HUMAN ANATOMY AND PHYSIOLOGY 2401

LECTURE TEST # 3

MUSCULAR SYSTEM: SKELETAL MUSCLE, SMOOTH MUSCLE, AND CARDIAC MUSCLE

ANATOMICAL CHARACTERISTICS AND PHYSIOLOGY

DIRECTIONS: For each of the following questions or incomplete statements below select the best or the most appropriate answer in each case.

1. Which one of the following is not a characteristic of skeletal muscle?

1. not striated
2. voluntary
3. controlled by the somatic nervous system
4. all of the above are characteristics of skeletal muscle

2. The connective tissue sheath around an entire muscle is known as:

1. epimysium
2. perimysium
3. endomysium
4. fascia

3. Which one of the following is least related to the others?

1. origin
2. belly
3. proximal
4. less movable

4. Starting with the largest listed below, which one of the following is the third largest in size?

1. fiber
2. sarcomere
3. myofibril
4. I band

5. The I band is made up of entirely of:

1. thick filaments
2. thin filaments
3. fibers
4. myofibrils

6. Which one of the following makes up the thick filaments?

1. tropomyosin
2. actin
3. troponin
4. myosin

7. Which one of the following events listed below occurs thirdly in the contraction of a muscle cell?

1. spread of a stimulatory impulse via the T tubule
2. excitation of a myoneural junction
3. myosin links with actin
4. ATP breaks down

8. The substance that serves essentially as a quickly available energy reserve when muscles are actively contracting is:

1. creatine phosphate
2. glucose
3. ADP
4. Lactic acid

9. The muscle whose contraction opposes a particular movement is knows as a/an:

1. fixator
2. antagonist
3. prime mover
4. synergist

10. Flexion of the elbow is an example of a class _____ lever system.

1. I
2. II
3. III
4. IV

11. A cross section of a myofibril reveals that _____ thin filaments surround each thick filaments.

1. 2
2. 3
3. 4
4. 5
5. 6

12. The type of muscle contraction in which tension develops but no appreciable shortening occurs is________.

1. isometric
2. isotonic
3. isosmotic
4. hypotonic

13. Calcium ions released from lateral sacs bond to:

1. G actin
2. tropomyosin
3. troponin
4. myosin

14. The molecules released by the end of the motor neuron at the myoneural junction is known as:

1. ATP
2. calcium ions
3. acetycholine
4. glucose

15. Myosin can bond with:

1. troponin
2. G actin
3. ADP
4. two of the above are correct

16. Two substances are needed for the contraction of a muscle cell.

1. potassium ion
2. sodium ion
3. glucose
4. oxygen
5. none of the above is correct

17. Elevated respiration after intense physical activity is necessary to provide oxygen for all but which one of the following?

1. production of ATP
2. conversion of lactic acid to glucose
3. resynthesis of creatine
4. the oxidative breakdown of glucose

18. Which one of the following means the same as spatial summation?

1. wave summation
2. tetanus
3. asynchronous motor unit summation
4. multiple motor unit summation

19. Which one of the following is not a characteristic of fast twitch fatigable fibers?

1. well supplied with blood vessels
2. contain much glycogen
3. geared to anaerobic metabolic processes
4. do not contain large amounts of myoglobin

20. Which one of the following is not true of skeletal muscle as compared to smooth muscle? Skeletal fibers can:

1. generate less tension under stretching than smooth muscle
2. shorten far more than smooth muscle
3. contract more rapidly
4. stretch less before exhibiting marked changes in tension

21. Which one of the following is not true of both sooth and skeletal muscle physiology?

1. have thick filaments of myosin
2. thin filaments have actin and tropomyosin
3. use an active transport pump to put the calcium ions back in their storage site so that the fibers can relax
4. have the calcium bond to troponin molecules

22. Which of the following is not a characteristic of visceral muscle?

1. involuntary
2. under control of the autonomic nervous system
3. associated with internal organs
4. straited

23. The connective tissue sheath around a fasciculus is known as:

1. epimysium
2. endomysium
3. perimysium
4. fascia

24. When a muscle is joined to a bone via a cable-like extension of its connective tissue sheath, one calls that attachment_____.

1. direct
2. by an aponeurosis
3. by a tendon
4. by a ligament

25. Which one of the following listed is the smallest in size?

1. fasciculus
2. filament
3. fiber
4. myofibril

26. The length of a band is determined by the length of the:

1. thick filaments
2. thin filaments
3. H zones
4. Z lines

27. Which one of the following is not part of a thin filament?

1. actin
2. tropomyosin
3. myosin
4. troponin

28. T tubules are part of the:

1. sarcolemma
2. lateral sacs
3. sarcoplasmic reticulum
4. sarcomere

29. The energy source that is directly responsible for muscle cell contraction is:

1. protein
2. glucose
3. glycogen
4. ATP

30. Raising the body on its toes is an example of a class______ lever system.

1. I
2. II
3. III
4. IV

31. A group of genetically transmitted diseases characterized by progressive muscular weakness is known as:

1. myasthenia gravis
2. muscular dystrophy
3. muscular atrophy
4. muscular hypertrophy

