a&p 1 chapter 9 quiz

When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods? A) relaxation period B) refractory period C) latent period D) fatigue period

B) refractory period

If given the exact same amount of ATP, which of the three fiber types would be able to contract for the longest amount of time? A) fast glycolytic fibers B) slow oxidative fibers C) both fast glycolytic and fast oxidative fibers D) fast oxidative fibers

B) slow oxidative fibers

The thin filaments (actin) contain a polypeptide subunit G actin that bears active sites for myosin attachment. True False

True

When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands do not diminish in length. True False

True

Which of the following is true about smooth muscle? A) Certain smooth muscle cells can actually divide to increase their numbers. B) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements. C) Smooth muscle cannot stretch as much as skeletal muscle. D) Smooth muscle has well-developed T tubules at the site of invagination.

A) Certain smooth muscle cells can actually divide to increase their numbers.

The force of muscle contraction is controlled by multiple motor unit summation or recruitment. True False

True

If a muscle fiber were to suddenly and permanently stop producing ATP the fiber would no longer be able to actively transport calcium out of the cytoplasm (sarcoplasm) and the intracellular calcium concentration would rise. Which of the following would you expect to happen? A) Myosin would be able to bind to the exposed binding sites on thin filaments but it would not be able to detach. B) The fiber would twitch uncontrollably due to excessive calcium bound to troponin. C) Calcium would be transported to the sarcoplasmic reticulum therefore contractions would cease. D) No change would occur in a muscle that was relaxed to begin with.

A) Myosin would be able to bind to the exposed binding sites on thin filaments but it would not be able to detach.

Of the following items listed below, which is the best description for why skeletal muscle stores glycogen? A) Skeletal muscle is a heavy consumer of energy. B) Glycogen provides a smooth surface for filaments to slide on. C) The glycogen is an insulating layer that helps regulate body temperature. D) Glycogen is part of muscles rigid supporting framework.

A) Skeletal muscle is a heavy consumer of energy.

The 100-meter dash is a quick and short run requiring explosive speed. On completion of the dash, the runners will continue to breathe hard for several seconds to minutes even though they are no longer running. Which of the following is the best explanation for why this is so? A) The runners' use of stored oxygen, glucose, and creatine phosphate is being replenished and this requires a prolonged increase of oxygen intake. B) Since the exercise was mostly aerobic exercise, the runners' bodies have not yet realized the run is over. C) The runners' fast oxidative muscles are so slow to utilize oxygen, they only begin aerobic respiration by the time the run has finished. D) Slow oxidative fibers are recruited last and have only started to work at completion of the run.

A) The runners' use of stored oxygen, glucose, and creatine phosphate is being replenished and this requires a prolonged increase of oxygen intake.

Although all the anatomical parts of muscle work together to give it it's characteristics, which of the following proteins listed below would be most associated with the characteristics of excitability? A) acetylcholine receptors in the motor end plate B) elastic (titin) filaments C) actin of thin filaments D) the Na+-K+ pump

A) acetylcholine receptors in the motor end plate

The sliding filament model of contraction involves ________. A) actin and myosin sliding past each other and partially overlapping B) the shortening of thick filaments so that thin filaments slide past C) actin and myosin lengthening in order to slide past each other D) the Z discs sliding over the myofilaments

A) actin and myosin sliding past each other and partially overlapping

In an isotonic contraction, the muscle ________. A) changes in length and moves the "load" B) does not change in length but increases tension C) never converts pyruvate to lactate D) rapidly resynthesizes creatine phosphate and ATP

A) changes in length and moves the "load"

What part of the sarcolemma contains acetylcholine receptors? A) motor end plate B) end of the muscle fiber C) part adjacent to another muscle cell D) any part of the sarcolemma

A) motor end plate

Which of the following is the correct sequence of events for muscle contractions? A) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments B) neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke C) muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments D) neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke

A) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

What is the primary function of wave summation? A) produce smooth, continuous muscle contraction B) increase muscle tension C) prevent muscle relaxation D) prevent muscle fatigue

A) produce smooth, continuous muscle contraction

What structure in skeletal muscle cells functions in calcium storage? A) sarcoplasmic reticulum B) mitochondria C) intermediate filament network D) myofibrillar network

