Deck 11: Muscle

Question 1

Given what you know about the musculature of the respiratory system, what is the most likely explanation for why you can change your breathing rate at any time?

A) the smooth muscles of the respiratory tract can be consciously controlled, unlike like other involuntary systems in the body
B) breathing rate is achieved through skeletal muscles, which are under partial voluntary control
C) in addition to smooth muscles that allow for conscious control, there are likely skeletal muscles involved that can be consciously controlled
D) there are skeletal muscles involved in breathing that display smooth muscle-like autorhythmicity

Answer 1

B

Question 2

The muscle action potential quickly spreads into the muscle fiber as it travels along the _____, which is an extension of the _____.

A) myofibril; sarcoplasm
B) myofibril; sarcoplasmic reticulum
C) transverse tubules; sarcolemma
D) transverse tubules; sarcoplasm

Answer 2

C

Question 3

The storage form of glucose that is present in muscles cells is known as ______.

Answer 3

glycogen

Question 4

Calcium from the extracellular fluid is important for contraction of which type(s) of muscle?

A) cardiac only
B) cardiac and skeletal
C) cardiac and smooth
D) cardiac, skeletal and smooth

Question 5

Larry is stretching out his leg muscles before going for a run. Which property of muscle allows Larry to do this without hurting himself?

A) contractility
B) elasticity
C) electrical excitability
D) extensibility

Question 6

Which type(s) of muscle contraction is regulated by autonomic motor neurons?

A) cardiac only
B) cardiac and skeletal
C) cardiac and smooth
D) cardiac, skeletal and smooth

Question 7

After eating some questionable taco meat, your friend Joshua begins to throw up those risky tacos he ate only a few hours before. Which muscle function best explains why this might have occurred?

A) production of body movement
B) storage and movement of substances within the body
C) thermogenesis
D) stabilization of body position

Question 8

Which type(s) of muscle contraction can be regulated by acetylcholine?

A) cardiac and skeletal
B) cardiac, skeletal and smooth
C) skeletal and smooth
D) skeletal only

Question 9

Which muscle function explains why you get hot during strenuous exercise?

A) production of movement
B) involuntary stabilization
C) thermogenesis
D) moving substances within the body

Question 10

Which property of muscle allows the stretched muscles to go back to their original shape and size?

A) contractility
B) elasticity
C) electrical excitability
D) extensibility

Question 11

Which muscle property best explains the autorhythmicity of the heart?

A) electrical excitability
B) involuntary control
C) extensibility
D) contractility

Question 12

Which muscle property best explains how the heart generates your blood pressure?

A) elasticity
B) involuntary control
C) extensibility
D) contractility

Question 13

Which of the following muscle functions can explain why your head falls down when you begin to fall asleep during class?

A) production of body movement
B) storage and movement of substances within the body
C) thermogenesis
D) stabilization of body position

Question 14

Which of the following is the best explanation for why the statement "I can control my heart rate" is not entirely true?

A) It is not possible to consciously control other factors that affect heart rate, like breathing and physical activity, and so it is also not possible to consciously control heart muscle contractions.
B) It is possible to consciously control other factors that affect heart rate, like breathing and physical activity, but it is not possible to consciously control heart muscle contractions.
C) It is not possible to consciously control other factors that affect heart rate, like breathing and physical activity, but it is also possible to consciously control heart muscle contractions.
D) It is possible to consciously control other factors that affect heart rate, like breathing and physical activity, and it is possible to consciously control heart muscle contractions.

Question 15

Which type(s) of muscle can display(s) autorhythmicity?

A) cardiac only
B) cardiac and skeletal
C) cardiac and smooth
D) cardiac, skeletal and smooth

Question 16

Which type(s) of muscle contraction is regulated by somatic motor neurons?

A) cardiac and skeletal
B) cardiac, skeletal and smooth
C) skeletal and smooth
D) skeletal only

Question 17

Which type(s) of muscle have transverse tubules?

A) cardiac and skeletal
B) cardiac, skeletal and smooth
C) skeletal and smooth
D) skeletal only

Question 18

Sarcomeres are present in which type(s) of muscle?

A) cardiac and skeletal
B) cardiac, skeletal and smooth
C) skeletal and smooth
D) skeletal only

Question 19

Calcium from the sarcoplasmic reticulum is important for contraction of which type(s) of muscle?

A) cardiac and skeletal
B) cardiac, skeletal and smooth
C) skeletal and smooth
D) skeletal only

Question 20

Which type(s) of muscle contraction can be regulated by norepinephrine?