32. Each thin filament is surrounded by _______ thick filaments.

1. 2
2. 3
3. 5
4. 6
5. none of the above is correct

33. The type of muscle contraction in which there is an appreciable shortening is known as _____.

1. isometric
2. isotonic
3. isomotic
4. hypertonic

34. Myosin heads bond to _______.

1. calcium ions
2. ATP
3. troponin
4. G actin
5. two of the above are correct

35. In a relaxed muscle, calcium ions are stored in the_____.

1. T tubules
2. lateral sacs
3. sarcomere
4. troponins

36. In order for muscle contraction to occur, two substances are necessary: calcium ions and______.

1. DNA
2. creatine phosphate
3. glucose
4. ADP
5. none of the above is correct

37. After periods of intense physical exercise, the body converts lactic acid back to:

1. creatine phosphate
2. glucose
3. ATP
4. creatine

38. A brief response of a muscle to a single stimulus of at least threshold intensity is called a ______.

1. muscle twitch
2. multiple motor unit summation
3. wave summation
4. tetanus

39. Which one of the following does not contribute to muscle fatigue?

1. depletion of ADP
2. buildup of lactic acid
3. changes in pH
4. lack of oxygen

40. The inclusion of more muscle fibers into the contractile state in order to lift a heavy weight is physiologically termed_____?

1. tetanus
2. spatial summation
3. tetanus
4. isometric contraction

41. The greater the load, the _____ the speed of shortening.

1. faster
2. slower
3. there is no relationship between the load on a muscle and the speed of shortening

42. Which one of the following is not true of smooth muscle as compared to skeletal muscle? In smooth muscle:

1. calcium ions are stored in the endoplasmic reticulum
2. calcium ions when released bond to troponin molecules
3. calcium ions can get inside the fiber from the extracellular fluid
4. the thin fibers contain actin and tropomyosin

43. The general function of the skeletal muscular system is:

1. to exert force on bones and produce movement
2. to attach to bone markings
3. to maintain tone in internal organs
4. to give the body a fleshy appearance
5. all of the above

44. When muscles contract, they:

1. move the body or its parts
2. maintain posture
3. produce heat
4. all of the above
5. none of the above

45. Thick myofilaments consist of:

1. actin
2. myosin
3. troponin
4. tropomyosin
5. actin and troponin

46. Which of the following is not a property of a motor unit?

1. consist of a motor neuron and the muscle fibers it innervates
2. axon terminals are called a motor end plates
3. motor units control muscle contractions
4. axon terminals release acetycholine when the axon carries an impulse
5. motor units have two or more axons

47. The function of cholinesterase is to:

1. prevent continuos stimulation by acetycholine
2. bind acetycholine to receptors
3. liberate choline for reuse
4. block receptors and prevent stimulation
5. release acetate for energy

48. Oxygen debt is produced when:

1. muscles are in resting state
2. strenuous exercise has ceased
3. strenuous exercise creates demand for energy
4. metabolism is aerobic
5. oxygen is administered during exercise

49. The events in muscle contraction:

1. impulse depolarizes sarcoplasmic reticulum
2. sarcolemma receives neural stimulus
3. ATPase of myosin is activated and tropomyosin removed from actin
4. calcium ions are released
5. actin and myosin filaments slide over one another

Arrange statements in the correct sequence in which they occur for question 49:
ANSWERS:

A = 2 4 1 3 5
B = 2 1 4 3 5
C = 4 2 1 5 3
D = 3 2 5 1 4
E = 3 5 2 1 4

50. The events in muscle relaxation:

1. attachments of actin and myosin break
2. sarcoplasmic reticulum uses ATP to take up calcium
3. actin and myosin slide apart
4. tropomyosin attaches to actin
5. muscle relaxes

Arrange statements in the correct sequence in which they occur for questions 50: ANSWERS:

A = 2 4 1 3 5
B = 2 1 4 3 5
C = 4 2 1 5 3
D = 3 2 5 1 4
E = 3 5 2 1 4

51. A flat sheet of connective tissue that fastens muscle to nearby structures is called a (an):

1. ligament
2. tendon
3. fasciculus
4. myofibril
5. aponeurosis

52. The functional unit of a myofibril is a (an):

1. actin myofilament
2. myosin myofilament
3. sarcolemma
4. sarcomere
5. all of the above

53. The muscle contraction, which of the following shortens?

1. actin
2. myosin
3. sarcomere
4. both a and b
5. both b and c

54. Rigor mortis is due to:

1. lack of energy for contraction
2. lack of energy for relaxation
3. inactivation of enzymes
4. action of bacterial enzymes

55. According to the all-or-none law of muscle contraction:

1. the stimulus to a muscle is of constant intensity
2. when a muscle fiber contracts it contracts maximally
3. all of the calcium in the sarcoplasmic reticulum is released or none is released
4. all subthreshold stimuli combine to cause contraction
5. an increase in the frequency of stimulation increases the force of contraction

56. A motor unit:

1. has the same number of muscle fibers attached to a single axon in all muscles of the body
2. is composed of all the motor neurons and their axons which travel to a given muscle
3. will increase its force of contraction if the rate of stimulation applied to the motor neuron is increased
4. is always stimulated simultaneously with all other motor units in a given muscle

57. At the myoneural junction:

1. acetycholine is released from the muscle cell in response to an action potential
2. curare prevents the release of acetycholine in response to an action potential
3. acetycholine is rapidly broken down by an enzyme present in the end plate membrane
4. the end plate potential results in the inside of the membrane at the end plate becoming positive and the outside negative
5. the nerve action potential is electrically conducted directly to the muscle without any intervening steps.

58. The two ends of a skeletal muscle are usually attached via tendons to:

1. bones
2. mucous membranes
3. fascia
4. other muscles
5. all of these

59. The muscle attachment to the bone of lesser movement is called the muscle’s:

1. insertion
2. origin

60. The force that a muscle generates via its attachment depends on:

1. the number of fibers
2. the thickness of its fibers
3. the fiber’s length
4. only a and b