A) sarcoplasmic reticulum

Reduction in blood flow to a muscle fiber would have the greatest effect on ________. A) slow oxidative fibers B) fast glycolytic C) both slow and fast oxidative D) fast oxidative fibers

A) slow oxidative fibers

Oxygen starved tissues can release chemical signals into the blood that can change the diameter of nearby blood vessels delivering oxygen and nutrients to the tissues. In doing so, the blood vessels will respond through vasodilation (widening of the vessel). Which muscle type is responsible for this vasodilation? A) smooth muscle B) cardiac muscle C) skeletal muscle D) striated muscle

A) smooth muscle

When a sarcomere contracts and thin filaments move over thick filaments you would expect to see ________. A) the I bands to appear smaller B) the H zone to appear wider C) the I bands to appear wider D) the A band to appear darker

A) the I bands to appear smaller

A potential benefit of recruiting slow oxidative fibers for contraction before recruiting fast oxidative and fast glycolytic fibers might be ________. A) to allow for fine control with delicate contractile force with a small stimulus B) because they are slower to respond, slow oxidative fibers must be stimulated first in order to contract simultaneously with the faster fibers C) recruiting slow oxidative fibers early helps to tire them out first so that they won't interfere with the more powerful contractions of fast glycolytic fibers D) There is little to no benefit from recruiting slow oxidative fibers first, and therefore it is in fact fast glycolytic fibers that will be recruited first.

A) to allow for fine control with delicate contractile force with a small stimulus

Myasthenia gravis is a disease that is believed to be caused by autoimmune disorder, resulting in the loss of ACh receptors at the motor end plate of muscle fibers. Which of the following is likely to be a symptom of myasthenia gravis? A) weakness of muscle B) seizures and uncontrollable muscle movement C) coma and loss of voluntary muscle movement D) dehydration with headache

A) weakness of muscle

What is the role of tropomyosin in skeletal muscles? A) Tropomyosin is the chemical that activates the myosin heads. B) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules. C) Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules. D) Tropomyosin is the receptor for the motor neuron neurotransmitter.

B) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.

Most skeletal muscles contain ________. A) muscle fibers of the same type B) a mixture of fiber types C) a predominance of slow oxidative fibers D) a predominance of fast oxidative fibers

B) a mixture of fiber types

During muscle contraction, myosin cross bridges attach to which active sites? A) myosin filaments B) actin filaments C) Z discs D) thick filaments

B) actin filaments

Although all the anatomical parts of muscle work together to give it its characteristics, which of the following proteins listed below would be most associated with the characteristics of extensibility? A) acetylcholine receptors in the motor end plate B) elastic (titin) filaments C) thick (myosin) filaments D) potassium (K+) leak channels

B) elastic (titin) filaments

Which of the following surrounds an individual muscle cell? A) perimysium B) endomysium C) epimysium D) fascicle

B) endomysium

What is the functional role of the T tubules? A) stabilize the G and F actin B) enhance cellular communication during muscle contraction C) hold cross bridges in place in a resting muscle D) synthesize ATP to provide energy for muscle contraction

B) enhance cellular communication during muscle contraction

Exhaustion of glycogen storage within a muscle fiber would have the biggest effect on ________. A) slow oxidative fibers B) fast glycolytic fibers C) both slow and fast oxidative fibers D) fast oxidative fibers

B) fast glycolytic fibers

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________. A) the citric acid cycle B) glycolysis C) hydrolysis D) the electron transport chain

B) glycolysis

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, ________. A) cross bridge attachment would be optimum because of all the free binding sites on actin B) no muscle tension could be generated C) maximum force production would result because the muscle has a maximum range of travel D) ATP consumption would increase because the sarcomere is "trying" to contract

B) no muscle tension could be generated

What does excess post-exercise oxygen consumption represent? A) amount of oxygen needed for aerobic activity to accomplish the same amount of work B) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used C) the amount of oxygen equal to the oxygen already used D) the amount of oxygen taken into the body immediately after the exertion

B) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used

Curare is a poisonous plant extract. Curare molecules have a chemical structure like the neurotransmitter ACh. Curare can bind to the ACh receptor site on the chemically gated ion channels in the motor end plate. Even though curare will bind to the receptor site it will not open the ion channel and no ions will pass through. What do you think the symptoms of curare poisoning would look like? A) Muscles will respond too quickly and cause a severe tremor. B) Curare will only affect cardiac muscle, causing fibrillations of the heart. C) Curare will only affect muscles with ACh receptors, paralyzing them. D) Smooth muscles will become stimulated causing quick movement of nutrients through the digestive system.

