Deck 6: The Muscular System

Question 1

Which one of the following statements correctly describes activities of muscles?

A) All muscles produce movement.
B) All muscles shorten when they contract.
C) All muscles are under conscious control.
D) All muscles are attached to bones.
E) All muscles are synergistic.

Answer 1

B

Question 2

The following events are associated with muscle contraction. Which one of the following best describes the order in which these events occur, following the initiation of a contraction by a nerve impulse? 1. T tubules transmit electrical impulses throughout the muscle cell.
2) Myosin contacts actin and pulls it toward the center of the sarcomere.
3) Acetylcholine binds to receptors on the muscle.
4) Troponin-tropomyosin complex shifts to expose myosin binding sites.
5) Calcium is released from the sarcoplasmic reticulum.

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

Answer 2

A

Question 3

Once a muscle cell has depleted its small supply of ready-made ATP, what will it use next for energy?

A) fats
B) phospholipids
C) proteins
D) creatine phosphate
E) glycogen

Answer 3

D

Question 4

Plantar fasciitis is an inflammation of the fascia within the sole of the foot, resulting in foot and heel pain. What is a fascia?

A) a bundle of muscle cells that are enclosed in a connective tissue sheath
B) a bundle of protein filaments (thick and thin) located within muscle cells
C) the fibrous connective tissue sheath that surrounds the fascicles of the muscle
D) a connective tissue structure that attaches one muscle to another muscle
E) the area where the actin and myosin filaments overlap within a muscle cell

Question 5

An individual with the condition of myasthenia gravis is faced with an autoimmune disorder in which the body defenses attack acetylcholine receptors on muscle cells. What would be the expected effect on calcium levels near contractile proteins, following the arrival of an electrical impulse at those neuromuscular junctions?

A) a rapid decrease in concentration due to uptake by sarcoplasmic reticulum
B) a rapid increase in concentration due to release by sarcoplasmic reticulum
C) small or no increases in concentration due to weak responses by acetylcholine receptors
D) a large decrease in concentration that occurs slowly
E) a large increase in concentration that occurs slowly

Question 6

Skeletal muscle groups that work together to create the same movement are referred to as

A) involuntary
B) antagonistic
C) synergistic
D) sarcomeres
E) myofibrils

Question 7

Contraction of a skeletal muscle cell is initiated by the

A) release of acetylcholine by a neuron terminating at the neuromuscular junction
B) release of calcium ions by the neuron into the neuromuscular junction
C) electrical current traveling from the neuron directly into the muscle cell
D) hormones delivered by the blood supply to the nearby tissue
E) release of sodium ions by the neuron into the neuromuscular junction

Question 8

All of the following are necessary for contraction to occur EXCEPT which one?

A) Calcium levels must increase in close proximity to the contractile proteins.
B) ATP must be present.
C) Troponin-tropomyosin complex must shift out of the way.
D) Cross-bridges must form between actin and myosin.
E) The troponin and tropomysin must slide relative to each other, shortening the sarcomere.

Question 9

In order for a muscle contraction to occur, cross-bridges must form between which one of the following structures within a muscle cell?

A) the plasma membrane and the sarcoplasmic reticulum
B) troponin and tropomyosin
C) calcium and tropomyosin
D) acetylcholine and muscle cell receptors
E) actin and myosin

Question 10

Which sequence lists the structures from largest, most inclusive, to smallest?

A) muscle-thick filament-fascicle-muscle fiber-myofibril
B) muscle-fascicle-muscle fiber-myofibril-thick filament
C) fascicle-muscle-myofibril-muscle fiber-thick filament
D) muscle fiber-myofibril-muscle-fascicle-thick filament
E) thick filament-fascicle-myofibril-muscle-muscle fiber

Question 11

Cardiac muscle differs from skeletal muscle in that

A) all cardiac muscle is under involuntary control
B) cardiac muscle is capable of relaxation
C) cardiac muscle contracts in response to an electrical or chemical signal
D) cardiac muscle is excitable and can shorten
E) cardiac muscle gets longer rather than shorter when excited