A) cardiac only
B) cardiac and skeletal
C) cardiac and smooth
D) cardiac, skeletal and smooth

Question 21

During a concentric muscle contraction, _______ moves along _______ toward the M line.

A) actin; myosin
B) myosin; actin
C) tropomyosin; actin
D) tropomyosin; troponin

Question 22

During an isotonic muscle contraction, what happens to the H zone?

A) it does not change
B) it gets longer
C) it gets shorter
D) it gets longer and shorter, successively

Question 23

Which of the following are the contractile proteins of muscle?

A) actin and myosin
B) dystrophin and actin
C) myosin and nebulin
D) tropomyosin and troponin

Question 24

Activation of nicotinic acetylcholine receptors on skeletal muscle cells most directly leads to a/an

A) action potential
B) end plate potential
C) autorhythmic potential
D) receptor potential

Question 25

During the depolarizing phase of a skeletal muscle action potential, ______ ions are moving _____ the cell and during the repolarizing phase _____ ions move _____ _____ the cell.

Question 26

Just like a neuronal action potential, a muscle action potential consists of a depolarizing phase caused by opening of voltage-gated sodium channels followed by a repolarizing phase due to opening of voltage-gated potassium channels and closing of voltage-gated sodium channels.

Question 27

Which muscle protein is responsible for attaching the M line to the Z line?

A) myosin
B) actin
C) titin
D) nebulin

Question 28

The A band corresponds to the full length of which component of the sarcomere?

A) thick filament
B) thin filament
C) titin filament
D) tropomyosin

Question 29

After a person or animal dies, the muscles of the body become very flaccid for a short period of time, before rigor mortis sets in. Which of the following is a possible explanation for why this brief state of flaccidity occurs?

A) Muscle cells become overexcited following death.
B) ATP is depleted and therefore there exists no energy for the contraction cycle.
C) Skeletal muscles require stimulation from the nervous system to contract, which ceases upon death.
D) Ca²⁺ leaks out of cells causing myosin to attach to actin.

Question 30

An end plate potential flows in one direction along a skeletal muscle fiber.

Question 31

Which molecule helps to anchor thin filaments to the ends of the sarcomere?

A) dystrophin
B) myomesin
C) nebulin
D) titin

Question 32

A somatic motor neuron releases _____ onto skeletal muscle to cause it to contract.

Question 33

What happens immediately after ATP attaches to myosin?

A) myosin head attaches to actin
B) myosin head detaches from actin
C) myosin head hydrolyzes ATP to ADP
D) myosin head pivots from 90^o angle to 45^o angle

Question 34

Certain pesticides inhibit acetylcholinesterase. What effects would this have on muscle fibers?

A) it would lead to increased muscle contractions
B) it would lead to increased muscle relaxation
C) it would lead to decreased muscle contractions
D) it would not change muscle fiber activity

Question 35

You are a scientist performing an experiment on some isolated skeletal muscle fibers. You observe that when you observe the muscle fibers under a microscope and apply a small amount of calcium, the fibers contract, but then after a short time they relax back to their original length. Which of the following is (are) possible explanation(s) for this observation?

A) The applied Ca²⁺ activates the muscle, but following the refractory period the Ca²⁺ loses its effect and the muscle relaxes.
B) The applied Ca²⁺ activates the muscle, but the muscle soon dephosphorylates its myosin and relaxes.
C) The applied Ca²⁺ at first activates the muscle, but then is pumped into the sarcoplasmic reticulum and is stored.
D) All of the choices are possible.

Question 36

Which molecule's activity is directly regulated by the presence and binding of calcium?

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

Question 37

What happens during the power stroke of the contraction cycle?

A) myosin head attaches to actin
B) myosin head detaches from actin
C) myosin head hydrolyzes ATP to ADP
D) myosin head pivots from 90^o angle to 45^o angle

Question 38

Which of the following are regulatory proteins of muscle?

A) actin and myosin
B) dystrophin and titin
C) myomesin and nebulin
D) tropomyosin and troponin

Question 39

Which molecule blocks the myosin-binding sites by wrapping around the thin filament?

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

Question 40

Which molecule has an ATP-binding site?

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

Question 41

A buildup of which of the following can lead to skeletal muscle fatigue.

A) ADP
B) creatine phosphate
C) ATP
D) oxygen

Question 42

The skeletal muscle action potential is MOST DIRECTLY important for which process?