C) Curare will only affect muscles with ACh receptors, paralyzing them.

Troponin, a major protein in thin filaments, is a globular protein with three polypeptide subunits. Which of the following is NOT a function of the troponin? A) One subunit attaches troponin to actin. B) One subunit binds tropomyosin and helps position it on actin. C) One subunit binds to potassium ions. D) One subunit binds to calcium ions.

C) One subunit binds to potassium ions.

Which of the following statements is true? A) Cardiac muscle cells have many nuclei. B) Smooth muscle cells have T tubules. C) Striated muscle cells are long and cylindrical with many nuclei. D) Cardiac muscle cells are found in the heart and large blood vessels.

C) Striated muscle cells are long and cylindrical with many nuclei.

Which of the following describes the cells of unitary smooth muscle? A) They depend upon recruitment using the autonomic nervous system. B) They are used for vision and hair raising. C) They exhibit spontaneous action potentials. D) They consist of muscle fibers that are structurally independent of each other.

C) They exhibit spontaneous action potentials.

Muscle tone is ________. A) the ability of a muscle to efficiently cause skeletal movements B) the feeling of well-being following exercise C) a state of sustained partial contraction D) the condition of athletes after intensive training

C) a state of sustained partial contraction

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction? A) calcium ions returning to the terminal cisternae B) the tropomyosin blocking the myosin once full contraction is achieved C) acetylcholinesterase breaks apart the ACh D) the action potential stops going down the overloaded T tubules

C) acetylcholinesterase breaks apart the ACh

Addition of more mitochondria to a muscle fiber will have the greatest effect on ________. A) slow oxidative fibers B) fast glycolytic fibers C) both slow and fast oxidative fibers D) fast oxidative fibers

C) both slow and fast oxidative fibers

The ability of muscle to shorten forcibly when adequately stimulated is known as ________, and sets muscle apart from other tissue types. A) excitability B) extensibility C) contractility D) elasticity

C) contractility

Addition of more myoglobin to a muscle fiber would have the largest effect on ________. A) fast glycolytic and fast oxidative fibers B) fast oxidative fibers only C) fast oxidative and slow oxidative fibers D) fast glycolytic fibers only

C) fast oxidative and slow oxidative fibers

The strongest muscle contractions are normally achieved by ________. A) increasing stimulus above the threshold B) increasing stimulus above the treppe stimulus C) increasing the stimulation up to the maximal stimulus D) recruiting small and medium muscle fibers

C) increasing the stimulation up to the maximal stimulus

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors. A) contraction B) relaxation C) latent D) refractory

C) latent

Which of the following is the correct order for the phases of a muscle twitch? A) relaxation, contraction, latent B) contraction, relaxation, latent C) latent, contraction, relaxation D) latent, relaxation, contraction

C) latent, contraction, relaxation

Which of the following is a factor that affects the velocity and duration of muscle contraction? A) number of muscle fibers stimulated B) size of the muscle fibers stimulated C) load on the fiber D) muscle length

C) load on the fiber

The oxygen-binding protein found in muscle cells is ________. A) hemoglobin B) ATP C) myoglobin D) immunoglobin

C) myoglobin

Rigor mortis occurs because ________. A) the cells are dead B) sodium ions leak into the muscle causing continued contractions C) no ATP is available to release attached actin and myosin molecules D) proteins are beginning to break down, thus preventing a flow of calcium ions

C) no ATP is available to release attached actin and myosin molecules

Approximately 80% of a muscle fiber's volume are the myofibrils. This characteristic reflects muscles ability to ________. A) produce relatively high amounts of ATP B) store oxygen molecules that can be used in aerobic respiration C) produce movement through contractile force D) generate and propagate action potential

C) produce movement through contractile force

Which muscle cells have the greatest ability to regenerate? A) skeletal B) cardiac C) smooth D) no muscle can regenerate

C) smooth

Myoglobin ________. A) breaks down glycogen B) is a protein involved in the direct phosphorylation of ADP C) stores oxygen in muscle cells D) produces the end plate potential