Question 12

When an electrical impulse traveling along a motor neuron arrives at a neuromuscular junction

A) there is an increase in the secretion of acetylcholine at the neuromuscular junction
B) calcium is transported back to the sarcoplasmic reticulum
C) sliding of actin and myosin filaments is inhibited
D) myosin-actin cross-bridges are destroyed
E) a new electrical impulse is generated that returns the message to the original nerve

Question 13

The primary energy source used by muscle cells to generate ATP is

A) steroids
B) glycogen
C) glucose
D) starch
E) fatty acids

Question 14

Which one of the following statements is TRUE regarding the structure of a muscle?

A) The outer surface of a muscle is enclosed by many layers of epidermis.
B) All muscle cells in a muscle have the same origin and insertion.
C) Fascicles of a muscle are surrounded by a thin sheath of hyaline cartilage.
D) Connective tissues associated with the muscle converge to form a ligament at each end of the muscle.
E) Each fascicle consists of two muscle cells.

Question 15

Which one of the following statements correctly describes the origin and insertion of a muscle?

A) The insertion is pulled toward the origin during contraction.
B) The origin is pulled toward the insertion during contraction.
C) The origin of a muscle is generally distal (farther from the body's midline) relative to the insertion.
D) The origin and insertion refers to the growth pattern of a muscle during development.
E) There is always a ligament at the origin of a muscle and a tendon at the insertion.

Question 16

In the lower leg, the gastrocnemius muscle bends the foot away from the knee, as in pointing one's toes. The tibialis anterior muscle flexes the foot toward the knee. These two muscles are

A) synergistic
B) homeostatic
C) mutualistic
D) antagonistic
E) cooperative

Question 17

As part of your fitness training, you do biceps curls lifting two 10-lb weights. The muscle contractions enabling these movements are

A) isometric contractions
B) tetanic contractions
C) isotonic contractions
D) tendon-mediated contractions
E) ligament-mediated contractions

Question 18

Muscle cells produce lactic acid when they have an inadequate supply of

A) protein
B) O₂
C) calcium
D) actin and myosin
E) glycogen

Question 19

Which one of the following is found within a sarcomere?

A) the muscle cell nuclei
B) muscle fibers
C) the actin and myosin filaments
D) fascicles
E) fascia

Question 20

Which one of the following is the most efficient long-term source of ATP for muscle cells?

A) creatine phosphate
B) ready-made ATP in the cell
C) aerobic respiration of glucose
D) fermentation of glucose
E) aerobic respiration of proteins

Question 21

Intercalated discs

A) are characteristic of smooth muscle cells
B) contain gap junctions that allow the signal to spread quickly through cardiac muscle cells
C) support fast-twitch fibers of skeletal muscle
D) stimulate pacemaker cells in cardiac muscle
E) stimulate the contraction of skeletal muscle

Question 22

At the end of the contractile period, energy from the breakdown of ATP is used to

A) transport calcium back into the sarcoplasmic reticulum
B) repair any muscle damaged during contraction
C) digest energy sources to generate new ATP for the next round of contractions
D) produce lactic acid
E) unlink the troponin-tropomyosin complexes

Question 23

The heads of myosin molecules contact the actin filaments when a muscle is relaxed.

Question 24

Which one of the following activities would fast-twitch fibers be most useful for?

A) distance running
B) swimming
C) lifting weights
D) biking
E) cross-country skiing

Question 25

Following electrical stimulation of a muscle cell, calcium functions to

A) stimulate the enzymes that produce ATP
B) bind to the protein troponin
C) leak out of the muscle cell to re-establish the membrane potential
D) break down acetylcholine
E) maintain the relaxed state of the muscle

Question 26

During a marathon, runners use up ATP and glucose early in the race. Which energy source is generally used next for producing more ATP?

A) glycogen
B) starch
C) cellulose
D) steroids
E) phospholipids

Question 27

Muscle cells are located in every organ in the body except the stomach and are essential for any activity that requires movement.

Question 28

Which one of the following is characteristic of an isotonic muscle contraction but not an isometric muscle contraction?

