Deck 6: The Peripheral Nervous System: Afferent Division; Special Senses

Question 1

Fast-glycolytic muscle fibres do not require as much oxygen use as slow-oxidative fibres.

Answer 1

True

Question 2

A skeletal muscle undergoes hypertrophy mainly by producing many more muscle fibres.

Answer 2

False

Question 3

Cross bridges have actin binding sites that are normally covered by troponin and tropomyosin, except during excitation-contraction coupling.

Answer 3

False

Question 4

A single muscle cell is known as a myofibril.

Question 5

Rigor mortis occurs when Ca²⁺ links actin and the myosin globular head together in a rigor complex.

Question 6

Myosin has ATPase activity.

Question 7

The two types of fast twitch fibres are interconvertible depending on the type of conditioning they receive.

Question 8

Foot proteins link the actin molecules together within a thin filament.

Question 9

Thin and thick filaments overlap in the A band.

Question 10

According to the sliding filament mechanism of muscle contraction, the muscle fibres of one motor unit slide in closer together between the muscle fibres of adjacent motor units.

Question 11

The metabolic capability of a muscle fibre can affect the degree of tension it can develop.

Question 12

During the power stroke, all the cross bridges on myosin do not stroke in unison when pulling the actin filaments.

Question 13

Joints serve as fulcrums for muscle action.

Question 14

Oxidative phosphorylation occurs within the mitochondria of muscle cells.

Question 15

The corticospinal system controls fine, discrete, voluntary body movements.

Question 16

The strength and rate of contraction of the heart can be influenced by the autonomic nervous system.

Question 17

Tropomyosin covers the cross-bridge binding sites on the thick filaments when a sarcomere is not contracting.

Question 18

In an isotonic contraction, only 25 percent of the energy consumed is realized as external work, and the remaining 75 percent is converted to heat.

Question 19

The contraction phase of a muscle cell lasts longer than the relaxation phase.

Question 20

The actin filaments in sarcomere contain cross bridges.

Question 21

Skeletal muscles are capable of limited repair after injury.

Question 22

The skeletal muscle shortens during concentric, isotonic contraction.

Question 23

Ligaments attach muscles to bones.

Question 24

Acetylcholinesterase removes ACh from receptors.

Question 25

More tension is developed during twitch summation than during a single twitch because the duration of elevated cytosolic Ca²⁺ concentration increases during summation, thus increasing the availability of cross-bridge binding sites.

Question 26

ATP expenditure is required for both contraction and relaxation of a muscle fibre.

Question 27

According to the sliding filament mechanism of muscle contraction, the thick filaments slide in closer together to shorten the sarcomere.

Question 28

Gradation of muscle contraction can be accomplished by stimulating variable portions of each motor unit.

Question 29

Fast-oxidative muscle fibres have a high concentration of mitochondria.

Question 30

Single-unit smooth muscle and cardiac muscle are both self-excitable.

Question 31

Myosin is considered to be a regulatory protein because it plays an important role in the regulation of muscle contraction.

Question 32

Tetanus occurs when a muscle fibre is stimulated so rapidly that it is not allowed to relax between stimulations, resulting in a smooth, sustained contraction.

Question 33

Increasing the number of recruited motor units in a muscle increases its force or strength of contraction.

Question 34

Muscles that have a fine degree of control have small motor units.

Question 35

The M line is formed by a flattened disc-like cytoskeletal protein that connects the thin filaments of two adjoining sarcomeres.

Question 36

All muscle-lever systems work at a mechanical disadvantage.

Question 37

Single-unit smooth muscle has no innervation.

Question 38

Oxygen debt is the oxygen a skeletal muscle produces or pays off when it carries out glycolysis.

Question 39

Both multiunit and single-unit smooth muscles are under motor control from the autonomic nervous system.

Question 40

During muscle contraction, the A band becomes shorter.

Question 41

All smooth muscle is myogenic.

Question 42

The larger the motor units within a muscle, the more precisely controlled the gradations of contraction.

Question 43

The work performed by a muscle is the force it develops divided by distance.

Question 44

The shorter a muscle fibre is before the onset of a contraction, the greater the force that can be developed upon the subsequent contraction because the thin filaments are already partially slid inward.

Question 45

Slow-oxidative muscle fibres would be found in high density in the leg muscles of Olympic sprinters.

Question 46

Central fatigue of a muscle results directly from the accumulation of lactic acid in the muscle.

Question 47

In order for relaxation to occur, ACh must be removed from the muscle cell's receptors.

Question 48

The functional unit of skeletal muscle is the myofibril.

Question 49

Slow-oxidative muscle fibres have high resistance to fatigue.

Question 50

Skeletal muscle fibres are formed during embryonic development by the fusion of many smaller cells.

Question 51

All skeletal muscles are attached to the skeleton.