C) stores oxygen in muscle cells

The mechanism of contraction in smooth muscle is different from skeletal muscle in that ________. A) actin and myosin interact by the sliding filament mechanism B) the trigger for contraction is a rise in intracellular calcium C) the site of calcium binding site differs D) ATP energizes the sliding process

C) the site of calcium binding site differs

Although all the anatomical parts of muscle work together to give it it's characteristics, which of the following proteins listed below would be most associated with the characteristics of contractility? A) voltage gated sodium channels B) elastic (titin) filaments C) thick (myosin) filaments D) potassium (K+) leak channels

C) thick (myosin) filaments

Sarcomeres are functional units of ________ muscle. A) smooth B) cardiac C) skeletal D) B and C only

D) B and C only

Which of the following statements best illustrates the fact that skeletal muscle is voluntary muscle? A) Skeletal muscle appears striated due to the structure of the sarcomeres. B) Skeletal muscle is wrapped in several layers of connective tissue. The deepest layer being the endomysium. C) The shivering reflex aids in maintaining body temperature. D) Skeletal muscle fibers are innervated by somatic motor neurons.

D) Skeletal muscle fibers are innervated by somatic motor neurons.

During vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to ________. A) a strong base B) stearic acid C) hydrochloric acid D) lactic acid

D) lactic acid

Which of the following would be recruited later in muscle stimulation when contractile strength increases? A) motor units with the longest muscle fibers B) many small motor units with the ability to stimulate other motor units C) large motor units with small, highly excitable neurons D) motor units with larger, less excitable neurons

D) motor units with larger, less excitable neurons

During development embryonic cells will fuse to form muscle fibers. This will result in ________. A) interlocking of cells that can prevent the filaments from sliding B) the coordination of nerve signals to muscle fibers C) the striations that appear in skeletal and cardiac muscle tissues D) multinucleated muscle fibers that can extend as long as 30 centimeters

D) multinucleated muscle fibers that can extend as long as 30 centimeters

The contractile units of skeletal muscles are ________. A) microtubules B) mitochondria C) T tubules D) myofibrils

D) myofibrils

Of the following muscle types, which has the longest muscle cells and has obvious stripes called striations? A) visceral smooth muscle B) multiunit smooth muscle C) cardiac muscle D) skeletal muscle

D) skeletal muscle

Creatine phosphate functions in the muscle cell by ________. A) forming a temporary chemical compound with myosin B) forming a chemical compound with actin C) inducing a conformational change in the myofilaments D) storing energy that will be transferred to ADP to resynthesize ATP

D) storing energy that will be transferred to ADP to resynthesize ATP

What is the most distinguishing characteristic of muscle tissue? A) It is composed of multiple cells working together. B) the ability to respond to nervous stimulation C) its cells' inability to reproduce by mitosis D) the ability to transform chemical energy into mechanical energy to move the body

D) the ability to transform chemical energy into mechanical energy to move the body

A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate. True False

False

During isometric contraction, the energy used appears as movement. True False

False

Muscle contraction will always promote movement of body parts regardless of how they are attached. True False

False

Once a motor neuron has fired, all the muscle fibers in a muscle contract. True False

False

The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily. True False

True

A contraction in which the muscle does not shorten but its tension increases is called isometric contraction. True False

True

A skeletal muscle contracts with varying force and length of time in response to the body's needs at the time. True False

True

Although there are no sarcomeres, smooth muscle still possesses thick and thin filaments. True False

True

An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops. True False

True

Cardiac muscle has a limited regenerative capacity True False

True

Cells of unitary smooth muscle are found in the longitudinal and circular muscle layers of the intestine. True False

True

Excitability is the ability of a cell to receive and respond to stimulus by changing its membrane potential. True False

True

Muscle cells store more creatine phosphate than ATP resulting in the muscle having a reserve source of energy. True False

True

Muscle tone is the small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units. True False

True

One of the functions of skeletal muscle contraction is production of heat. True False

True

Peristalsis is characteristic of smooth muscle. True False

True

Smooth muscles relax when intracellular Ca2+ levels drop but may not cease contractions. True False

True

Smooth muscle is characterized by all of the following EXCEPT ________. A) it appears to lack troponin B) there are more thick filaments than thin filaments C) there are no sarcomeres D) there are non-contractile intermediate filaments that attach to dense bodies within the cell

there are more thick filaments than thin filaments