Exam 3 Practice Questions

Question 1

A thin filament of a smooth muscle is NOT composed of:
a. Actin and troponin
b. Troponin and tropomyosin
c. Actin and tropomyosin
d. Actin, tropomyosin, and troponin

Answer 1

c
- Smooth muscle doesnt have troponin - any answer with this is false

Question 2

Select the false statement(s):
a. Calcium channel blockers can inhibit smooth and skeletal muscle
b. Skeletal muscle fibers and cardiac muscle cells have triads
c. Smooth and cardiac muscle use an extracellular calcium influx to trigger
contraction
d. A and B
e. B and C

Answer 2

d
- A - Smooth muscles are inhibited by calcium channel blockers bc they rely on extracellular calcium influx, not skeletal muscles tho (rely on intracellular calcium from the SR)

Question 3

Select the true statement(s):
a. Fast glycolytic fibers are recruited first
b. Fibers with a lot of myoglobin are usually recruited first
c. The smallest motor units are recruited first
d. A and b
e. B and C

Answer 3

e
- Fast glycolytic recruited LAST
- Lots of myoglobin means lots of oxygen
- Smallest first, last is largest

Question 4

The main difference between cardiac muscle and smooth muscle is that
a. Cardiac muscle is striated, and smooth muscle isn’t
b. Smooth muscle has a sarcomere structure, and cardiac muscle doesn’t
c. Cardiac muscle uses troponin for contraction regulation, while smooth
muscle uses calmodulin
d. A and B
e. A and C

Answer 4

e
- B- cardiac muscle does have sarcomeres -> striations, smooth muscle doesnt
have striations
- Calmodulin instead of troponin for smooth muscle

Question 5

Select the false statement(s):
a. A motor unit consists of a motor neuron and all the fibers that innervate it
b. The largest motor units are associated with small controlled units
c. Skeletal muscle fibers are capable of hyperplasia in adults
d. A and B
e. B and C

Answer 5

e
- Largest controls gross movements (leg movements)
- Smallest control fine precise movement (eye or finger movements)
- C - skeletal muscle fibers go through hypertrophy (increase in number)

Question 6

In skeletal muscle contraction, the role of ATP is to:
a. Provide energy through hydrolysis for after the power stroke
b. Break the cross-bridge between actin and troponin
c. Bind to troponin to expose active sites on actin
d. A and B
e. B and C

Answer 6

a
b. i. Actin and myosin
c. i. ATP binds to myosin causing detachment from actin, breaking cross
bridge

Question 7

Select the false statement(s) about muscle contraction:
a. ATP is required to detach myosin from actin in the cross-bridge cycle
b. Calcium binds to troponin in skeletal muscle to allow contraction
c. In smooth muscle, calcium binds to calmodulin to activate MLCK
d. ATP is not required for cross-bridge cycling in cardiac muscle

Answer 7

d
- Cardiac muscle requires ATP for detachment of myosin from actin,
active transport of Ca2+

Question 8

Select the correct sequence of events during excitation-contraction coupling in
skeletal muscle
a. Calcium release from mitochondria → Action potential → Cross-bridge
formation
b. Action potential → Calcium release from sarcoplasmic reticulum →
Cross-bridge formation
c. Action potential → Troponin binding → Calcium release → Cross-bridge
formation
d. Action potential → Troponin binding → Cross-bridge formation →
Calcium release

Answer 8

b
- A - calcium is released to SR not mitochondria, action potential should come first
- C - calcium must be released before it can bind to troponin
- D - reverses the order

Question 9

Characteristics, Advantages, and Disadvantages of Direct muscle
attachment

Answer 9

C: Muscle attaches directly
to bone when the
epimysium fuses directly
with the periosteum

A: Provides physical
protection to vital organs
in the body cavities

D: Less flexibility

Question 10

Characteristics, Advantages, and Disadvantages of Indirect muscle
attachment

Answer 10

C: Epimysium of skeletal
muscle extends as a
tendon, which THEN
anchors the skeletal
muscle to the
periosteum