A) activating the DHP receptor
B) activating the ryanodine receptor
C) promoting cross-bridge formation
D) triggering neurotransmitter release

Question 43

Glycolysis results in the breakdown of glucose into

A) creatine
B) fatty acids
C) lactic acid
D) pyruvic acid

Question 44

Jeff is holding his arm out to support a heavy book. After a while of maintaining the contraction, he is no longer able to exert any muscle force. This is a result of which phenomenon?

A) glycogenolysis
B) muscle fatigue
C) summation
D) aerobic respiration

Question 45

If you had a drug that physically blocked the ryanodine receptor itself, where in the cell would the drug be binding?

A) sarcolemma
B) sarcoplasmic reticulum
C) mitochondrion
D) troponin

Question 46

Curare is a plant based poison which is used by South American indigenous people as a toxin for hunting, the prey once shot by a dart coated with the toxin asphyxiate due to relaxation of skeletal muscles. Curare has also found use as a surgical anesthetic, again for its property of relaxing skeletal muscle. Which of the following is a possible mechanism for how curare could work?

A) curare inhibits acetylcholinesterase
B) curare activates ryanodine receptors
C) curare blocks sarcoplasmic reticulum Ca²⁺ ATPase pumps
D) curare blocks nicotinic acetylcholine receptors

Question 47

Muscle fatigue can be due to inadequate release of acetylcholine by motor neurons onto skeletal muscle fibers.

Question 48

Lactic acid is produced through which process(es)?

A) aerobic respiration
B) anaerobic respiration
C) creatine phosphate reaction
D) All of the choices are correct.

Question 49

Glucose enters skeletal muscle cells via simple diffusion.

Question 50

Which molecule can be used to quickly regenerate ATP by a direct phosphorylation reaction?

A) creatine phosphate
B) glycogen
C) lactic acid
D) pyruvate

Question 51

Hydrogen ions interfere with the ability of the sarcoplasmic reticulum to release calcium. Given this information, what effect do you think a decrease in pH would have on the force of muscle contraction?

A) decreased force of contraction
B) increased force of contraction
C) no effect on force of contraction
D) no contraction

Question 52

Skeletal muscle cells contain enough ATP to maximally contract for several minutes.

Question 53

Muscle contraction begins when calcium levels ______ and ends when they ______.

A) decrease; decrease
B) decrease; increase
C) increase; decrease
D) increase; increase

Question 54

After a skeletal muscle has contracted, which process is most important for lowering Ca²⁺ levels in the cytoplasm?

A) activity of the acetylcholine receptor
B) activity of the Ca²⁺-ATPase pump
C) closing of the Ca²⁺ release channels (ryanodine receptor)
D) closing of the dihydropyridine receptor

Question 55

Which of the following most accurately describes the effect of decreasing Ca²⁺ concentration on sarcomere activity?

A) troponin is deactivated and tropomyosin covers the actin binding site
B) tropomyosin is deactivated and troponin covers the actin binding site
C) myosin no longer hydrolyzes ATP and detaches from actin
D) myosin no longer binds ATP and recocks into an upright position

Question 56

Which process requires sufficient oxygen to occur?

A) aerobic respiration
B) anaerobic glycolysis
C) creatine phosphate reaction
D) aerobic respiration and anaerobic glycolysis

Question 57

Marathon runners often complete their events between 4 and 5 hours. Throughout the majority of this endurance event, which process is producing ATP?

A) anaerobic respiration
B) aerobic respiration
C) glycolysis fermentation
D) creatine phosphate reaction

Question 58

Which of the following best describes the activity of the ryanodine receptor?

A) nociceptor
B) mechanoreceptor
C) thermoreceptor
D) chemoreceptor

Question 59

When you begin to contract skeletal muscles, which is the first source used to replenish lost ATP?

A) glucose
B) glycogen
C) creatine-phosphate
D) fatty acids and ketone bodies

Question 60

Glucose can be made in skeletal muscle cells through the breakdown of ______.

Question 61

Which of the following would increase the tension produced by a skeletal muscle contraction?

A) increased recruitment of motor units
B) increased frequency of muscle action potentials
C) recruitment of more fast glycolytic muscle fibers
D) All of the choices are correct.

Question 62

When you bend your arm at the elbow, the movement is known as

A) agonism
B) extension
C) flexion
D) pronation

Question 63

Which of the following defines a motor unit?

