Deck 13: Muscular System

Question 1

Explain the structural differences between the thick and thin myofilaments.

Answer 1

A THICK FILAMENT IS COMPOSED OF SEVERAL HUNDRED MOLECULES OF THE PROTEIN MYOSIN. EACH MYOSIN MOLECULE IS SHAPED LIKE A GOLF CLUB, WITH THE STRAIGHT PORTION OF THE MOLECULE ENDING IN A GLOBULAR HEAD, OR CROSS-BRIDGE. THE CROSS-BRIDGES OCCUR ON EACH SIDE OF A SARCOMERE BUT NOT IN THE MIDDLE. A THIN FILAMENT CONSISTS OF TWO INTERTWINING STRANDS OF THE PROTEIN ACTIN, WITH TWO OTHER PROTEINS, CALLED TROPOMYOSIN AND TROPONIN, ASSOCIATED WITH THE ACTIN.

Question 2

Which of the following is not a term that refers to how muscles work?

A) prime mover
B) synergists
C) antagonist
D) synergism
E) origin

Answer 2

D.

Question 3

What muscle works in a pair with the biceps brachii?

A) the triceps brachii
B) the trapezius
C) the masseter
D) the pectoralis major
E) the sartorius

Answer 3

A.

Question 4

What does the word brevis mean when referring to a muscle?

A) large
B) small
C) huge
D) long
E) short

Question 5

What is the deltoid muscle shaped like?

A) a long thin line
B) a square
C) a triangle
D) a circle
E) a trapezoid

Question 6

What is the name of the muscle that is responsible for blinking and winking?

A) latissimus dorsi
B) trapezius
C) pectoralis major
D) orbicularis oculi
E) extensor digitorum

Question 7

Because the heart beats continuously, cardiac fibers never relax completely.

Question 8

Of the three types of muscle tissue, which has multinucleated fibers?

A) smooth muscle
B) cardiac muscle
C) skeletal muscle
D) both smooth and skeletal muscles
E) both cardiac and smooth muscles

Question 9

From the outside of a muscle coming in, the first thing encountered would be

A) fascia.
B) fascicle.
C) dense connective tissue.
D) muscle fiber.
E) myofibril.

Question 10

Skeletal muscle contractions play a role in returning the venous blood to the heart.

Question 11

Which of the following is not a function of skeletal muscles?

A) pumping of blood throughout the body
B) support
C) movement of bones
D) maintenance of body temperature
E) protection of internal organs

Question 12

What structure attaches a muscle to a bone?

A) ligaments
B) tendons
C) bursae
D) sarcolemma
E) sarcoplasm

Question 13

Of the three types of muscle tissue, which is voluntary?

A) smooth muscle
B) cardiac muscle
C) skeletal muscle
D) both smooth and skeletal
E) both cardiac and skeletal Skeletal muscle is voluntary.

Question 14

Of the three types of muscle tissue, which is not striated?

A) smooth muscle
B) cardiac muscle
C) skeletal muscle
D) skeletal and smooth lack striations
E) cardiac and smooth lack striations

Question 15

Explain the differences between fast-twitch and slow-twitch muscle fibers.

Question 16

What is found within the intercalated disks of cardiac muscle?

A) sarcoplasmic reticulum
B) gap junctions
C) dense connective tissue
D) bone
E) myoglobin

Question 17

The origin of a muscle is on a stationary bone.

Question 18

Muscles can only pull; they cannot push.

Question 19

What do smooth, cardiac, and skeletal muscle all have in common?

A) They are all uninucleated.
B) They are all striated.
C) They are all found in the walls of blood vessels.
D) The cells of these muscles are all called muscle fibers.
E) They all interlock at intercalated disks.

Question 20

List the functions of the skeletal muscles.

Question 21

Why is the innervation ratio in the ocular muscles one motor axon per 23 muscle fibers, whereas in the gastrocnemius muscle, it is one motor axon per 1,000 muscle fibers?