A: - More muscles can
attach to one singular
bone
- interrelationship with
the functions of skeletal
muscles
- Protect the muscle
from direct contact with
the bone surface
- Long bones can act as a
lever for movement

D: Tendons can be prone to
strain or rupture if they
take on excessive load

Question 11

T/F - Smooth muscle grows by hypertrophy and hyperplasia

Answer 11

True

Question 12

T/F - Skeletal muscle fibers and cardiac muscle cells both have well-developed
sarcoplasmic reticulum

Answer 12

False - cardiac muscle has poorly developed sarcoplasmic reticulum

Question 13

T/F - The structure of a triad is 2 transverse tubules with a terminal cisterna in the middle

Answer 13

False - structure is 2 terminal cisternae with a t-tubule in the middle

Question 14

T/F - The order of membranes from deep to superficial is endomysium,
perimysium, epimysium

Answer 14

True

Question 15

T/F - Fast-oxidizing fibers have fewer capillaries than fast glycolytic fibers

Answer 15

False - fast oxidative fibers have MORE capillaries than fast glycolytic
fibers

Question 16

T/F - Multiunit smooth muscle and cardiac muscle exhibit functional syncytium

Answer 16

False - Single-unit smooth muscle and cardiac muscle exhibit functional
syncytium

Question 17

T/F - The H zone shortens during skeletal muscle contraction

Answer 17

True

Question 18

T/F - In isometric contraction, there is no change in muscle length

Answer 18

True

Question 19

T/F - The smaller the motor unit, the larger the force generated by a skeletal
muscle

Answer 19

False

Question 20

T/F - Acetylcholinesterase prevents ACh from traveling across the synaptic cleft of the neuromuscular junction and inhibits muscle contractions

Answer 20

True

Question 21

T/F - One motor neuron innervates multiple muscle fibers

Answer 21

True

Question 22

Define muscle fatigue and rigor mortis

Answer 22

a. Muscle fatigue - physiological fatigue, where skeletal muscle fails to
contract even though it is being stimulated, because of not enough ATP

b. Rigor mortis - stiffening of the body after death, actin and myosin are
unable to form their cross-bridge because of a lack of ATP

Question 23

What are some factors that affect the force of skeletal muscle contraction?

Answer 23

a. Number of muscle fibers stimulated - more muscle fibers activated - more
force generated

b. Size of myofibers - larger motor unit - more force generated

c. Frequency of stimulation - more muscle fibers stimulated - more force
generated

Question 24

What are the similarities between cardiac and skeletal muscle

Answer 24

a. Striated

b. Sarcomerse

c. Troponin and tropomyosin - calcium binds to troponin, causing
tropomyosin to move, freeing up the actin binding site

d. Have SR and t-tubules

Question 25

Describe cross-bridge detachment in smooth muscle cells

Answer 25

MLCP unbinds myosin globular heads from the active binding site on actin which detaches the cross-bridge

Question 26

What is the recruitment order of skeletal muscle fibers from first to be recruited to last to be recruited

Answer 26

a. Slow oxidative b. Fast oxidative c. Fast glycolytic

Question 27

What is 1 use of ATP in skeletal muscle contraction?

Answer 27

- Unbinding cross-bridges - ATP causes the detachment of cross bridges (detachment of myosin globular heads from active myosin binding sites on actin) - Start the cycle of muscle contraction all over again - Moving Ca2+ back into the SR - Hydrolyzed the ATPase into ADP and Pi

Question 28

What is a motor unit, and how does the size of a motor unit affect skeletal muscle contraction?