A) generates a force
B) moves an object or part of the skeleton
C) helps an individual maintain an upright position
D) requires energy
E) helps an individual maintain posture

Question 29

Which one of the following is an example of an isometric contraction?

A) person lifting books from the floor
B) tightening of abdominal muscles while sitting
C) kicking a soccer ball
D) swinging a golf club
E) doing abdominal "crunches" (sit-ups)

Question 30

A myogram is a recording of

A) the electrical activity of muscle cells
B) the electrical activity of nerves at neuromuscular junctions
C) the activity of muscle cells
D) blood pressure changes resulting from muscle contraction
E) the movement of myosin filaments

Question 31

In comparing all three major muscle types, which one of the following statements best describes the differences between them?

A) Cardiac muscle can be stimulated only by nerves, whereas smooth and skeletal muscle contract spontaneously.
B) Smooth and skeletal muscles appear striated, due to the arrangement of muscle filaments, whereas cardiac muscles lack these filaments.
C) Only cardiac muscle is under voluntary control.
D) Smooth and cardiac muscle do not fatigue, whereas skeletal does fatigue.
E) Gap junctions are present in skeletal muscles, but not in other types of muscle.

Question 32

In which one of the following would one expect to find motor units made up of only a few muscle cells?

A) arm muscles
B) eye muscles
C) chest muscles
D) thigh muscles
E) lower-leg muscles

Question 33

Muscle contraction accounts for over 75% of the heat generated by the body.

Question 34

In comparing smooth and cardiac muscle, which one of the following best describes the differences between the two muscle types?

A) Smooth muscle is voluntary, whereas cardiac is involuntary.
B) Both lack muscle filaments, but cardiac muscle has sarcomeres.
C) Cardiac muscle requires periods of relaxation, whereas smooth muscle is always in a state of partial contraction.
D) Cardiac muscle filaments are arranged in bundles, whereas smooth muscles lack filament bundles.
E) Cardiac muscle contracts slowly compared to smooth muscle.

Question 35

In skeletal muscle, potassium ions are stored in the sarcoplasmic reticulum.

Question 36

Muscles constitute 60-70% of our body mass.

Question 37

Following intense exercise, the human body attempts to overcome oxygen debt by

A) sweating
B) elevating heart rate
C) producing ATP
D) taking deep breaths
E) inhibiting contractions of smooth muscle

Question 38

T, or transverse, tubes in skeletal muscle function to

A) transport calcium ions throughout muscle cells
B) allow actin and myosin filaments to slide over each other
C) promote the rapid penetration of the electrical impulse deep into the cell
D) help decrease the amount of ATP produced
E) convert glucose to lactic acid, which helps muscles relax

Question 39

Which one of the following is characteristic of cardiac and smooth muscle, but not skeletal muscle?

A) voluntary contraction
B) striated appearance
C) presence of gap junctions
D) presence of actin and myosin in muscle cells
E) contraction is initiated by motor neurons

Question 40

All of the following occur during the latent period of muscle contraction EXCEPT which one?

A) Myofibrils shorten.
B) Calcium is released from the sarcoplasmic reticulum.
C) Muscle cell membrane initiates an electrical impulse, which travels into the muscle cell.
D) Myosin heads bind to actin filaments.
E) Troponin-tropomyosin complex shifts, exposing myosin heads.

Question 41

Fast-twitch fibers contain large amounts of myoglobin and predominate in "red" muscle.

Question 42

According to the sliding filament mechanism, during a muscle contraction, myosin pulls actin filaments toward the center of a sarcomere, causing the entire sarcomere to shorten.

Question 43

Isometric contractions usually result in no movement of the skeleton or objects.

Question 44

Muscle soreness several days after exercise is an indication that some sarcomeres were permanently damaged.

Question 45

The "all-or-none principle" states that in a given muscle, all of the cells are contracting simultaneously or none of them is contracting.

Question 46

A muscle is arranged in bundles of muscle fibers, called ________.

Question 47

Using the figure above, identify the parts of the sarcomere.

