Deck 9: Muscular System

Question 1

What is the chief function of T tubules?

A) They allow electrical impulses to travel deep into the cell.
B) They store the calcium ions necessary for muscle contraction.
C) They contain myofilaments necessary for muscle contraction.
D) They store glycogen and oxygen.

Answer 1

A

Question 2

What is the delicate connective tissue that covers each muscle fiber?

A) Endomysium
B) Epimysium
C) Perimysium
D) Periosteum

Answer 2

A

Question 3

Which statement correctly describes the sequence of events in muscle contraction?

A) An impulse triggers the release of acetylcholine (ACh),which diffuses across the synaptic cleft to stimulate the sarcolemma to release ATP.The ATP triggers the actin and myosin filaments to shorten,and muscle contraction occurs.
B) An impulse triggers the release of acetylcholinesterase into the synaptic cleft.This causes calcium ions to be pumped into the T tubules.The calcium allows the myosin heads to latch on to the actin filaments and muscle contraction occurs.
C) An impulse triggers the release of acetylcholine (ACh),which diffuses across the synaptic cleft to stimulate the T tubules to release calcium.The calcium binds with troponin on the actin filaments,which permits the myosin heads to latch on and muscle contraction occurs.
D) An impulse triggers the release of acetylcholine (ACh).This stimulates the sarcolemma,which sends an impulse to the actin and myosin filaments.The myosin heads then latch on to the actin filaments,pulling the Z disks closer together,and muscle contraction occurs.

Answer 3

C

Question 4

How do muscles obtain their energy after about 10 minutes of moderate exercise,and what benefit does it have over other methods?

A) Muscles obtain their energy by metabolizing fatty acids; this is beneficial because fatty acids are plentiful.
B) Muscles obtain their energy through anaerobic respiration of glucose; this is beneficial because anaerobic respiration can generate energy quickly.
C) Muscles obtain their energy through aerobic respiration of glucose; this is useful because it produces more ATP than anaerobic respiration.
D) Muscles obtain their energy by breaking down ATP; this is useful because creatine phosphate is plentiful.

Question 5

Most skeletal muscles remain in a state of

A) relaxation.
B) treppe.
C) incomplete tetanus.
D) complete tetanus.

Question 6

What are myofibrils?

A) Long protein bundles that fill the sarcoplasm and store glycogen
B) The membrane surrounding each muscle fiber
C) Tubules that allow electrical impulses to travel into the muscle cell
D) Another name for muscle cells

Question 7

What are the units of contraction in a muscle called?

A) Myofilaments
B) Z lines
C) Sarcomeres
D) Sarcolemmas

Question 8

A skeletal muscle cell is called a ____________________.

Question 9

How does muscle attach to muscle?

A) Muscle fibers of one muscle merge with the fibers of the other muscle.
B) The epimysium extends past the muscle and merges with the epimysium of the other muscle.
C) The epimysium extends past the muscle as a flat sheet of connective tissue that fuses with the covering of the other muscle.
D) Muscle does not attach to muscle; it only attaches to bone.

Question 10

How do the muscles of a sprinter running the 400-yard dash in 50 seconds receive most of their energy?

A) The aerobic respiration of fatty acids
B) The breakdown of creatine phosphate
C) The anaerobic respiration of glucose
D) The aerobic respiration of glucose

Question 11

Which of the following correctly describes skeletal muscle?

A) It is known as voluntary muscle.
B) It consists of short,branching fibers that fit together at intercalated discs.
C) It is found in the digestive tract,blood vessels,and airways.
D) It is called nonstriated because it does not appear striped when examined under a microscope.

Question 12

When extending the forearm

A) the triceps brachii is the prime mover,and the brachialis is the synergist.
B) the triceps brachii is the synergist,and the brachialis is the prime mover.
C) the triceps brachii is the prime mover,and the brachialis is the antagonist.
D) the triceps brachii is the antagonist,and the brachialis is the prime mover.

Question 13

What is an aponeurosis?

A) A strong,fibrous cord that attaches muscle to bone
B) Connective tissue that covers each muscle fiber
C) Connective tissue that surrounds the muscle outside the epimysium
D) A flat,broad tendon that attaches muscle to another muscle

Question 14

Besides ATP,muscle contraction requires

A) sodium.
B) potassium.
C) calcium.
D) tropomyosin and troponin.

Question 15

According to the sliding-filament model of contraction,how does muscle contraction occur?

A) The myosin heads propel the actin myofilaments toward the center of the sarcomere; this pulls the Z disks closer together,which shortens the sarcomere and the entire muscle.
B) The actin heads propel the myosin filaments toward the center of the sarcomere; this pulls the Z disks closer together,which shortens the sarcomere and the entire muscle.
C) The myosin heads propel the actin myofilaments toward the center of the sarcomere.This causes the myofilaments to shorten,which pulls the Z disks closer together to shorten the sarcomere and the entire muscle.
D) Both the actin and myosin myofilaments shorten,which shrinks the sarcomere and pulls the Z disks closer together.As the Z disks move closer together,the muscle contracts.

Question 16

What is the name of the connective tissue that surrounds the muscle as a whole?

A) Endomysium
B) Epimysium
C) Perimysium
D) Periosteum

Question 17

Which factor influences the strength with which a muscle fiber contracts?

A) The amount of acetylcholine released into the synaptic cleft
B) The amount of calcium released
C) The length of the muscle fiber before the contraction begins
D) The size of the muscle fiber

Question 18

If impulses reach a muscle fiber so rapidly that fibers don't have a chance to relax completely before the next impulse arrives,what condition will occur?

A) Twitch
B) Treppe
C) Incomplete tetanus
D) Complete tetanus

Question 19

In the disease myasthenia gravis,the body produces antibodies against receptors for acetylcholine (ACh).As a result,not all ACh can find a receptor.Based on your knowledge of how muscle contraction occurs,what key symptoms would you expect to see and why?

A) Paralysis,because all ACh must be bound to a receptor for contraction to occur
B) Tetany,because the muscle will fire excessively as the ACh attempts to find a receptor
C) Weakness,because not all of the AChs will find a receptor,resulting in poor nerve transmission
D) Muscle spasms,because the ACh remaining in the synaptic cleft will irritate the receiving nerve

Question 20

What are fascicles?

A) Muscle cells
B) Groups of muscle fibers
C) Types of tendons
D) Neurons that innervate muscles

Question 21

Thick myofilaments consist of a protein called ____________________,whereas thin myofilaments consist of a protein called ____________________.

Question 22

A neuron and all the fibers it stimulates are called a ____________________.

Question 23

The minimum voltage needed to cause a muscle fiber to contract is called the ____________________.

Question 24

The plasma membrane that surrounds a muscle fiber is called a ____________________.

Question 25

Anaerobic respiration produces a by-product called ____________________ that leads to muscle ____________________.

Question 26

The epimysium of a muscle sometimes extends past as a flat sheet of connective tissue called an ____________________ that then fuses with the covering of another muscle.

Question 27

A lack of use causes a muscle to shrink,or ____________________.

Question 28

In an ____________________ contraction,the tension in the muscle increases whereas its length remains the same.

Question 29

The connective tissue surrounding the muscle outside the epimysium is called ____________________.

Question 30

In an ____________________ contraction,the muscle changes length to move a load whereas the tension in the muscle remains the same.

Question 31

The end of the muscle that attaches to the more stationary bone is called the ____________________,whereas the end with the more mobile attachment is called the ____________________.

Question 32

The continuous state of partial contraction that allows you to stand and hold your head up is called ____________________.

Question 33

Between the end of a motor nerve and a muscle fiber is a narrow space called a ____________________.