Anatomy Muscle Tissue

Choose the best answer to each of the following questions.

1) How does muscle tissue contribute to homeostasis?
A) by generating heat that helps maintain body temperature
B) by moving materials through the body
C) by pulling on bones to move the body
D) A and B are correct.
E) A, B and C are correct.

2) The primary function of muscle is
A) conversion of chemical energy into mechanical energy.
B) conversion of chemical energy into radiant energy.
C) conversion of mechanical energy into heat energy.
D) conversion of heat energy into mechanical energy.
E) conversion of heat energy into chemical energy.

3) Skeletal muscle
A) is striated.
B) is under voluntary control.
C) is primarily regulated by hormones from the endocrine system.
D) A and B are correct.
E) A, B and C are correct.

4) Cardiac muscle
A) is found in the walls of blood vessels and in the heart.
B) is largely under voluntary control.
C) is striated.
D) contraction is dependent on stimulation by the nervous system.
E) is unaffected by hormones.

5) Smooth muscle
A) is largely under voluntary control.
B) is located in the coverings of solid organs.
C) is striated.
D) moves blood through the heart
E) is regulated by the autonomic division of the nervous system.

6) Which of the following is a function of muscle tissue?
A) absorbing heat from the environment
B) storage of triglycerides
C) controlling flow of materials out of the stomach and urinary bladder
D) destabilizing body position
E) storing calcium

7) The ability to respond to stimuli by producing action potentials
A) is called electrical excitability.
B) is a property of muscle tissue.
C) is not exhibited by nervous tissue.
D) A and B are correct.
E) A, B and C are correct.

8) The ability of a muscle tissue to stretch without being damaged is called
A) electrical excitability.
B) contractility.
C) extensibility.
D) irritability.
E) elasticity.

9) A muscle fiber (myofiber) is a muscle
A) contractile unit.
B) cell.
C) protein.
D) sarcomere.
E) A and B are correct.

10) Superficial fascia
A) is composed primarily of dense connective tissue.
B) provides a route for lymphatic and blood vessels as well as nerves to
enter muscles. C) is found between the skeletal muscles and the bones.
D) stores most of the body’s proteins.
E) promotes heat loss.

11) Deep fascia
A) is composed of loose (aerolar) connective tissue.
B) is found between the muscles and the skin.
C) holds muscles with similar functions together.
D) limits movement of muscles.
E) blocks the penetration of nerves and blood vessels into muscles.

12) The outermost extension of deep connective tissue that surrounds a muscle is the
A) endomysium.
B) epimysium.
C) perimysium
D) tendon.
E) aponeurosis.

13) A tendon
A) attaches a muscle to a bone.
B) is an extension of the fused endomysium, perimysium and epimysium of a muscle.
C) contains parallel bundles of collagen fibers.
D) A and B are correct.
E) A, B and C are correct.

14) Which of the following is NOT true?
A) Several nerves accompany each artery that penetrates a muscle cell.
B) Muscle tissue is highly vascular.
C) Somatic motor neurons control skeletal muscle contraction.
D) Somatic motor neurons branch; each branch may control a muscle fiber.
E) A muscle fiber uses large amounts of ATP during contraction.

15) A skeletal myofiber
A) has one centrally located nucleus.
B) is derived from embryonic cells called myoblasts.
C) retains mitotic potential even in the adult.
D) A and B are correct.
E) A, B and C are correct.

16) An adult has more muscle mass than a child. How did that increase in muscle mass occur?

A) atrophy
B) dysplasia
C) hyperplasia
D) dystrophy
E) hypertrophy

17) Transverse tubules
A) are actually tiny pockets of plasma membrane that extend into the muscle cell.
B) are filled with interstitial fluid.
C) prevent the spread of an action potential to the interior of a myofiber. D) A and B are correct.
E) A, B and C are correct.

18) The sarcoplasm
A) is the extracellular fluid around a myofiber.
B) is enriched with glycogen.
C) contains hemoglobin to store O2.
D) contains few mitochondria.
E) includes many nuclei.