A) sarcomere
B) actin filament
C) myosin filament
D) Z-line
14) Label A represents a(n) ________.
15) Label B represents a(n) ________
16) Label C represents a(n) ________.
17) Label D represents a(n) ________.

Question 48

The contractile proteins that are located in myofibrils are called ________ and ________.

Question 49

Following running for a long distance, the muscle soreness that occurs the next day is due to chemicals released to repair damaged muscles.

Question 50

In the absence of ATP, a contracted muscle can't relax.

Question 51

Unlike skeletal muscle, cardiac and smooth muscle do not respond at all to the nervous system, but contract on their own. Differences in the rate of contraction of smooth and cardiac muscle are due to the action of pacemakers in cardiac muscles.

Question 52

Muscles of the hand contain a high percentage of fast-twitch fibers, which allows for actions that are strong and quick.

Question 53

We are unable to exert any conscious control over the contraction of smooth or cardiac muscle. These muscles are referred to as ________ muscle.

Question 54

Since contraction of the hamstrings causes the knee to bend and contraction of the quadriceps causes the knee to extend, these muscles are said to be ________.

Question 55

Using the figure above and labels T through Z below, identify the structures indicated.

A) fascicle
B) muscle fiber
C) tendon
D) whole muscle
26) Structure A is a(n) ________.
27) Structure B is a(n) ________.
28) Structure C is a(n) ________.
29) Structure D is a(n) ________.

Question 56

Tetanus results from a state of maximum muscle relaxation, which is necessary to allow the muscle to rest before the next contraction.

Question 57

Slow-twitch fibers contain many mitochondria and are well supplied with blood vessels, and can make ATP as they need it.

Question 58

The portion of a myofibril from one Z-line to the next is a(n) ________.

Question 59

A complete cycle of contraction and relaxation of muscle cells due to stimulation by a motor neuron is called a muscle ________.

Question 60

The electrical impulse generated by a muscle cell membrane is transmitted to the sarcoplasmic reticulum by ________.

Question 61

The neurotransmitter, ________, has an excitatory effect on skeletal muscle, causing it to contract.

Question 62

To minimize muscle stiffness and soreness, undertake a new exercise activity in ________ for the first few days.

Question 63

In the absence of calcium, myosin cannot contact actin because of the presence of the ________ covering the myosin binding sites on actin.

Question 64

The most common reason for muscle fatigue is the lack of enough ________ to meet the metabolic demands placed on the muscle.

Question 65

During a workout session, you may begin to experience a burning sensation in a muscle group that you are targeting with your choice of exercises. This is most likely due to anaerobic metabolism in that muscle, generating ________.

Question 66

Contraction of skeletal muscle is caused by the release of neurotransmitters from ________ neurons.

Question 67

In order for fast-twitch muscle fibers to produce ATP, a phosphate from the high-energy molecule ________ is transferred to ADP.

Question 68

Activities associated with aerobic training result in an increase in the amount of ________ in the body.

Question 69

The region where a skeletal muscle cell and a motor neuron come into close proximity to one another is the ________.

Question 70

As the rate of stimulation of motor units of a muscle increases, muscle force increases. This process is known as ________.

Question 71

According to the ________ principle, a muscle cell contracts completely when adequately stimulated by a motor neuron.

Question 72

The mechanical force that is generated when a muscle contracts is known as ________.

Question 73

A protein that stores oxygen in slow-twitch muscle fibers is ________.

Question 74

A student, who was late for class, bounded up four flights of steps, ran down the hall, and then arrived in his classroom, huffing and puffing. This student was breathing hard in order to reverse his body's ________.

Question 75

The swinging of a tennis racket is a brief, high-intensity activity that requires the contraction of ________ fibers.

Question 76

The ability to maintain an upright position is due to ________ muscle contractions.

Question 77

The process of activating more motor units when more force must be exerted is called ________.

Question 78

Cells in cardiac muscle that determine the rate of contraction are ________ cells.

Question 79

What is the role of calcium ions during contraction of a skeletal muscle?

Question 80

If your goal was to become an endurance athlete, what type of training should you select, and why, to increase performance?