Deck 8: Muscular System

Question 1

ATP is necessary for muscle relaxation.

Answer 1

True

Question 2

A motor unit typically includes

A) muscle fibers only.
B) motor neurons only.
C) several motor neurons and one muscle fiber.
D) one motor neuron and several muscle fibers.
E) several motor neurons and several muscle fibers.

Answer 2

D

Question 3

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

A) sarcoplasmic reticulum.
B) transverse tubules.
C) mitochondria.
D) motor end plates.
E) gap junctions.

Answer 3

B

Question 4

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

Question 5

Neurotransmitter molecules are stored in vesicles within

A) myofibrils.
B) motor units.
C) motor end plates.
D) motor neuron endings.
E) sarcomeres.

Question 6

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

Question 7

Myofibrils are composed primarily of

A) actin and myosin.
B) ATP and ADP.
C) troponin and tropomyosin.
D) fascia and tendons.
E) perimysium and endomysium.

Question 8

The threshold stimulus is the

A) minimum strength of stimulus required to cause muscle fiber contraction to occur.
B) maximal amount of force a muscle can exert.
C) amount of oxygen a muscle needs for repeated contractions.
D) minimal amount of force a muscle can exert.
E) maximal amount of stimulation a muscle can withstand.

Question 9

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

A) eye blinking.
B) tetanic contraction of a muscle fiber.
C) a twitch.
D) muscle tone.
E) fatigue of a motor unit.

Question 10

Creatine phosphate

A) causes the decomposition of ATP.
B) causes the decomposition of ADP.
C) supplies energy for the synthesis of ATP.
D) supplies energy for the breakdown of ATP to ADP.
E) binds to Ach receptors.

Question 11

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

Question 12

A sarcomere is best described as ________

A) a part of the sarcoplasmic reticulum
B) a group of fascicles
C) a group of myofibrils
D) a unit within a myofibril
E) All of the choices are correct.

Question 13

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

Question 14

Cardiac muscle is located in the walls of blood vessels.

Question 15

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

A) ATP.
B) myosin.
C) troponin.
D) tropomyosin.
E) creatine.

Question 16

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

Question 17

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

A) refractory quantity.
B) oxygen debt.
C) anaerobic value.
D) aerobic conversion.
E) lactate debt.

Question 18

Endomysium separates individual muscle fibers from each other.

Question 19

The enzyme acetylcholinesterase causes acetylcholine to

A) bind to actin.
B) be secreted from the motor end plate.
C) decompose.
D) form cross bridges.
E) None of the choices are correct.

Question 20

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

A) actin
B) myosin
C) myoglobin
D) calcium
E) muscle glycogen

Question 21

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

Question 22

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

Question 23

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

Question 24

Multiunit smooth muscle

A) is composed of sheets of muscle cells.
B) tends to display rhythmicity.
C) occurs in the walls of the stomach and intestines.
D) responds to stimulation by neurons and certain hormones.
E) None of the choices apply.

Question 25

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

A) slow fatigable muscle fibers.
B) fast fatigable muscle fibers.
C) slow fatigue-resistant muscle fibers.
D) fast fatigue-resistant muscle fibers.
E) None of the choices are correct.

Question 26

When a muscle undergoes atrophy in response to disuse,

A) there is a reduction in capillary networks.
B) the number of mitochondria decreases.
C) the size of actin and myosin filaments decreases.
D) the muscle gets smaller.
E) All of the answer choices are correct.

Question 27

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

A) refractory period.
B) relaxation period.
C) latent period.
D) contraction period.
E) recovery period.

Question 28

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

Question 29

Functions of muscle include

A) the heartbeat.
B) muscle tone.
C) production of heat.
D) moving body parts.
E) All of the choices are correct.

Question 30

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

A) origin.
B) insertion.
C) tendon.
D) ligament.
E) epimysium.

Question 31

Muscles that assist a prime mover are called ________.

Question 32

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

A) excessive ATP,and decreased membrane permeability to calcium ions.
B) lack of ATP,and increased membrane permeability to calcium ions.
C) persistent stimulation by motor neuron.
D) a decrease in the number of muscle fibers.
E) None of the choices are correct.

Question 33

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

A) latency.
B) recruitment.
C) threshold stimulation.
D) all-or-none response.
E) summation.

Question 34

The term "muscle" can refer to

A) a cell.
B) a tissue.
C) an organ.
D) All of the choices are correct.

Question 35

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

Question 36

The moveable end of a muscle is attached at its

A) origin.
B) fulcrum.
C) insertion.
D) motor end plate.
E) source.

Question 37

Compared to skeletal muscle,smooth muscle

A) contracts more slowly and relaxes more slowly.
B) contracts more slowly and relaxes more rapidly.
C) contracts more rapidly and relaxes more slowly.
D) contracts more rapidly and relaxes more rapidly.
E) is under voluntary control.

Question 38

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

Question 39

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

A) antagonist.
B) prime mover.
C) synergist.
D) agonist.
E) origin.