A) There are more nerves in the upper body than in the lower extremities.
B) The ocular muscles require finer control than moving the legs.
C) The innervation ratio has to do with the overall size of the muscle- the bigger the muscle, the fewer the muscle fibers per motor axon.
D) The gastrocnemius muscle contracts much harder than the ocular muscles do.
E) There are fewer muscle fibers in the gastrocnemius muscle than in the ocular muscles.

Question 22

When the nerve signal reaches the axon terminal, what happens next?

A) The muscle contracts.
B) The synaptic vesicles release neurotransmitter.
C) An electrical signal is formed that jumps the synaptic cleft.
D) H⁺ is pumped into the synaptic cleft.
E) Myosin is released from the axon terminal.

Question 23

One sarcomere

A) extends from Z line to Z line.
B) is composed of many myofibrils.
C) contains only actin fibers.
D) is composed of many muscle fibers.
E) surrounds each muscle in the body.

Question 24

Which of the following is not a phase of a single muscle twitch?

A) stimulation period
B) latent period
C) contraction period
D) relaxation period
E) None of these are phases of a muscle twitch.

Question 25

What does the word sarco mean?

A) large
B) short
C) muscle
D) tubule
E) smooth

Question 26

One motor neuron activates one muscle fiber.

Question 27

One motor unit obeys a principle called the all-or-none law.

Question 28

What does troponin bind to, and what happens when it binds?

A) Ca²⁺; tropomyosin shifts
B) tropomyosin; the sarcomere relaxes
C) acetylcholine; the sarcomere shortens
D) ATP; tropomyosin returns to normal position
E) T tubules; the sarcomere shortens

Question 29

Which way does the adductor longus move the thigh?

A) away from the midline
B) toward the midline
C) in a circle
D) in a cone
E) towards the back

Question 30

Which of the following does not attach to the sternocleidomastoid muscle?

A) rib
B) clavicle
C) sternum
D) mastoid process
E) skull

Question 31

A muscle fiber is made up of many

A) muscle cells.
B) T tubules.
C) myofibrils.
D) fascicles.
E) bursa.

Question 32

What ion is responsible for initiating muscle contraction?

A) Mg²⁺
B) Ca²⁺
C) H⁺
D) Cl^-
E) Na⁺

Question 33

When a muscle contracts, the H band almost disappears.

Question 34

What supplies the energy for muscle contraction?

A) actin
B) myosin
C) tropomyosin
D) ATP
E) Ca²⁺

Question 35

Each actin molecule is shaped like a golf club, with a straight portion ending in a globular head.

Question 36

What happens to the actin and myosin filaments when a muscle contracts?

A) Both of them shorten.
B) Both of them lengthen.
C) Both stay the same length.
D) Actin shortens, while myosin lengthens.
E) Myosin shortens, while actin lengthens.

Question 37

Several of the structures in the muscle cell are given special names. For example, the cytoplasm of a muscle fiber is called the sarcoplasm. Which of the following is truly a unique structure to muscle cells not just a renamed one)?

A) cytoplasm
B) nucleus
C) endoplasmic reticulum
D) transverse T) system
E) plasma membrane

Question 38

What is the biggest muscle in terms of mass) in the body?

A) gluteus maximus
B) sartorius
C) stapedius
D) quadriceps femoris
E) latissimus dorsi

Question 39

What information does the word rectus give you about a muscle?

A) the size of the muscle fibers
B) the attachment of the muscle fibers
C) the action of the muscle fibers
D) the shape of the muscle fibers
E) the direction of muscle fibers

Question 40

What is the name of the small gap that separates the axon terminal of a nerve from the sarcolemma?

A) T tubule
B) sliding filament
C) synaptic cleft
D) synaptic vesicle
E) sarcoplasmic reticulum

Question 41

Fibromyalgia is a temporary condition of achy muscles, usually due to overuse.

Question 42

Which disease is an autoimmune disease characterized by weakness that especially affects the muscles of the eyelids, face, neck, and extremities?

A) myalgia
B) muscular dystrophy
C) myasthenia gravis
D) tendinitis
E) bursitis

Question 43

Which of the following is not a source of ATP for muscle contraction?

