CHAPTER 9: Muscles and Muscle Tissue
1) With muscular dystrophy ________.
A) muscles decrease in size due to loss of fat and connective tissue
B) muscle fibers degenerate and atrophy
C) most forms do not appear to be inherited
D) most cases appear in young females
2) Which muscle cells have the greatest ability to regenerate?
D) no muscle can regenerate
3) Most 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
4) Fatigued muscle cells that recover rapidly are the products of ________.
A) intense exercise of long duration
B) intense exercise of short duration
C) slow exercise of long duration
D) slow exercise of short duration
5) 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
6) Which of the following would be recruited later in muscle stimulation when contractile
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
7) Which of the following is not a usual result of resistance exercise?
A) increase in the efficiency of the respiratory system
B) increase in the efficiency of the circulatory system
C) increase in the number of muscle cells
D) increase in the number of myofibrils within the muscle cells
8) In skeletal muscle contraction, calcium apparently acts to ________.
A) increase the action potential transmitted along the sarcolemma
B) release the inhibition on Z discs
C) remove the blocking action of tropomyosin
D) cause ATP to bind to actin
9) Calcium ions bind to the ________ molecule in skeletal muscle cells.
10) 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
11) An elaborate network of membranes in skeletal muscle cells that functions in calcium storage
is the ________.
A) sarcoplasmic reticulum
C) intermediate filament network
D) myofibrillar network
12) A sarcomere is ________.
A) the nonfunctional unit of skeletal muscle
B) the area between two Z discs
C) the area between two intercalated discs
D) the wavy lines on the cell seen in the microscope
13) Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short
period called the ________ period during which the events of excitation -contraction coupling
14) 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
15) After nervous stimulation of the muscle cell has ceased, the calcium ________.
A) is destroyed by cholinesterase
B) is chemically bound to the filaments
C) level in the cytoplasm drops
D) is actively pumped into the extracellular fluid for storage until the next contraction
16) The major function of the sarcoplasmic reticulum in muscle contraction is to ________.
A) make and store phosphocreatine
B) synthesize actin and myosin myofilaments
C) provide a source of myosin for the contraction process
D) regulate intracellular calcium concentration
17) The striations of a skeletal muscle cell are produced, for the most part, by ________.
A) a difference in the thickness of the sarcolemma
B) the arrangement of myofilaments
C) the sarcoplasmic reticulum
D) the T tubules
18) Which of the following are composed of myosin?
A) thick filaments
B) thin filaments
C) all myofilaments
D) Z discs
19) During muscle contraction, myosin cross bridges attach to which active sites?
A) myosin filaments
B) actin filaments
C) Z discs
D) thick filaments
20) Which of the following surrounds the individual muscle cell?
21) Smooth muscles that act like skeletal muscles but are controlled by autonomic nerves and
hormones are ________.
A) single-unit muscles
B) multiunit muscles
C) red muscles
D) white muscles
22) Rigor mortis occurs because ________.
A) the cells are dead
B) sodium ions leak out of the muscle
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
23) Which of the following does not act as a stimulus to initiate a muscle contraction?
A) hormonal activity
C) a change in the pH of a muscle
D) a change of temperature
24) The term aponeurosis refers to ________.
A) the bands of myofibrils
B) a sheetlike indirect attachment to a skeletal element
C) the rough endoplasmic reticulum
D) the tropomyosin-troponin complex
25) The oxygen-binding protein found in muscle cells is ________.
26) The contractile units of skeletal muscles are ________.
C) T tubules
27) The site of calcium regulation in the smooth muscle cell is ________.
28) One functional unit of a skeletal muscle is ________.
A) a sarcomere
B) a myofilament
C) a myofibril
D) the sarcoplasmic reticulum
29) The functional role of the T tubules is to ________.
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
30) The role of calcium ions in muscle contraction is to ________.
A) act as a third messenger
B) reestablish glycogen stores
C) bind to regulatory sites on troponin, changing the configuration
D) initiate the conversion of carbon dioxide to oxygen for storage
31) The warm-up period required of athletes in order to bring their muscles to peak performance
is called ________.