Question 52

Anaerobic exercise is endurance-type exercise.

Question 53

The H zone of the sarcomere consists of myosin but does not contain actin.

Question 54

A skeletal muscle produces motion by pulling the origin toward its insertion.

Question 55

A motor unit is a single muscle plus all the motor neurons that innervate it.

Question 56

Summation events result from increasing amounts of cytoplasmic calcium levels.

Question 57

The T tubule ranges transversely to the surface of the muscle cell membrane.

Question 58

Atrophy can develop in a muscle by either denervation or disuse.

Question 59

The lever system at the elbow joint provides a mechanical advantage so that, when the biceps muscle contracts to flex the elbow joint and lift an object in the hand, the force developed in the biceps can be considerably less than the actual load that is moved.

Question 60

Muscle tension does not develop in isometric contractions.

Question 61

With twitch summation, the muscle fibre is stimulated so rapidly that it does not have an opportunity to return to resting potential between stimuli.

Question 62

Which of these statements correctly describes the corticospinal system?

A)It consists of fibres that originate within the primary motor cortex and terminate on motor neurons.
B)It involves the motor regions of the cortex, the cerebellum, the basal nuclei, and the thalamus.
C) It is concerned primarily with regulation of overall body posture.
D) It consists of fibres that originate within the parietal lobe and terminate on the posterior grey horn of the spinal cord.

Question 63

Muscles developing tension while lengthening are performing what type of contractions?

A)concentric
B)eccentric
C) isometric
D) fatiguing

Question 64

Muscle relaxation does not take place until all the ATP is used up.

Question 65

Which of the following areas is the origin of a muscle?

A)the main, thick part of the structure
B)the middle, thin part of the structure
C) the movable end of attachment
D) the stationary end of attachment

Question 66

Which of the following would happen if ATP supplies became very low or were not available in a muscle cell?

A)An increase in tension would develop.
B)Cross bridges would detach from actin.
C) Muscles would relax.
D) ATP would not be required for detachment from actin.

Question 67

Which of the following compounds binds with the calcium that enters the cell during smooth muscle excitation?

A)calmodulin
B)inactive myosin kinase
C) troponin
D) myosin

Question 68

Which of these statements does NOT correctly describe steroids?

A)Steroids can increase muscle mass when used in large amounts.
B)Anabolic steroids and their derivatives are controlled substances in Canada.
C) Addiction to anabolic steroids is possible.
D) In females, anabolic steroids may favour ovulation.

Question 69

How are sarcomeres arranged end to end?

A)as fascicles
B)as myofibrils
C) as bands
D) as perimysia

Question 70

Denervated muscle fibres become progressively smaller and their content of actin and myosin decreases.

Question 71

Which of the following composes thick filaments in skeletal muscle?

A)actin
B)troponin and tropomyosin
C) myosin
D) actin, troponin, and tropomyosin

Question 72

Muscle cells are the only cell types that contain intracellular contractile proteins.

Question 73

What causes the striated appearance of skeletal muscle?

A)regular arrangement of the T tubules running transversely through the muscle fibre
B)presence of the Z lines extending down the middle of the I bands
C) presence of gap junctions
D) regular arrangement of highly organized thick and thin filaments

Question 74

Which of the following are in the I band of the sarcomere?

A)overlapping thin and thick filaments
B)thick filaments only
C) thin filaments only
D) two Z lines

Question 75

What can activate the stretch receptors in the central portion of the muscle spindle?

A)passive stretch of the skin overlying the muscle
B)contraction of the central portions of the muscle fibre
C) gamma motor neuron stimulation
D) an alpha motor neuron

Question 76

Which of the following correctly describes multiunit smooth muscle?

A)It is chemically activated.
B)It is under ANS control.
C) It is found in the walls of the digestive system.
D) It is the most dominant component of smooth muscle.

Question 77

Fatigue is the failure of a muscle fibre to maintain which of the following as a result of previous contractile activity?

A)excitability
B)muscle mass
C) tension
D) sarcomere number

Question 78

Which of these statements correctly describes why you are able to repeatedly contract and relax your muscles of respiration, allowing you to breathe in and breathe out?

A)As soon as all the Ca²⁺ stored in the lateral sacs of the sarcoplasmic reticulum is used up, muscle relaxation occurs.
B)After the muscle cells become excited, acetylcholinesterase maintains the action of acetylcholine.
C) When there is no longer a local action potential in the muscle cell, Ca²⁺ is actively transported back into the lateral sacs of the sarcoplasmic reticulum.
D) ATP is not available soon after the contraction.

Question 79

The heart initiates its own action potentials without any external influence.

Question 80

Which of the following statements is NOT characteristic of cross bridges?

A)They are a component of thin filaments.
B)They are composed of myosin.
C) They have an actin binding site.
D) They have an ATPase binding site.