Answer 28

- A motor unit is made of - Motor neuron - Junction (synpatic cleft) - All the skeletal muscle fibers in a skeletal muscle are innervated by the neuron via axon terminals - Size is based on the number of skeletal muscle fibers innervated - A larger motor unit creates more force than a smaller motor unit - Smaller activated, then medium, then large - force builds up

Question 29

Which type of muscle(s) have striations

Answer 29

Skeletal and Cardiac

Question 30

Skeletal muscle cell shape/structure

Answer 30

long, cylindrical fibers with multiple nuclei

Question 31

Smooth muscle cell shape/structure

Answer 31

spindle-shaped fibers with one central nucleus

Question 32

Cardiac muscle cell shape/structure

Answer 32

branching fibers with one central nuclei

Question 33

Skeletal, Smooth, Cardiac contraction speed

Answer 33

Fast, Slow, Intermediate

Question 34

What type of muscle(s) have intercalated discs

Answer 34

Cardiac

Question 35

What happens during the sliding filament mechanism of muscle contraction (what decreases, increases, remains the same in size)?

Answer 35

- H zone and I band decrease in size - H - middle region of A band - not overlapping with thin filaments - I - region of thin filament not overlapping with the A band - A band remains the same - Thick filaments (myosin) - Z discs are pulled toward M line, shortening the muscle - Anchor thin filaments

Question 36

Describe a triad and its function.

Answer 36

- T- tubule (transverse tubule) that runs between 2 terminal cisternae of the sarcoplasmic reticulum - Key role in muscle contraction - enables the rapid release of calcium ions from the sarcoplasmic reticulum when the action potential travels down the T-tubules

Question 37

What types of exercise are best for each of the skeletal muscle fibers?

Answer 37

Slow oxidative - endurance - running, cycling, swimming - Reliance on aerobic respiration Fast oxidative - Moderate intensity - Jogging, rowing - Both aerobic and anaerobic energy are used Fast glycolytic - High intensity, short duration - Sprinting, weightlifting, and explosive movements - Relies on anaerobic energy

Question 38

What are 4 similarities between skeletal muscle and cardiac muscle?

Answer 38

- Strations (alternating thick and thin filaments) - Sarcomeres - Z-discs - Troponin and tropomyosin regulate muscle contraction - T-tubules, sarcoplasmic reticulum for calcium regulation - Skeletal and cardiac muscles undergo hypertrophy, not hyperplasia

Question 39

What is something smooth muscle doesn't have? a. triads b. tropomyosin c. caveolae d. dense bodies

Answer 39

a

Question 40

Which of the following is false about smooth muscle contraction? a. it's involuntary and regulated by the autonomic nervous system b. calcium binds to troponin to initiate contraction in smooth muscle c. maintains contractions for long periods with low energy use d. involves the interaction of actin and myosin filaments

Answer 40

b

Question 41

Excitation-contraction coupling of cardiac muscle is NOT stimulated to contract by: a. pacemaker activity by sinoatrial (SA) node in the right atrium b. chemical such as hormones c. calcium channel blockers d. autonomic nervous system

Answer 41

c

Question 42

what is a triad made of in skeletal muscle? a. one T-tubule and one terminal cisterna b. two T-tubules and one sarcomere c. one sarcolemma and two sarcoplasmic reticulum regions d. one T-tubule and two terminal cisternae

Answer 42

d

Question 43

Which of the following is NOT a subgroups of troponin? a. TnA b. TnT c. TnC d. TnI

Answer 43

a

Question 44

T/F - Only the I band decreases/dissapears when skeletal muscle contracts

Answer 44

False

Question 45

What happens after acetylcholine is released from vesicles? a. it is immediately broken down by acetylcholinesterase in the vesicle b. diffuses across the synaptic cleft, binds to receptors on motor end plate c. enters the T-tubules to trigger calcium release d. travels through the bloodstream to reach muscle fibers

Answer 45

b

Question 46

Which of the following is a function of ATP during muscle contraction? a. breaks down actin b. binds to tropomyosin c. powers the detachment of myosin heads from actin d. releases calcium from the sarcoplasmic reticulum

Answer 46

c

Question 47

During muscle contraction, the A-band of the sarcomere a. increases in size b. stays the same size c. decreases in size d. disappears