19) The sarcoplasmic reticulum of muscle tissue
A) stores Ca2+ ions required for muscle contraction.
B) is called rough endoplasmic reticulum in other tissues.
C) is part of the transverse tubule.
D) is a thread of protein running the length of the muscle cell.
E) removes Ca2+ from the sarcoplasm so that an action potential can be generated.

20) Muscular atrophy
A) is in increase in muscle mass due to increased numbers of myofibrils.
B) is an increase in muscle mass due to increased numbers of myofibers.
C) is a decrease in muscle mass due to loss of myofibrils.
D) is the result of overuse of muscles.
E) is always reversible, no matter what the cause.

21) Which of the following accurately describes the filaments of skeletal muscle tissue? A) The thin filaments have twice the diameter and half the numbers of the thick filaments. B) The filaments extend through the entire length of the myofiber. C) Neither thick nor thin filaments are directly involved in muscle contraction. D) Thin filaments are more abundant than thick filaments in the H zone of the A band. E) Thick and thin filaments overlap each other within the A band of the sarcomere.

22) Myofibrils
A) include contractile proteins which stabilize the structure of the sarcomere. B) include the contractile proteins actin and myosin.
C) include regulatory proteins that keep thick and thin filaments in proper alignment. D) include structural proteins that decrease the extensibility and elasticity of the myofiber. E) include structural proteins the turn the contraction process off or on.

23) Thick filaments
A) are composed primarily of myosin.
B) are able to convert mechanical energy into chemical energy. C) are primarily regulatory proteins.
D) are primarily structural proteins.
E) are composed of different types of proteins that appear as beads on a string.

24) Thin filaments
A) are composed of titin.
B) are connected to the M lines.
C) are able to convert chemical energy to mechanical energy.
D) are composed of actin, troponin and tropomyosin.
E) are the proteins that anchor thick filaments to the Z discs.

25) Which of the following does NOT happen during a muscle contraction?
A) The myosin heads bind to actin.
B) The myosin heads pull the thin filaments toward the M line.
C) The sarcomere shortens.
D) The myofiber and the muscle itself shorten.
E) The thick and thin filaments shorten.

26) A contraction cycle
A) cannot begin until Ca2+ has bound to troponin.
B) cannot begin until the myosin-binding sites on actin are exposed.
C) cannot begin until Ca2+ has bound to tropomyosin.
D) A and B are correct.
E) B and C are correct.

27) Place the events of a contraction cycle in the order in which they occur:
1. ATP hydrolysis
2. detachment of myosin head from actin
3. power stroke
4. crossbridge formation
A) 1, 4, 3, 2
B) 1, 4, 2, 3
C) 1. 3, 4, 2
D) 1, 3, 2, 4
E) 1, 2, 3, 4

28) Repetition of the contraction cycle
A) requires the absence of ATP.
B) requires the presence of an adequate number of Ca2+ ions.
C) requires the action of the ATPase found on actin.
D) A and B are correct.
E) A, B and C are correct.

29) How is excitation of the sarcolemma coupled to the contraction of a muscle fiber? A) Excitation continues into the T-tubules causing Ca2+ active transport channels to open, thus removing Ca2+ from the cytoplasm. B) Excitation causes synthesis of more calsequestrin, thus allowing more Ca2+ to be stored in the sarcoplasmic reticulum. C) Excitation continues into the T-tubules causing Ca2+ release channels to open, thus starting a contraction cycle. D) Excitation causes Ca2+ to be released from troponin, thus allowing more cross-bridges to form between myosin and actin. E) Excitation causes a number of intracellular events, which lower Ca2+ levels, thus stimulating a contraction cycle.

30) All of the following is true of rigor mortis EXCEPT:
A) Cellular membranes become leaky after death.
B) Ca2+ from the sarcoplasmic reticulum accumulates in the cytoplasm.
C) Ca2+ binds to troponin allowing crossbridges to form.
D) Myosin ATPase activity allows the contraction cycle to repeat indefinitely.
E) Muscles contract until proteolytic enzymes from the lysosomes digest crossbridges.

