Question 1

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

Accepted Answer

A stimulation period is not a phase of a muscle twitch.

Question 2

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

Accepted Answer

The small gap is called a synaptic cleft.The entire region is called a neuromuscular junction.

Question 3

What supplies the energy for muscle contraction? A)actin B)myosin C)tropomyosin D)ATP E)Ca²⁺

Accepted Answer

ATP supplies the energy necessary for muscle contraction.

Question 4

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

Accepted Answer

Rectus means straight and gives information about the direction of the muscle fibers.

Question 5

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.

Accepted Answer

The synaptic vesicles release acetylcholine,a neurotransmitter,into the synaptic cleft.

Question 6

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

Accepted Answer

All the muscle fibers in a motor unit are stimulated at once.They all either contract or do not contract.

Question 7

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 1000 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.

Accepted Answer

The ocular muscles require much finer control than moving the legs.

Question 8

Which of the following does not attach to the sternocleidomastoid muscle?
A)rib
B)clavicle
C)sternum
D)mastoid process
E)skull

Accepted Answer

The sternocleidomastoid does not attach to a rib.

Question 9

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

Accepted Answer

The actin and myosin filaments stay the same length when a muscle contracts.They just slide past each other.

Question 10

What ion is responsible for initiating muscle contraction? A)Mg²⁺ B)Ca²⁺ C)H⁺ D)Cl^- E)Na⁺

Accepted Answer

Calcium ions are released from the sarcoplasmic reticulum to initiate muscle contraction.

Question 11

What does the word sarco mean?
A)large
B)short
C)muscle
D)tubule
E)smooth

Accepted Answer

The word sarco means muscle.

Question 12

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

Accepted Answer

The T system is not found in other types of cells.

Question 13

A muscle fiber is made up of many
A)muscle cells.
B)T tubules.
C)myofibrils.
D)fascicles.
E)bursa.

Accepted Answer

A muscle fiber is made up of many myofibrils divided into sarcomeres.

Question 14

When a muscle contracts,the H zone almost disappears.

Accepted Answer

The H zone is the area in the center of the sarcomere that almost disappears when the muscle contracts.

Question 15

What does troponin bind to and what happens when it binds? A)Ca²⁺,tropomyosin shifts B)tropomyosin,the sarcomere relaxes C)acetylcholine,the sarcome shortens D)ATP,tropomyosin returns to normal position E)T tubules,the sarcomere shortens

Accepted Answer

Troponin binds to Ca²⁺ and this results in a shift of the tropomyosin threads,exposing myosin-binding sites.

Question 16

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

Accepted Answer

Each myosin molecule is shaped like a golf club.

Question 17

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

Accepted Answer

The gluteus maximus which makes up the buttocks is the largest muscle in the body.

Question 18

One motor neuron activates one muscle fiber.

Accepted Answer

One motor neuron can stimulate from a few to several muscle fibers of a muscle because each axon has several branches.

Question 19

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.

Accepted Answer

A sarcomere extends between two dark vertical lines called Z lines.

Question 20

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

Accepted Answer

The adductor longus adducts the thigh,or moves it toward the midline.It also raises the thigh.

Quiz 13: Muscular System

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

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

What supplies the energy for muscle contraction?

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

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

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

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 1000 muscle fibers?

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

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

What ion is responsible for initiating muscle contraction?

What does the word sarco mean?

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 muscle fiber is made up of many

When a muscle contracts,the H zone almost disappears.

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

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

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

One motor neuron activates one muscle fiber.

One sarcomere

Which way does the adductor longus move the thigh?