. recruitment

In skeletal muscle, the term that describes the alternating light and dark bands is ___________. A. strabismus B. striations C. tetanus D. myofibrils E. myoblasts

B. striations

The absence or inhibition of acetylcholinesterase at a synapse would lead to __________. A. flaccid paralysis B. tetanus C. atrophy D. numbness E. muscle wasting

B. tetanus

Michael Jordan was arguably the best player in professional basketball history. Scientifically, one would expect him to have highly developed __________ fibers. A. red B. white C. intermediate D. fast twitch E. slow oxidative

B. white

Aerobic respiration produces approximately _________ more ATPs per glucose molecule than glycolysis does. A. 12 B. 24 C. 36 D. 48 E. 100

C. 36

During muscle contraction, a single myosin head consumes ATP at a rate of about __________ ATP per second. A. 1 B. 3 C. 5 D. 7 E. 9

C. 5

Which of the following has the largest mitochondria? A. Slow oxidative fibers B. Fast glycolytic fibers C. Cardiac muscle D. Smooth muscle E. Intermediate fibers

C. Cardiac muscle

Which of the following is a property of collagen? A. Contractility B. Excitability C. Elasticity D. Expendability E. Impermeability

C. Elasticity

Why is the contraction strength of smooth muscle relatively independent of its resting length? A. It gets nearly all of its Ca2+ from the extracellular fluid. B. It does not have intercalated discs. C. It does not have sarcomeres. D. It is regulated by a length-tension relationship. E. It is involuntary muscle.

C. It does not have sarcomeres.

In order for muscle to continue contracting during anaerobic fermentation, which of the following is essential? A. Cholinesterase inhibitors B. Protease C. Myokinase D. Acetylcholinesterase E. Acid phosphatase

C. Myokinase

Which of the following is an accurate comparison of skeletal muscle to smooth muscle? A. Smooth muscle contracts more slowly but relaxes more rapidly. B. Smooth muscle contracts more rapidly but relaxes more slowly. C. Smooth muscle contracts and relaxes more slowly. D. Smooth muscle consumes more ATP to maintain a given level of muscle tension. E. Smooth muscle depends on a nerve fiber to supply the calcium needed for contraction.

C. Smooth muscle contracts and relaxes more slowly.

Which of the following systems would provide energy for a racquetball player, while playing a point? A. The respiratory system B. The glycolysis system C. The phosphagen system D. The anaerobic system E. The glycogen-lactate system

C. The phosphagen system

Which fibers are primarily responsible for producing lactate? A. Type I slow oxidative fibers B. Type IIA intermediate glycolytic fibers C. Type IIB fast glycolytic fibers D. Type I slow-twitch fibers E. Red fibers

C. Type IIB fast glycolytic fibers

Which of the following marks the boundaries of a sarcomere? A. I bands B. H bands C. Z discs D. M lines E. A bands

C. Z discs

If one nerve stimulus arrives at a muscle fiber so soon that the fiber has only partially relaxed from the previous twitch, the most likely result will be __________. A. fatigue B. spasm C. incomplete tetanus D. complete tetanus E. flaccid paralysis

C. incomplete tetanus

Athletes who train at high altitudes increase their red blood cell count, which increases their oxygen supply during exercise. Increased oxygen supply results in __________. A. increased glycolysis B. increased use of myokinase C. longer aerobic respiration D. longer anaerobic fermentation E. reduced ATP consumption

C. longer aerobic respiration

When acetylcholinesterase outlasts the release of acetylcholine from the synaptic vesicles, the skeletal muscle __________. A. contracts B. gets stronger C. relaxes D. releases Ca2+ E. opens its Na+ channels

C. relaxes

The protein that acts as a calcium receptor in skeletal muscle is __________. A. F actin B. tropomyosin C. troponin D. titin E. dystrophin

C. troponin

The triads of a muscle fiber consist of __________. A. two A bands and one I band B. two T tubules and one terminal cistern C. two terminal cisterns and one T tubule D. two thin myofilaments and one thick myofilament E. two thick myofilaments and one thin myofilament

C. two terminal cisterns and one T tubule

Exposure to the bacterium Clostridium tetani causes continuous release of acetylcholine. What effect does this have on smooth muscle? A. Flaccid paralysis B. Spastic paralysis C. Lockjaw D. No effect E. Myocardial atrophy

D. No effect

Which muscle(s) can contract without the need for nervous stimulation? A. Skeletal muscle only B. Smooth muscle only C. Cardiac muscle only D. Smooth and cardiac muscle E. Skeletal, smooth and cardiac muscle

