A&P Chp 11

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

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

An isometric contraction does not change muscle length

Some smooth muscle is autorhythmic.

80% of the lactic acid produced by skeletal muscle is converted to pyruvic acid by the _____ kidneys liver muscle tissue sarcoplasmsic reticulum neuromuscular junction

During muscle contraction, a single myosin head consumes ATP at a rate of about ________ ATP per second 1 3 5 7 9

Which fibers are primarily responsible for producing lactic acid? type I slow oxidative fibers type IIA intermediate glycolytic fibers type IIB fast glycolytic fibers type I slow-twitch fibers red fibers

Michael Jordan was arguably the best player in professional basketball history. Scientifically one would expect him to have highly developed _____ fibers red white intermediate fast twitch slow twitch

Why is the contraction strength of smooth muscle relatively independent of its resting length it gets nearly all of its Ca2+ from the extracellular fluid it does not have intercalated discs it does not have sarcomeres it is regulated by a length-tension relationship it is involuntary muscle

which of the following is an accurate comparison of skeletal muscle to smooth muscle smooth muscle contracts more slowly but relaxes more rapidly smooth muscle contracts more rapidly but relaxes more slowly smooth muscle contracts and relaxes more slowly smooth muscle consumes more ATP to maintain a given level of muscle tension smooth muscle depends on a nerve fiber to supply the calcium needed for contraction

In order for muscle to continue contraction during anaerobic respiration, which of the following is essential? cholinesterage inhibitors protease myokinase acetycholinesterase acid phosphatase

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 fatigue spasm incomplete tetanus complete tetanus flaccid paralysis

Which of the following is true concerning isotonic eccentric contraction? the muscle shortens but tension remains constant the muscle lengthens but tension remains constant the muscle tenses and shortens the muscle tenses but length remains unchanged the muscle lengthens and tension declines

How many muscle fibers stimulate one somatic motor neuron 0 1 2 3 4

The absence or inhibition of acetylcholinesterase at a synapse would lead to flaccid paralysis tetanus atrophy numbness muscle wasting

Cardiac muscle has very little capacity for regeneration because it lacks satellite cells an endomysium sarcomeres dense bodies somatic nerve fibers

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

Exposure to Clostridium tetani causes continuous release of acetylcholinr. What effect does this have on smooth muscle? flaccid paralysis spastic paralysis lockjaw no effect myocardial atrophy

Which of the following best describes the resting membrane potential (RMP)? the intracellular environment is negatively charged the intracellular environment has more positivily charged sodium the extracellular environment is negatively charged it has a voltage of about +75 mV it is dependent upon the absorption of potassium ions by the muscle fiber

The sarcolemma of a resting muscle fiber is most permeable to calcium potassium sodium lithium magnesium

Which of the following is a property of collagen contractability excitability elasticity expendability impermeablility

A myofilament that runs through the core of a thick filament and anchors it to a Z disc is called a (n) myofibril thin filament T tubule sarcolemma elastic 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 they have smaller mitochondria they have more glycogen in them they don't have as many blood capillaries per gram of tissue they make more use of aerobic respiration they break ATP down to ADP and Pi faster

Extensibility refers to the ability of a muscle to stretch

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

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

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

Which of the following marks the boundaries of a sarcomere? I bands H bands Z discs M lines A bands

Which of the following is predominately made up of myosin? G actin F actin the thin filament the thick filament the elastic filament

Which of the following contains overlapping thick and thin filaments? A band H band I band M line Z discs

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

Which muscle type depends solely on the sarcoplasmic reticulum as its calcium source? skeletal muscle smooth muscle cardiac muscle skeletal and smooth muscle smooth and cardiac muscle

Which muscle(s) can contract without the need for nervous stimulation? skeletal muscle smooth muscle cardiac muscle smooth and cardiac muscle skeletal, smooth and cardiac muscle

Where would you expect to find numerous gap junctions in muscular tissue? the sarcoplasmic reticulum of skeletal muscle the A bands of skeletal and cardiac muscle the sarcolemma of skeletal muscle intercalated discs of cardiac muscle multiunit smooth muscle

The minimum stimulus needed to cause muscle contraction is called the threshold. the latent period. twitch. recruitment. innervation.