B) wave summation
D) incomplete tetanus
32) The main effect of the warm-up period of athletes, as the muscle contractions increase in
strength, is to ________.
A) increase the myoglobin content
B) convert glycogen to glucose
C) tone the muscles and stabilize the joints for the workout
D) enhance the availability of calcium and the efficiency of enzyme systems
33) During vigorous excercise, 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
34) When a muscle is unable to respond to stimuli temporarily, it is in which of the following
A) relaxation period
B) refractory period
C) latent period
D) fatigue period
35) In an isotonic contraction, the muscle ________.
A) changes in length and moves the ʺloadʺ
B) does not change in length but increases tension
C) never converts pyruvate to lactate
D) rapidly resynthesizes creatine phosphate and ATP
36) The muscle cell membrane is called the ________.
37) Smooth muscle is significantly different from striated muscle in several ways. Which of the
following is true?
A) Smooth muscle has transverse tubules.
B) Smooth muscle is larger and more powerful than striated muscle.
C) The fibers of smooth muscle are arranged quadrangularly.
D) Smooth muscle contracts in a twisting way.
38) 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 regulation differs
D) ATP energizes the sliding process
39) The cells of single-unit visceral muscle ________.
A) contract all at once
B) are chemically coupled to one another by gap junctions
C) exhibit spontaneous action potentials
D) consist of muscle fibers that are structurally independent of each other
40) Which of the following statements is not true concerning developmental aspects of muscle?
A) There is no biological basis for the difference in strength between women and men.
B) Skeletal muscle is derived from mesoderm.
C) Skeletal muscle develops from somites.
D) Most muscle tissues develop from myoblasts.
41) Which of the following is true about smooth muscle contraction?
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.
42) 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 noncontractile intermediate filaments that attach to dense bodies within the cell
43) Muscle tissue has all of the following properties except ________.
44) The giant protein titin maintains the organization of the ________ assisting in muscle
A) A band
B) I band
C) Z disc
D) M line
45) 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.
46) 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
D) the electron transport chain
47) 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
48) The sliding filament model of contraction involves ________.
A) actin and myosin sliding past each other and partially overlap
B) the shortening of thick filaments so that thin filaments slide past
C) actin and myosin shortening but not sliding past each other
D) the Z discs sliding over the myofilaments
49) After nervous stimulation stops, ACh in the synaptic cleft is prevented from continuing
stimulation of contraction by ________.
A) calcium ions returning to the terminal cisternae
B) the tropomyosin blocking the myosin once full contraction is achieved
C) acetylcholinesterase destroying the ACh
D) the action potential stopped going down the overloaded T tubules
50) Which of the following is most accurate?
A) Muscle tension remains relatively constant during isotonic contraction.
B) T-tubles may be sliding during isotonic contraction.
C) The I band lenghtens during isotonic contraction.
D) Myofilaments slide during isometric contractions.
51) The most distinguishing characteristic of muscle tissue is ________.
A) the design of the fibers
B) the sarcoplasmic reticulum
C) the diversity of activity of muscle tissue
D) the ability to transform chemical energy into mechanical energy
52) Three discrete types of muscle fibers are identified on the basis of their size, speed, and
endurance. Which of the following athletic endeavors best represents the use of red fibers?
A) a sprint by an Olympic runner
B) a long, relaxing swim
C) playing baseball or basketball
D) mountain climbing
53) Of the following muscle types, which has only one nucleus, no sarcomeres, and rare gap
A) visceral smooth muscle
B) multiunit smooth muscle
C) cardiac muscle
D) skeletal muscle
54) 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 since the muscle has a maximum range of
D) ATP consumption would increase since the sarcomere is ʺtryingʺ to contract
55) An individual has just ingested a chemical that binds irreversibly to the ACh receptors in the
sarcolemma. By itself it does not alter membrane potential, yet prevents normal
neurotransmitter binding. Ignoring the effects on any other system, the consequence to skeletal
muscle would be ________.
A) irreversible contraction as soon as the first nervous stimulation reached the sarcolemma
B) no contraction at all by nervous mechanisms
C) contraction if stimulated by an external electrode
D) no contraction at all by nervous mechanisms, but contraction if stimulated by an external
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