31) Under which condition can muscle fibers generate the most tension? A) when fibers are stretched so that there is no overlap between thick and thin filaments B) when fibers have atrophied and there are fewer thin filaments to overlap thick filaments. C) when fibers are compressed so much that the thick and filaments crumple D) when fibers have insufficient ATPase to initiate power strokes. E) when fibers have an overlap of thick and thin filaments that is close to their resting length

32) A neuromuscular junction (NMJ)
A) is the synapse of a motor neuron with a muscle fiber.
B) includes the synaptic end bulbs of the muscle fiber.
C) includes the motor endplates of the motor neuron.
D) uses Na+ as a neurotransmitter.
E) All of the above are correct.

33) Place the events at the neuromuscular junction (NMJ) in the order in which they occur:
1. release of acetylcholine (ACh)
2. activation of ACh receptors on motor endplate
3. termination of ACh activity by acetylcholinesterase (AChE)
4. arrival of an action potential at the synaptic end bulb
5. diffusion of ACh across the synaptic cleft
6. opening of Na+ channels in the motor endplate
7. production of muscle fiber action potential

A) 4, 1, 2, 5, 6, 7, 3
B) 4, 1, 5, 6, 2, 7, 3
C) 4, 1, 5, 2, 7, 6, 3
D) 4, 1, 5, 2, 3, 7, 6
E) 4, 1, 5, 2, 6, 7, 3

34) Which of the following acts on the NMJ to block stimulation of muscle contraction?
A) botulinum toxin
B) curare
C) neostigmine
D) A and B are correct.
E) A, B and C are correct.

35) How do muscle fibers produce ATP?
A) from creatine phosphate
B) through anaerobic cellular respiration
C) through aerobic cellular respiration
D) A and B are correct.
E) A, B and C are correct.

36) Creatine phosphate
A) is produced when ATP levels in a muscle cell are depressed.
B) production requires the activity of creatine kinase.
C) is much less plentiful in the cytoplasm than is ATP.
D) provides enough energy for 15 minutes of muscle activity.
E) provides enough energy to run a 10 Km race.

37) Anaerobic cellular respiration
A) converts glucose to pyruvic acid and ultimately to lactic acid.
B) can produce energy for 30-40 seconds of contractions.
C) requires O2.
D) A and B are correct.
E) A, B and C are correct.

38) Aerobic cellular respiration
A) converts the pyruvate from glycolysis into CO2, H2O, heat and ATP.
B) occurs in the mitochondria.
C) requires O2, which can be obtained from hemoglobin or myoglobin.
D) is required for muscle activities lasting longer than one minute.
E) All of these are correct.

39) Each of the following contributes to muscle fatigue EXCEPT:
A) depressed Ca2+ levels in the sarcoplasm.
B) presence of adequate amounts of O2 in the mitochondria.
C) elevated levels of lactic acid in the sarcoplasm and blood.
D) depletion of glycogen and other nutrients from the sarcoplasm.
E) elevated ADP levels.

40) Oxygen debt (recovery oxygen uptake)
A) is the amount of O2 required by the body to convert glycogen into lactic acid. B) is the amount of O2 required by the body to remove O2 from myoglobin. C) is the amount of O2 required by the body to recuperate from exercise. D) is the amount of O2 required by the body to convert ATP to ADP. E) is the amount of O2 required by the body to convert creatine phosphate to pyruvate.

41) Each of the following is true EXCEPT that:
A) a single muscle fiber is controlled by a single neuromuscular junction. B) a single motor neuron controls a single muscle fiber.
C) the strength of a muscle contraction depends on the number of motor units stimulated. D) the strength of a muscle contraction depends on the size of the motor units stimulated. E) a motor unit consists of a somatic motor neuron and the skeletal muscle fibers it controls.

42) Which of the following is true of a twitch contraction?
A) During a twitch, all fibers in a motor unit respond to an action potential in a motor neuron.
B) During its latent period, Ca2+ binds to troponin.
C) During its contraction period, Ca2+ is actively transported in the sarcoplasmic reticulum.
D) During its relaxation period, an action potential moves across the sarcolemma and T tubules.
E) All of the above are correct.

43) Wave summation in a muscle fiber
A) occurs when additional stimuli arrive before the fiber has relaxed after the initial stimulus. B) usually result in subsequent contractions that are stronger than the 1st. C) may result in muscle fiber tetany.