Question 40

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

Question 41

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

Question 42

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

A) fascia.
B) tendons.
C) cartilage.
D) lamina propria.

Question 43

Neurons that control effectors are called

A) aerobic neurons.
B) sensory neurons.
C) neurotransmitters.
D) motor neurons.
E) motor units.

Question 44

The zygomaticus muscle

A) inserts on the coronoid process of the mandible.
B) elevates the corner of the mouth.
C) brings the head into an upright position.
D) closes the lips.

Question 45

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

A) myosin
B) actin
C) myofibrils
D) sarcoplasm
E) Z lines

Question 46

Enlarged portions of the sarcoplasmic reticulum are called __________.

A) synaptic clefts
B) cisternae
C) H-zones
D) T-tubules
E) motor end plates

Question 47

Neurons that control effectors are called sensory neurons.

Question 48

Neurons communicate with muscle cells by releasing chemicals called ____________.

A) neurotransmitters
B) proteins
C) myosin
D) troponin
E) tropomyosin

Question 49

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

A) myofibril
B) myofilament
C) myosin
D) fiber

Question 50

Skeletal muscle cells appear striated because of these parallel bundles.

A) sarcomeres
B) Z lines
C) myosin
D) myofibrils

Question 51

Bundles of actin and myosin filaments form structures called ________.

A) myofibrils
B) sarcoplasm
C) aponeuroses
D) fascicles
E) transverse tubules

Question 52

An antagonist to the sternocleidomastoid muscle would be

A) on the dorsal side of the body.
B) on the ventral side of the body.
C) inferior to the clavicle.
D) superior to the clavicle and sternum.

Question 53

Bundles of skeletal muscle fibers are called

A) myofibrils.
B) myofilaments.
C) fascicles.
D) myosin.
E) sarcomeres.

Question 54

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.

A) sarcomeres
B) myofibrils
C) transverse tubules
D) cisternae

Question 55

The rectus femoris muscle

A) is a member of the quadriceps femoris group.
B) plantar flexes the foot.
C) extends the thigh at the hip.
D) adducts the thigh.

Question 56

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

A) synaptic cleft.
B) T-tubule.
C) motor end plate.
D) junctional synapse.
E) neuromuscular junction.

Question 57

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

A) sarcolemma
B) sarcomere
C) sarcoplasmic reticulum
D) A band
E) I band

Question 58

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

A) motor end plate.
B) synaptic cleft.
C) synaptic vesicle.
D) junctional plate.
E) neuromuscular junction.

Question 59

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

A) sarcolemmas
B) ribosomes
C) sarcomeres
D) muscle fibers
E) Z lines

Question 60

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

A) origin.
B) insertion.
C) tendon.
D) ligament.
E) epimysium.

Question 61

Acetylcholinesterase decomposes the crossbridge linkages of myosin to actin.

Question 62

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

A) creatine phosphate.
B) pyruvic acid.
C) carbon dioxide.
D) water and ATP.
E) all of the above.

Question 63

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

A) subthreshold stimulus.
B) incomplete recruitment.
C) muscle fatigue.
D) temporal delay.
E) latent period.

Question 64

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

Question 65

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

A) neuromuscular bundle.
B) fascicle.
C) motor unit.
D) myofibril.

Question 66

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

A) actin binding sites are exposed.
B) myosin binding sites are exposed.
C) troponin binding sites are exposed.
D) actin and myosin cannot accomplish contraction.

Question 67

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

A) acetylcholine
B) troponin
C) actin
D) creatine phosphate

Question 68

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

A) potassium.
B) sodium.
C) calcium.
D) acetylcholine.
E) acetylcholinesterase.

Question 69

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

A) myoglobin
B) acetylcholine
C) creatine phosphate
D) lactic acid
E) pyruvic acid

Question 70

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

A) muscle fatigue
B) complete tetanic contraction
C) summation
D) peristalsis

Question 71

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

Question 72

The neurotransmitter in skeletal muscle contraction is ___________.

A) norepinephrine
B) actin
C) acetylcholine
D) tropomyosin

Question 73

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

A) tropomyosin
B) ATPase
C) acetylcholinesterase
D) serotonin

Question 74

Only two ATP molecules are produced by glycolysis.

Question 75

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

A) It is highly folded.
B) Nuclei and mitochondria are abundant.
C) It contains synaptic vesicles.
D) It is part of the muscle fiber.

Question 76

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

A) ATP.
B) ADP.
C) sodium.
D) potassium.
E) myoglobin.

Question 77

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

A) electron transport chain
B) glycolysis
C) citric acid cycle
D) hydrolysis of myoglobin

Question 78

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

Question 79

During the aerobic respiration process,glucose is broken down into

A) creatine phosphate.
B) pyruvic acid.
C) lactic acid.
D) carbon dioxide,water and ATP.

Question 80

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

A) summation.
B) threshold stimulus.
C) twitch.
D) cramp.
E) all-or-none response.