Ch. 10 Assignment & Quiz

Question 1

Which of the following is not a characteristic of a muscle cell?

plasticity
contractility
conductivity
extensibility
excitability

Answer 1

plasticity

Question 2

Which of the following is not a property that all muscle cells must have to carry out their function?

extensibility
elasticity
audtorhythmicity
contractility
conductivity

Answer 2

autorhythmicity

Question 3

Muscle cells respond to stimuli because they are __________.

excitable
durable
immortal
precursors

Answer 3

excitable

Question 4

Which of the following individuals would have more mitochondria in his skeletal muscle?

a 50-yr-old sedentary computer programmer
a 22-yr-old football player
a long-term hospice patient
a model on a reduced-calorie diet
a newborn

Answer 4

a 22-yr-old football player

Question 5

The __________ of skeletal muscle play the same role as dense bodies in smooth muscle.

Answer 5

Z discs

Question 6

Which of the following muscle proteins is not intracellular?

actin
myosin
collagen
troponin
dystrophin

Answer 6

collagen

Question 7

Parts of the sarcoplasmic reticulum called terminal __________ lie on each side of a T tubule.

Answer 7

cisternae

Question 8

Thick myofilaments consist mainly of the protein __________.

Answer 8

myosin

Question 9

Which muscle(s) can contract without the need for nervous stimulation?

skeletal muscle
smooth muscle
cardiac muscle
smooth and cardiac muscle
skeletal, smooth, and cardiac muscle

Answer 9

smooth and cardiac muscle

Question 10

Which of the following has the largest mitochondria?

slow oxidative fibers
fast glycolytic fibers
cardiac muscle
smooth muscle
intermediate fibers

Answer 10

cardiac muscle

Question 11

Cardiac muscle has very little capacity for regeneration because it lacks __________.

satellite cells
endomysium
sarcomeres
dense bodies
somatic nerve fibers

Answer 11

satellite cells

Question 12

Skeletal muscle fibers develop by the fusion of __________, which are embryonic cells.

Answer 12

myoblasts

Question 13

Most skeletal muscle tissue arises from embryonic __________.

ectoderm
endoderm
mesoderm

Answer 13

mesoderm

Question 14

Weakness in the elderly is due in part to changes in the muscular system but also due to __________.

fewer motor neurons in the spinal cord
increased neuronal production of acetylcholine
more muscle fibers in a motor unit
fewer motor units recruited for a specific activity

Answer 14

fewer motor neurons in the spinal cord

Question 15

Increasing muscle strength late in life is __________.

possible with as little as 40 minutes of exercise per week
possible with two or three hours of exercise per week
not possible due to fibrous tissue replacing muscle

Answer 15

possible with as little as 40 minutes of exercise per week

Question 16

Dystrophin is the protein that is defective in muscular dystrophy. Where is it normally found?

Between the thin myofilaments and the sarcolemma of a muscle fiber
As a transmembrane protein of the sarcolemma
In the Z discs of skeletal and cardiac muscle
In the dense bodies of smooth muscle
Bridging the gap between the sarcolemma and axon terminal

Answer 16

Between the thin myofilaments and the sarcolemma of a muscle fiber

Question 17

Which statement best describes the goal of medications used to treat myasthenia gravis?

To increase the number of ACh receptors
To increase the number of ACh receptors
To promote multiple motor unit summation
To inhibit Ca2+ release from the sarcoplasmic reticulum
To inhibit the function of cholinesterase

Answer 17

To inhibit the function of cholinesterase

Question 18

The study of the muscular system is known as __________.

pathophysiology
myology
neurology
kinesiology
biology

Answer 18

myology

Question 19

All muscle types will respond to an electrical stimulus because all muscle cells are _________.

excitable
contractile
isometric
involuntary
striated

Answer 19

excitable

Question 20

The absence or inhibition of acetylcholinesterase at a synapse would lead to __________.

flaccid paralysis
continued muscle contraction
atrophy
muscle wasting
numbness

Answer 20

continued muscle contraction

Question 21

Where in a sarcomere do actin and myosin overlap?

the I band
the M line
the Z disc
the A band
the H band

Answer 21

the A band

Question 22

What is the role of calcium in muscle contraction?