Answer 47

b

Question 48

T/F - In smooth muscle contraction, MLCP enables crossbridge detachment

Answer 48

True

Question 49

In smooth contract, the bulbous swellings of autonomic nerve fibers are called __ and they form __ with smooth muscle a. axon terminals; neuromuscular junctions b. varicosities; diffuse junctions c. synaptic knobs; dense bodies d. myelin sheaths; tight junctions

Answer 49

b

Question 50

What is the primary role of the sarcoplasmic reticulum in muscle cells? a. synthesizing proteins b. producing ATP c. storing and releasing calcium ions d. transporting oxygen

Answer 50

c

Question 51

What effect does increased calcium concentration in the cytoplasm have on muscle contraction? a. activates troponin to initiate contraction b. prevents ATP from being produced c. blocks myosin from binding to actin d. leads to muscle relaxation

Answer 51

a

Question 52

T/F - Cardiac muscle contain triads but lack t-tubules

Answer 52

False

Question 53

Which muscle types can generate action potentials on their own without external nerve stimulation? a. skeletal b. smooth c. cardiac d. cardiac and smooth

Answer 53

d

Question 54

In skeletal muscle contraction, calcium ions are released from the a. golgi b. nucleus c. sarcoplasmic reticulum d. calcium channels

Answer 54

c

Question 55

T/F - Smooth muscle contraction is slower than skeletal muscle contraction

Answer 55

True

Question 56

In cardiac muscle, what triggers calcium release from the sarcoplasmic reticulum? a. ATP hydrolysis b. action potential in the sarcolemma c. extracellular calcium influx through T-tubules d. acetylcholine

Answer 56

c

Question 57

What is the key difference between skeletal and cardiac muscle E-C coupling? a. skeletal muscle depends on extracellular calcium b. cardiac muscle requires extracellular calcium influx c. both use mechanical coupling only d. cardiac muscle does not use calcium

Answer 57

b

Question 58

T/F - Smooth muscle lacks sarcomeres, but still uses actin and myosin filaments for contraction

Answer 58

True

Question 59

T/F - Aerobic/endurance exercise leads to a decrease in muscle capillaries, mitochondria, and myoglobin content

Answer 59

Flase

Question 60

In skeletal muscle contraction, calcium binds to ______, causing _____ to move and expose binding sites a. troponin; tropomyosin b. actin; myosin c. tropomyosin; troponin d. actin; troponin

Answer 60

a

Question 61

Which statement describes a difference between single unit and multi unit smooth muscle? a. single-unit smooth muscle lacks gap junctions b. single-unit smooth muscle contains pacemaker cells and contracts as a unit c. multi-unit smooth muscle contracts as a functional syncytium d. ulti-unit smooth muscle uses pacemaker cells to coordinate contraction

Answer 61

b

Question 62

Which of the following is NOT a similarity between single-unit smooth muscle and cardiac muscle? a. both are involuntary and under autonomic control b. both are organized into motor units that contract independently c. both use gap junctions to spread electrical signals d. both contain pacemaker cells that initiate contractions

Answer 62

b

Question 63

T/F - Activation of the autonomic nervous system is the ONLY way smooth muscle can be stimulated to contract

Answer 63

False

Question 64

Which statement compares the role of increased intracellular Ca2+ in skeletal, cardiac, and smooth muscle contraction? a. skeletal/cardiac/smooth - Ca²⁺ binds to myosin to initiate contraction b. smooth/skeletal - Ca²⁺ increases contraction, not in cardiac c. skeletal/cardiac - Ca²⁺ binds to troponin, smooth - it activates calmodulin d. skeletal/cardiac/smooth - Ca²⁺ activates actin directly

Answer 64

c

Question 65

Which of the following correctly describes how calcium channel blockers affect muscle contraction in the body? a. stop all 3 types of muscle contractions by blocking Ca2+ release from SR b. only affect skeletal muscle because it depends solely on extracellular Ca2+ c. increase contraction in cardiac muscle by enhancing calcium entry d. no effect on skeletal, but reduce contraction in smooth and cardiac muscle

Answer 65

d