A) ATP in the blood
B) ATP produced in the cell
C) the creatine phosphate pathway
D) fermentation
E) aerobic respiration

Question 44

What is happening during the latent period of a muscle twitch?

A) The muscle relaxes and returns to its former length.
B) Fresh ATP binds to the myosin, causing it to return to its resting position.
C) ADP and phosphate are released, and the power stroke of the contraction occurs.
D) The myosin-actin cross-bridges are broken and the sarcomere shortens.
E) The neurotransmitter is diffusing across the synaptic cleft, causing an electrical signal in the muscle cell.

Question 45

Which of the following does not occur when a muscle fatigues?

A) Its energy reserves are depleted.
B) Stimulation continues.
C) Tetanus is achieved.
D) Acetylcholine is crossing the synaptic cleft.
E) The muscle relaxes.

Question 46

Jillian is a top-level cross-country runner due to her having predominantly slow-twitch muscle fibers.

Question 47

Which of the following injuries is most likely to happen to the ankle?

A) sprain
B) strain
C) convulsion
D) bursitis
E) muscular dystrophy

Question 48

Leiomyomas are a type of smooth muscle cancer that occurs in the uterine wall.

Question 49

Of the three pathways for supplying ATP to the muscle, which pathways) do slow-twitch fibers prefer?

A) the creatine phosphate pathway
B) fermentation
C) aerobic respiration
D) the creatine phosphate pathway or fermentation
E) the creatine phosphate pathway or aerobic respiration

Question 50

What is the difference between a tic and a spasm?

A) A tic is a spasm that can be controlled voluntarily.
B) A tic is a strong and very painful spasm, especially of the leg and foot.
C) A tic is caused by stretching or tearing of a muscle, while a spasm is just an involuntary contraction.
D) A tic is caused by the inflammation of a tendon, while a spasm is just an involuntary contraction.
E) A tic refers to achy muscles, usually due to overexercise, while a spasm is just an involuntary contraction.

Question 51

Which of the following does not occur when you are very, very cold?

A) More blood flows to the surface of the body.
B) Smooth muscle contracts inside the blood vessels supplying the skin.
C) The arrector pili muscles contract.
D) Shivering occurs.
E) You get goose bumps.

Question 52

Which of the following is not an energy source for muscle contraction?

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

Question 53

What is the name of a sudden and involuntary muscular contraction, often accompanied by pain?

A) bursitis
B) sprain
C) strain
D) tic
E) spasm

Question 54

Why are slow-twitch muscles dark?

A) They have many more myofibrils per motor unit than fast-twitch fibers.
B) They are designed for strength and explosions of energy.
C) They need less blood than fast-twitch fibers.
D) They contain myoglobin.
E) They have fewer mitochondria.

Question 55

Contraction of a muscle requires all the motor units to be undergoing tetanic contraction.

Question 56

In good muscle tone, how many motor units are contracted?

A) none
B) some
C) all
D) 5-10% of the motor units
E) 10-15% of the motor units

Question 57

What happens when the arrector pili muscles contract?

A) Your head nods "yes."
B) Your leg kicks out.
C) The hairs on your skin stand on end.
D) The blood from your skin is rerouted to your core.
E) You tap your finger.

Question 58

Which muscle injury is characterized by a twisting of a joint leading to swelling and injury?

A) sprain
B) strain
C) tendinitis
D) bursitis
E) myalgia

Question 59

Of the three pathways for obtaining ATP for muscle contraction, which one requires oxygen?

A) only the creatine phosphate pathway
B) only fermentation
C) only respiration
D) fermentation and respiration
E) the creatine phosphate pathway and fermentation

Question 60

What is the reservoir for Ca²⁺ in the body?

A) muscles
B) bones
C) liver
D) brain
E) blood

Question 61

If you lock your knees while standing, you may pass out because of the lack of venous return to the heart.

Question 62

Temperature-sensitive neurons in the skin are responsible for initiating shivering.