chpt11

One somatic motor neuron is stimulated by how many muscle fibers? A. 0 B. 1 C. 2 D. 3 E. 4

A. 0

A reason that muscle twitches become progressively stronger in treppe is A. Ca2+ accumulates in the sarcoplasm faster than the sarcoplasmic reticulum can reabsorb it. B. ATP is regenerated faster than it is consumed. C. myosin heads show faster and faster power strokes. D. more and more acetytlcholine is released with each stimulus. E. as the muscle warms up, aerobic respiration is accelerated.

A. Ca2+ accumulates in the sarcoplasm faster than the sarcoplasmic reticulum can reabsorb it.

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 depends on the muscle fiber absorbing potassium ions from the ECF.

A. The intracellular environment is negatively charged.

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

A. satellite cells

Dystrophin, the protein that is defective in muscular dystrophy, is 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 synaptic knob.

A. between the outermost myofilaments

80% of the lactic acid produced by skeletal muscle is converted to pyruvic acid A. by the kidneys B. in the liver C. in the muscle tissue D. in the sarcoplasmic reticulum

A. by the kidneys

Which of the following would be caused by 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

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.

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

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

A. synaptic knob

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

A. the threshold.

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

A. to neutralize carbon dioxide buildup

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.

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 football player C. a long-term hospice patient D. a model on a reduced-calorie diet E. a newborn

B. a 22-year-old football player

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.

Release of acetylcholine at a neuromuscular junction A. decreases the release of Ca2+ from the sarcoplasmic reticulum. B. increases permeability of the sarcolemma to Na+. C. decreases the positive charge on the sarcolemma. D. lowers the threshold of the muscle fiber. E. overrides the inhibitory effect of acetylcholinesterase.

B. increases permeability of the sarcolemma to Na+.

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. in a state of treppe.

B. partially stretched before being stimulated.

53.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 bringing more motor units into use during a muscle contraction is called A. wave summation. B. recruitment. C. treppe. D. incomplete tetanus. E. complete tetanus.

B. recruitment.

In skeletal muscle, alternating light and dark bands are termed A. strabismus. B. striations. C. treppe. D. myofibrils. E. myoblasts.

B. striations.

The absence or inhibition of acetylcholinesterase at a synapse would lead to which of the following? 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 A. red fibers. B. white fibers. C. intermediate fibers. D. fast-twitch fibers. E. slow oxidative fibers.

B. white fibers.

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

C. contracts and relaxes more slowly.

Collagen is A. contractile. B. excitable. C. elastic. D. expendable. E. impermeable.

C. elastic.

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 A. 1 ATP per second. B. 3 ATP per second. C. 5 ATP per second. D. 7 ATP per second. E. 9 ATP per second.

C. 5 ATP per second.

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

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. treppe. C. incomplete tetanus. D. complete tetanus. E. flaccid paralysis.

C. incomplete tetanus.

The contraction strength of smooth muscle is relatively independent of its resting length partly because 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.

Athletes who train at high altitudes increase their red blood cell count and thus increase 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.

Which of the following is very important for muscle to continue contraction during anaerobic respiration? A. cholinesterase inhibitors B. protease C. myokinase D. acetylcholinesterase E. acid phosphatase

C. myokinase

Which of the following systems would provide energy for a racquetball player? A. the respiratory system B. the glycolysis system C. the phosphagen system D. the anaerobic system E. glycogen-lactic acid system

C. the phosphagen system

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 cisterna. C. two terminal cisternae and one T tubule. D. two thin myofilaments and one thick myofilament. E. two thick myofilaments and one thin myofilament.

C. two terminal cisternae and one T tubule.

Which fibers are primarily responsible for producing lactic acid? 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

Loss of muscle mass from lack of activity is termed A. myopathy. B. dystrophy. C. apathy. D. atrophy. E. treppe.

D. atrophy.

Creatine kinase A. donates one of its phosphate groups to ADP. B. phosphorylates and activates certain enzymes in the sarcoplasm. C. acts as a second messenger in muscle fibers. D. catalyzes the transfer of phosphate from CP to ADP. E. functions as a substitute for ATP during anaerobic fermentation.

D. catalyzes the transfer of phosphate from CP to ADP.

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. intercalated discs of cardiac muscle E. multiunit smooth muscle

D. intercalated discs of cardiac muscle

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. This is because the soleus muscles A. have smaller mitochondria. B. have more glycogen in them. C. don't have as many blood capillaries per gram of tissue. D. make more use of aerobic respiration. E. break ATP down to ADP and Pi faster.

D. make more use of aerobic respiration.

Exposure to 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

The bladder's ability to greatly distend and return to normal tension is due to the ___ of smooth muscles. A. elasticity B. longevity C. tensile strength D. plasticity E. tone

D. plasticity

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

D. smooth and cardiac muscle

The purpose of varicosities in motor nerve fibers in muscle physiology is A. to link the thin filaments to the inside of the sarcolemma in smooth muscle. B. to reabsorb the decomposition products of acetylcholine after acetylcholinesterase breaks it down. C. to enable each cardiac myocyte to directly stimulate its neighbors. D. to release neurotransmitter onto smooth muscle cells. E. to prevent single-unit smooth muscle cells from pulling apart.

D. to release neurotransmitter onto smooth muscle cells.

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.

A myofilament that flanks a thick filament and anchors it to a Z disc is called A. a myofibril. B. a thin filament. C. a myoglobin. D. a sarcoplasm. E. an elastic filament.

E. an elastic filament.

The term for shortening of a muscle while maintaining constant tension is A. treppe. B. tetanus. C. isokinetic contraction. D. isometric contraction. E. isotonic contraction.

E. isotonic contraction.

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

E. 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