A) a single motor neuron and all of the muscle fibers it innervates
B) a single muscle fiber and all of the motor neurons that innervate it
C) all of the motor neurons and muscle fibers necessary to produce a single movement
D) a group of motor neurons and muscle fibers that activate together

Question 64

The force a motor unit exerts depends on the rate at which the somatic motor neuron discharges action potentials because calcium is released from the sarcoplasmic reticulum faster than it is pumped back by the Ca²⁺-ATPase pump.

Question 65

Which type(s) of muscle fibers is/are most fatigue resistant?

A) fast glycolytic
B) slow oxidative
C) fast oxidative glycolytic
D) All of the choices are equally fatigue resistant.

Question 66

Which event does NOT occur during the relaxation period?

A) calcium is pumped by Ca²⁺-ATPase
B) myosin-binding sites are covered by tropomyosin
C) actin filaments extend back to their resting position
D) calcium levels are rising in the sarcoplasm

Question 67

Concentric and eccentric are types of ______ contractions.

A) isotonic
B) isometric
C) elastic
D) None of the choices is correct.

Question 68

Competitive weight lifters often try to exceed their own limits of performance by lifting heavier and heavier weights. Dwight is attempting to set his new personal record on the bench press and as he lowers the bar to his chest, he pushes it back up about halfway and begins to struggle. His spotter waits for two seconds while Dwight continues to work by himself, and suddenly the bar begins to move upwards again until it is fully extended, without the intervention of the spotter. Describe the types of muscle contractions that occurred while Dwight was struggling and while he followed through, respectively.

A) isometric, eccentric isotonic
B) isotonic, concentric isometric
C) eccentric, concentric isotonic
D) iosmetric, concentric isotonic

Question 69

You are holding a small textbook in your hand, and you begin to flex your elbow to raise the book. You stop with your elbow flexed at about 90 degrees, and the book held out in front of you. What is occurring in your biceps muscle at this time?

A) your biceps is in a state of unfused tetanus
B) your biceps is latched
C) Ca²⁺ is elevated in biceps muscle fibers
D) both your biceps is in a state of unfused tetanus AND Ca²⁺ is elevated in biceps muscle fibers
E) both your biceps is latched AND Ca²⁺ is elevated in biceps muscle fibers

Question 70

The muscle action potential travels down the T tubule system during the _____ period.

Question 71

A whole muscle is controlled by activation of a single motor unit.

Question 72

Imagine you want to produce a finely controlled movement (like picking up a wine glass by the stem). Would it be better to recruit a motor unit with a lower number of muscle fibers, or a motor unit with a higher number of muscle fibers?

A) higher
B) lower
C) either will do equally well

Question 73

A competitive marathon runner will likely have a higher than average number of which type of muscle fiber?

A) fast glycolytic
B) slow oxidative
C) fast oxidative glycolytic
D) equal amounts of all three

Question 74

Although an individual person's distribution of skeletal muscle fiber types is primarily genetically determined, there exists some evidence that fiber types can change in response to exercise to a limited degree (ie. a slow glycolytic fiber can change to a fast oxidative fiber). If such a change were to occur, which of the following proteins MUST change in some manner as the transition from one muscle type to another occurs?

A) actin
B) troponin
C) myosin
D) Ca²⁺-ATPase

Question 75

Which of the following is correct regarding unfused tetanus in a skeletal muscle fiber?

A) the muscle is being stimulated at a high rate, with some time to relax slightly between stimuli
B) the muscle is being stimulated at a high rate, with no time to relax slightly between stimuli
C) the muscle is producing its maximum tension
D) the muscle is fatigued

Question 76

No energy is expended during an isometric contraction because no actual movement is occurring.

Question 77

Jimothy is out cutting firewood with his dad and when they finish they need to carry it back to their campsite. Jimothy wants to impress his dad with how much would he can carry. What would be the most efficient way for him to carry the most wood while using the least amount of energy?

A) loading as many logs as close to his elbows as possible
B) loading as many logs in his hands as possible
C) loading some logs near his elbows and most on his hands
D) loading some logs near his hands and making multiple trips

Question 78

When the body produces movements, ______ function as fulcrums for levers and ______ act as the levers.

Question 79

Why do fast glycolytic skeletal muscle fibers have the greatest cross sectional area?

A) they are used for producing the greatest amount of force
B) they have the biggest thick filaments
C) they have the most sarcoplasmic reticulum
D) they are used for fine control of movement

Question 80

A competitive sprinter will likely have a higher than average number of which type of muscle fiber?

A) fast glycolytic
B) slow oxidative
C) fast oxidative glycolytic
D) equal amounts of all three