It binds to tropomyosin to expose a binding site for thick myofilaments.

It binds to troponin to expose a myosin binding site.

It stimulates the passage of an electrical signal along the length of the sarcolemma.

It binds to troponin to expose an actin binding site.

It provides energy for contraction.

Answer 22

It binds to troponin to expose a myosin binding site.

Question 23

What is the loss of muscle mass from disuse called?

hypoplasia
tetanus
myasthenia gravis
myopathy
atrophy

Answer 23

atrophy

Question 24

Which of the following is not true of elastic filaments?

They attach to Z discs.
They are composed of titin.
They run through the core of thin myofilaments.
They prevent overstretching of muscle fibers.
They help to stabilize thick myofilaments.

Answer 24

They run through the core of thin myofilaments.

Question 25

Slow oxidative fibers have more __________ and less __________ than fast glycolytic fibers. myoglobin; lactic acid lactic acid; ATP capillaries; mitochondria glycogen; myoglobin ATP; mitochondria

Answer 25

myoglobin; lactic acid

Question 26

What comprises a motor unit? The distance from one Z disc to the next One myofibril of a muscle fiber One nerve fiber and all the muscle fibers innervated by it One thick myofilament and all thin myofilaments with which it forms cross-bridges One neuromuscular junction

Answer 26

One nerve fiber and all the muscle fibers innervated by it

Question 27

At rest, skeletal muscles receive approximately what percentage of blood pumped by the heart? 2% 10% 50% 25% 75%

Answer 27

25%

Question 28

In a sarcomere, thin myofilaments are anchored to a __________ disc.

Answer 28

Z

Question 29

Which protein acts as a calcium receptor in skeletal muscle? dystrophin tropomyosin titin F actin troponin

Answer 29

troponin

Question 30

The enzyme __________ breaks down acetylcholine and removes it from the synaptic cleft.

Answer 30

Acetylcholinesterase

Question 31

To stimulate muscle contraction, acetylcholine is released from the ___________ into the synaptic cleft. postsynaptic membrane folds sarcolemma terminal cistern sarcoplasmic reticulum synaptic vesicles

Answer 31

synaptic vesicles

Question 32

Which of the following structures store calcium ions that trigger skeletal muscle contraction? mitochondria myofibrils sarcoplasmic reticulum synaptic vesicles T tubules

Answer 32

sarcoplasmic reticulum

Question 33

Which of the following contains overlapping thick and thin myofilaments? M line I band A band Z discs H band

Answer 33

A band

Question 34

Which of the following characterizes Duchenne muscular dystrophy? Muscles atrophy due to a loss of fat and scar tissue. There is a defective gene for the protein called dystrophin. There is a defective gene for the protein called duchennase. More females are affected than males. Muscles atrophy due to lack of response to acetylcholine.

Answer 34

There is a defective gene for the protein called dystrophin.

Question 35

Where is dystrophin, the protein that is defective in muscular dystrophy, normally found? In the Z discs of skeletal and cardiac muscle In the dense bodies of smooth muscle Bridging the gap between the sarcolemma and synaptic knob As a transmembrane protein of the sarcolemma Between the outermost myofilaments and the sarcolemma of a muscle fiber

Answer 35

Between the outermost myofilaments and the sarcolemma of a muscle fiber

Question 36

Where would you expect to find numerous gap junctions in muscular tissue? The intercalated discs of cardiac muscle The sarcoplasmic reticulum of skeletal muscle The A bands of skeletal and cardiac muscle The sarcolemma of skeletal muscle Multiunit smooth muscle

Answer 36

The intercalated discs of cardiac muscle

Question 37

Which muscle type depends solely on the sarcoplasmic reticulum as its calcium source? Smooth muscle Skeletal muscle Cardiac muscle Smooth and cardiac muscle Skeletal and smooth muscle

Answer 37

Skeletal muscle