Chapter 8 Muscular System Test Bank Answers

1.

Endomysium separates individual muscle fibers from each other. 
 
True    False

2.

A motor neuron and the muscle fibers that it controls constitute a motor unit. 
 
True    False

3.

In the initiation of muscle contraction, calcium ions bind to tropomyosin, exposing active sites on actin for cross-bridge formation. 
 
True    False

4.

The enzyme ATPase occurs in the globular portion of myosin molecules. 
 
True    False

5.

Acetylcholine released by a motor neuron crosses the synaptic cleft and reaches the motor end plate by diffusion. 
 
True    False

6.

ATP is necessary for muscle relaxation. 
 
True    False

7.

The minimal strength of stimulation needed to elicit a muscle contraction is called the threshold stimulus. 
 
True    False

8.

Cardiac muscle is located in the walls of blood vessels. 
 
True    False

9.

A sarcomere is best described as ________ 
 

10.

Myofibrils are composed primarily of 
 

11.

A motor unit typically includes 
 

12.

The electrical impulse that triggers a contraction travels deep into a skeletal muscle fiber by means of 
 

13.

Neurotransmitter molecules are stored in vesicles within 
 

14.

The enzyme acetylcholinesterase causes acetylcholine to 
 

15.

Creatine phosphate 
 

16.

Binding sites on the surface of actin allow the formation of cross bridges with molecules of 
 

17.

The amount of oxygen needed to support the conversion of lactic acid to glucose by the liver is called the 
 

18.

An example of a partial but sustained contraction of a whole muscle is 
 

19.

The characteristic reddish brown color of skeletal muscle comes from which substance?  
 

20.

The threshold stimulus is the 
 

21.

Rigor mortis that occurs in skeletal muscles a few hours after death is due to 
 

22.

The increase in the number of motor units activated as a result of more intense stimulation is called 
 

23.

In a recording of a muscle twitch, the delay between the time a stimulus is applied and the time the muscle responds is called the 
 

24.

Activities such as distance swimming and distance running are most likely to stimulate development of 
 

25.

When a muscle undergoes atrophy in response to disuse, 
 

26.

Multiunit smooth muscle 
 

27.

The term "muscle" can refer to 
 

28.

Compared to skeletal muscle, smooth muscle 
 

29.

Functions of muscle include  
 

30.

The moveable end of a muscle is attached at its 
 

31.

The muscle primarily responsible for opposing a particular action is called the 
 

32.

A broad sheet of dense connective tissue that connects muscle to muscle is called a(n) ____________. 
 
________________________________________

33.

During anaerobic respiration, pyruvic acid molecules are converted into molecules of ____________. 
 
________________________________________

34.

Anaerobic muscle fatigue is most likely due to an accumulation of __________.  
 
________________________________________

35.

The time lag between muscle stimulation and the beginning of contraction is called the ________. 
 
________________________________________

36.

The rhythmic, wavelike motion produced by visceral smooth muscle is called __________.  
 
________________________________________

37.

The enlargement of muscle fibers as a result of exercise is called ________. 
 
________________________________________

38.

The two neurotransmitters that affect smooth muscle cells are acetylcholine and __________.  
 
________________________________________

39.

Muscles that assist a prime mover are called ________. 
 
________________________________________

40.

The less movable end of a skeletal muscle attachment is called the 
 

41.

A mass of dense connective tissue that connects a skeletal muscle to a bone is called a 
 

42.

The muscle most responsible for a particular movement is called the prime mover or antagonist. 
 
True    False

43.

An antagonist to the sternocleidomastoid muscle would be  
 

44.

The zygomaticus muscle 
 

45.

The rectus femoris muscle  
 

46.

Layers of dense connective tissue that separate and support individual muscles are called 
 

47.

Bundles of skeletal muscle fibers are called 
 

48.

A skeletal muscle cell is also called a skeletal muscle _____________. 
 

49.

In skeletal muscle, the thick filaments are mainly composed of ___________. 
 

50.

Bundles of actin and myosin filaments form structures called ________. 
 

51.

Skeletal muscle cells appear striated because of these parallel bundles. 
 

52.

A myofibril may be thought of as many of these joined end-to-end. 
 

53.

The thin filament of skeletal muscle cells is composed mostly of  
 

54.

This structure of a skeletal muscle cell extends from Z line to Z line. 
 

55.

These are defined as a set of membranous channels that extend inward from the plasma membrane of the muscle cell and pass all the way through the cell.  
 

56.

Enlarged portions of the sarcoplasmic reticulum are called __________. 
 

57.

Neurons that control effectors are called  
 

58.

The functional connection between a neuron and a muscle cell is called a  
 

59.

The gap that separates a muscle cell membrane from the neuron cell membrane in a neuromuscular junction is called the  
 

60.

Neurons that control effectors are called sensory neurons. 
 
True    False

61.

Neurons communicate with muscle cells by releasing chemicals called ____________. 
 

62.

What does not describe the region known as the motor end plate? 
 

63.

Troponin, tropomyosin and actin are all parts of the thin filament. 
 
True    False

64.

The enzyme that catalyzes the breakdown of acetylcholine is called ________. 
 

65.

The neurotransmitter in skeletal muscle contraction is ___________. 
 

66.

When acetylcholine binds to its receptors in the muscle fiber membrane, the membrane becomes more permeable to 
 

67.

Acetylcholinesterase decomposes the crossbridge linkages of myosin to actin. 
 
True    False

68.

When an increased concentration of calcium ion is in the sarcoplasm,  
 

69.

In skeletal muscle cells, this abundant molecule may be used to transfer energy to ADP to form ATP. 
 

70.

In the absence of oxygen, small amounts of ATP may be generated by this process. 
 

71.

During the anaerobic breakdown of glucose, glucose is broken down into  
 

72.

During the aerobic respiration process, glucose is broken down into  
 

73.

This molecule, only present in muscle cells, is used to temporarily store oxygen for use in aerobic respiration. 
 

74.

Only two ATP molecules are produced by glycolysis. 
 
True    False

75.

After death a condition called rigor mortis develops due to a sarcoplasmic increase in calcium levels along with a decreased level of  
 

76.

Muscle fatigue results from a combination of insufficient calcium and an excess of acetylcholine. 
 
True    False

77.

A single contraction of a muscle fiber in response to a single stimulus is a  
 

78.

The time between the moment of stimulation and the beginning of contraction is called the 
 

79.

When a muscle is stimulated repeatedly so that it cannot completely relax between contractions, _________ occurs. 
 

80.

If frequency of stimulation is increased, the force of contraction will increase. 
 
True    False

81.

A motor neuron and all the muscle cells it stimulates is called a 
 

82.

Recruitment refers to increasing the number of motor units involved in a muscle contraction. 
 
True    False

83.

A response to nervous stimulation that originates repeatedly from the spinal cord and stimulates only a few muscle fibers at a time is  
 

84.

In this type of muscle cell, the sarcoplasmic reticulum is not well developed. 
 

85.

In this type of smooth muscle, muscle fibers are separate and not organized into sheets. 
 

86.

Smooth muscle contraction that occurs in wave-like motions to move contents along the length of tubular organs describes 
 

87.

This type of smooth muscle is found in the walls of hollow organs like the stomach, intestine, and urinary bladder. 
 

88.

Intercalated discs are found in skeletal muscle as well as cardiac muscle. 
 
True    False