D) A and B are correct.
E) A, B and C are correct.

44) Motor unit recruitment
A) occurs when the number of motor units involved in muscle contraction decreases. B) contributes to the production of smooth rather than jerky movements. C) promotes muscle fatigue.
D) prevents sustained contraction of a muscle group.
E) inhibits fine adjustments to muscle strength.

45) Muscle tone
A) is maintained by conscious control from the autonomic division of the nervous system. B) blocks muscle contractions not needed for movement of the body. C) is a property of skeletal, but not, smooth muscle tissue. D) results from involuntary contractions of alternating small groups of motor units. E) increases when motor nerves to a muscle group are damaged.

46) Isotonic contractions
A) generate low muscle tension but allow little change in muscle length. B) generate high muscle tension but allow little change in muscle length. C) are used to move objects or to move the body.
D) are important in maintaining posture.
E) are concentric if the length of the muscle increases during the contraction.
47) Slow oxidative muscle fibers
A) are the muscle cells most involved in short-term activity such as sprinting. B) are the largest and most powerful of the skeletal muscle fiber types. C) contract rapidly and generate ATP anaerobically.

D) resist fatigue and contain large amounts of myoglobin.
E) All of the above are correct.

48) Consider the muscles of a catcher for a professional baseball team. The player must be able to squat for one to three minutes at a time, but also must be able to suddenly stand and forcefully throw a ball to any of the three bases of the infield. Which of the following must true of the training regimen for a catcher? A) Exercises that increase the size, strength and glycogen content of fast glycolytic fibers will help the catcher have the strength to throw the ball to the bases. B) Exercises that increase the size, strength and myoglobin content of slow oxidative fibers will help the catcher maintain the squatting position for longer periods of time. C) Exercises that increase the numbers of each type of skeletal muscle fiber are critical to the catcher’s athletic performance. D) A and B are correct.

E) A, B and C are correct.

49) What is the relationship of exercise to skeletal muscle fibers? A) Endurance exercise can transform some FG fibers into FOG fibers.. B) Strength training exercises can induce production of more filaments in FG fibers. C) Exercise does not change the number of skeletal muscle fibers. D) A and B are correct.

E) A, B and C are correct.

50) Cardiac muscle tissue
A) is autorhythmic.
B) contains branched cells that are connected by intercalated discs. C) obtains Ca2+ required for contraction from the sarcoplasmic reticulum and the interstitial fluid. D) maintains contractions for longer periods of time than skeletal muscle tissue. E) All of the above are correct.

51) Smooth muscle tissue
A) may be stimulated to contract by hormones.
B) has briefer contractions than skeletal muscle tissue.
C) uses calmodulin to remove Ca2+ from the cytoplasm.
D) A and C are correct.
E) B and C are correct.

52) All of the following are true of muscle tissue regeneration EXCEPT: A) Skeletal muscle tissue retains its mitotic ability and ability to regenerate throughout life. B) Smooth muscle fibers of the uterus and arterial walls have regenerative capacity. C) Cardiac muscle tissue has limited regenerative capacity.

D) Most body tissues have more regenerative capacity than the muscle tissues. E) Healthy cardiac muscle fibers may undergo hypertrophy to compensate for damaged cells.
53) Which of the following is true of the development of muscle tissue? A) Most muscle tissue develops from ectoderm.
B) 42-44 pairs of somites that will yield skeletal muscle tissue appear by the end of the 5th week. C) The dermatomes of the somites become muscle tissue.
D) Cardiac muscle tissue develops from the sclerotome layer of the somites. E) Smooth muscle tissue develops from the endodermal cells associated with the intestines.

54) Which of the following is NOT true of the effect of aging on muscular tissue? A) Fibrous connective tissue and adipose tissue replace skeletal muscle tissue as age increases. B) Skeletal muscle strength tends to decrease as age increases. C) Exercise has little effect on delaying or reversing age-related loss of skeletal muscle function. D) The ratio of slow oxidative fibers to other skeletal muscle types increases with age. E) The loss of skeletal muscle tissue may be related to decreased physical activity with age.