D. Smooth and cardiac muscle

Where would you expect to find numerous gap junctions in muscular tissue? A. The sarcoplasmic reticulum of skeletal muscle B. The A bands of skeletal and cardiac muscle C. The sarcolemma of skeletal muscle D. The intercalated discs of cardiac muscle E. Multiunit smooth muscle

D. The intercalated discs of cardiac muscle

The axon terminal releases acetylcholine into the synaptic cleft, which is received by receptors on the motor end plate. Which structure does this describe? A. A sarcomere B. The thick filament C. The varicosity of a smooth muscle cell D. The neuromuscular junction of a skeletal muscle E. A motor unit

D. The neuromuscular junction of a skeletal muscle

Which of the following is predominately made up of myosin? A. G actin B. F actin C. The thin filament D. The thick filament E. The elastic filament

D. The thick filament

A volleyball player depends on the gastrocnemius muscles for plantar flexion, whereas a marathon runner depends more on the soleus muscles for the same action. What characteristic of the soleus muscles makes this so? A. They have smaller mitochondria. B. They have more glycogen in them. C. They don't have as many blood capillaries per gram of tissue. D. They make more use of aerobic respiration. E. They break ATP down to ADP and Pi faster.

D. They make more use of aerobic respiration.

What is the purpose of motor nerve varicosities as they relate to smooth muscle? A. They link the thin filaments to the inside of the sarcolemma in smooth muscle. B. They reabsorb the decomposition products of acetylcholine after acetylcholinesterase breaks it down. C. They enable each cardiomyocyte to directly stimulate its neighbors. D. They release neurotransmitter molecules onto smooth muscle cells. E. They prevent single-unit smooth muscle cells from pulling apart.

D. They release neurotransmitter molecules onto smooth muscle cells.

Loss of muscle mass from lack of activity is called __________. A. myopathy B. dystrophy C. apathy D. atrophy E. tetanus

D. atrophy

If one nerve stimulus arrives at a muscle fiber so soon that the fiber does NOT relax at all from the previous twitch, the most likely result will be __________. This can only be achieved in the laboratory. A. fatigue B. spasm C. incomplete tetanus D. complete tetanus E. wave summation

D. complete tetanus

The transfer of phosphate from CP to ADP is catalyzed by __________. A. myokinase B. creatinine C. cAMP D. creatine kinase E. ATP

D. creatine kinase

Skeletal muscle is called ___________, because it is usually subject to conscious control. A. excitable B. contractile C. striated D. voluntary E. isometric

D. voluntary

What is the purpose of the triad? A. The triad stores sodium. B. The triad synthesizes ATP. C. The triad maintains the resting membrane potential. D. The triad removes acetylcholine from the synaptic cleft. E. The triad allows for Ca2+ release when a muscle fiber is excited.

E. The triad allows for Ca2+ release when a muscle fiber is excited.

Drugs called calcium channel blockers may be used to lower blood pressure by causing arteries to vasodilate. How do you suppose these drugs work? A. They prevent calcium from entering the sarcoplasmic reticulum of smooth muscle. B. They stimulate the calcium pump in smooth muscle, thus removing calcium from the calmodulin. C. They prevent calcium from exiting the sarcoplasmic reticulum in skeletal muscle. D. They prevent calcium from entering cardiac muscle, thus slowing down the heart rate. E. They prevent calcium from entering smooth muscle, thus allowing the muscle to relax.

E. They prevent calcium from entering smooth muscle, thus allowing the muscle to relax.

Which statement best describes the goal of medications used to treat myasthenia gravis? A. To increase the number of acetylcholine receptors B. To decrease the number of synaptic vesicles C. To promote multiple motor unit summation D. To inhibit Ca2+ release from the sarcoplasmic reticulum E. To inhibit the function of cholinesterase

E. To inhibit the function of cholinesterase

Shortening a muscle while it maintains constant tension is called __________. A. complete tetanus B. incomplete tetanus C. an isokinetic contraction D. an isometric contraction E. an isotonic contraction

E. an isotonic contraction

A myofilament that runs throught the core of a thick filament and anchors it to a Z disc is called a(n) __________. A. myofibril B. thin filament C. T tubule D. sarcolemma E. elastic filament

E. elastic filament

Resistance exercise will most likely cause muscle to __________. A. myopathy B. dystrophy C. apathy D. atrophy E. hypertrophy

E. hypertrophy

A dark band formed by parallel thick filaments that partly overlap the thin filaments is known as an H band.

FALSE

Skeletal muscle are attached to bones in a way that aligns proteins in an overly-stretch (lengthened) position. This lengthening facilitates the shortening of contractions.

FALSE

The sliding filament theory of muscle contraction has emerged from research only in the last 10 to 15 years.

FALSE