Which of the following has the largest mitochondria? slow oxidative fibers fast glycolytic fibers cardiac muscle smooth muscle intermediate fibers

To stimulate muscle contraction, acetylcholine is released from the ___________ into the synaptic cleft. synaptic vesicles junctional folds sarcoplasmic reticulum sarcolemma terminal cisterna

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

The process of engaging more motor units to increase the strength of a muscle contraction is called wave summation. recruitment. treppe. incomplete tetanus. complete tetanus.

Aerobic respiration produces approximately _____ more ATPs per glucose molecule than glycolysis does. 12 24 36 48 100

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 increased glycolysis. increased use of myokinase. longer aerobic respiration. longer anaerobic fermentation. reduced ATP consumption.

Which of the following would be caused by contraction of smooth muscle? goose bumps blood leaving the left ventricle of the heart elevating the eyebrows blinking the eyelids deep inspiration

The triads of a muscle fiber consist of two A bands and one I band. two T tubules and one terminal cisterna. two terminal cisternae and one T tubule. two thin myofilaments and one thick myofilament. two thick myofilaments and one thin myofilament.

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 recruit more muscle fibers. lower its threshold. reduce its wave summation. shift from isometric to isotonic contraction. shift from slow-twitch to fast-twitch mode.

The protein that acts as a calcium receptor in skeletal muscle is F actin. tropomyosin. troponin. titin. dystrophin.

Where is dystrophin, the protein that is defective in muscular dystrophy, normally found between the outermost myofilaments and the sarcolemma of a muscle fiber. as a transmembrane protein of the sarcolemma. in the Z discs of skeletal and cardiac muscle. in the dense bodies of smooth muscle. bridging the gap between the sarcolemma and synaptic knob.

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

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

Which of the following systems would provide energy for a racquetball player, while playing a point the respiratory system the glycolysis system the phosphagen system the anaerobic system glycogen-lactic acid system

Loss of muscle mass from lack of activity is termed myopathy. dystrophy. apathy. atrophy. treppe.

Which of the following is NOT a characteristic of a muscle cell? plasticity contractility conductivity extensibility excitability

A skeletal muscle generates the greatest tension when it is greatly stretched before being stimulated. partially stretched before being stimulated. fully relaxed before being stimulated. well-rested and low in creatine phosphate. in a state of treppe.

In skeletal muscle, the term that describes alternating light and dark bands is strabismus. striations. treppe. myofibrils. myoblasts.

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

Skeletal muscle is called ______, because it is usually subject to conscious control excitable contractile striated voluntary isometric

Shortening a muscle while it maintains constant tension is called complete tetanus incomplete tetanus an isokinetic contraction an isometric contraction an isotonic contraction

The transfer of phospate from CP to ADP is catalyzed by myokinase creatinine cAMP creatine kinase ATP

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

What is the purpose of motor nerve varicosities as they relate to smooth muscle they link the thin filament to the inside of the sarcolemma in smooth muscle they reabsorb the decomposition products of acetylcholine after acetylcholinesterase breaks it down they enable each cardiac myocyte to directly stimulate its neighbor they release neurotransmitter onto smooth muscle cells they prevent sing;e-unit smooth muscle cells from pulling apart

All muscle types will respond to an electrical stimulus because all muscle cells are excitable contractile striated involuntary isometric

When a skeletal muscle lengthens, its ______ helps resist excessive stretching and subsequent injury to the muscle thick filaments collagen actin troponin-tropomyosin complex varicosities

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

When acetylcholinesterase outlasts the release of acetylcholine from the synaptic vesicles, the skeletal muscle contracts gets stronger relaxes releases Ca++ opens its Na+ channels

Why does one continue to breathe heavy after vigorus physical activity has stopped? the diaphragm is waiting for its acetylcholine to run out the body requires more oxygen to restore levels of ATP and creatine phosphate the lungs can't stop breathing until the heart rate slows down myosin heads need more oxygen to fully detach from actin the kidneys require oxygen to dispose of excess lactic acid