1. 1
Excitation–contraction coupling in skeletal muscle involves all of the following events EXCEPT one. Which one is this EXCEPTION?
A ATP hydrolysis
B Binding of Ca++ to calmodulin
C Conformational change in dihydropyridine receptor
D Depolarization of the transverse tubule (T tubule) membrane
E Increased Na+ conductance of sarcolemma

2. 2
A single contraction of skeletal muscle is most likely to be terminated by which of the following actions?
A Closure of the postsynaptic nicotinic acetylcholine receptor
B Removal of acetylcholine from the neuromuscular junction
C Removal of Ca++ from the terminal of the motor neuron
D Removal of sarcoplasmic Ca++
Return of the dihydropyridine receptor to its resting conformation

3. 3
Which of the following statements about smooth muscle contraction is most accurate?
A Ca++ independent
B Does not require an action potential
C Requires more energy compared to skeletal muscle
D Shorter in duration compared to skeletal muscle

4. 4
Which of the following best describes an attribute of visceral smooth muscle not shared by skeletal muscle?
A Contraction is ATP dependent
B Contracts in response to stretch
C Does not contain actin filaments
D High rate of cross-bridge cycling
E Low maximal force of contraction

5. 5
Calmodulin is most closely related, both structurally and functionally, to which of the following proteins?
A G-actin
B Myosin light chain
C Tropomyosin
D Troponin C

6. 6
Similarities between smooth and cardiac muscle include which of the following?
Ability to contract in the absence of an action potential
Dependence of contraction on Ca++ ions
Presence of a T tubule network
Role of myosin kinase in muscle contraction
Striated arrangement of the actin and myosin filaments

7. 7
In a normal, healthy muscle, what occurs as a result of propagation of an action potential to the terminal membrane of a motor neuron?
A Opening of voltage-gated Ca++ channels in the presynaptic membrane
B Depolarization of the T tubule membrane follows
C Always results in muscle contraction
D Increase in intracellular Ca++ concentration in the motor neuron terminal
E All of the above are correct

8. 8
Which of the following decreases in length during the contraction of a skeletal muscle fiber?
A A band of the sarcomere
B I band of the sarcomere
C Thick filaments
D Thin filaments
E Z discs of the sarcomere

9. 9
A cross-sectional view of a skeletal muscle fiber through the H zone would reveal the presence of what?
A Actin and titin
B Actin, but no myosin
C Actin, myosin, and titin
D Myosin and actin
E Myosin, but no actin

10. 10
Tetanic contraction of a skeletal muscle fiber results from a cumulative increase in the intracellular concentration of which of the following?
A ATP
B Ca++
C K+
D Na+
E Troponin

11. 11
Weightlifting can result in a dramatic increase in skeletal muscle mass. This increase in muscle mass is primarily attributable to which of the following?
A Fusion of sarcomeres between adjacent myofibrils
B Hypertrophy of individual muscle fibers
C CIncrease in skeletal muscle blood supply
D Increase in the number of motor neurons
E Increase in the number of neuromuscular junctions

12. 12
The delayed onset and prolonged duration of smooth muscle contraction, as well as the greater force generated by smooth muscle compared with skeletal muscle, are all consequences of which of the following?
A Greater amount of myosin filaments present in smooth muscle
B Higher energy requirement of smooth muscle
C Physical arrangement of actin and myosin filaments
D Slower cycling rate of the smooth muscle myosin cross-bridges
E Slower uptake of Ca++ ions following contraction

13. 13
The delay between the termination of the transient depolarization of the muscle membrane and the onset of muscle contraction observed in both muscles A and B reflects the time necessary for which of the following events to occur?
A ADP to be released from the myosin head
B ATP to be synthesized
C A Ca++ to accumulate in the sarcoplasm
D G-actin to polymerize into F-actin
E Myosin head to complete one cross-bridge cycle

14. 14
The increased muscle strength observed during the Tensilon test is due to an increase in which of the following?
A Amount of acetylcholine (ACh) released from the motor nerves
B Levels of ACh at the muscle end-plates
C Number of ACh receptors on the muscle end-plates
D Synthesis of norepinephrine

15. 15
What is the most likely basis for the symptoms described in myasthenia gravis?
A Autoimmune response
B Botulinum toxicity
C Depletion of voltage-gated Ca++ channels in certain motor neurons
D Development of macro motor units following recovery from poliomyelitis
E Overexertion

16. .
ATP is used directly for each of the following processes EXCEPT one. Which one is this
EXCEPTION?
Accumulation of Ca++ by the sarcoplasmic reticulum
Transport of glucose into muscle cells
Transport of H+ from the parietal cells into the lumen of the stomach
Transport of K+ from the extracellular to intracellular fluid
Transport of Na+ from the intracellular to extracellular fluid 16 16
ATP is used directly for each of the following processes EXCEPT one.
Which one is this
 EXCEPTION?
A Accumulation of Ca++ by the sarcoplasmic reticulum
B Transport of glucose into muscle cells
C Transport of H+ from the parietal cells into the lumen of the stomach
D Transport of K+ from the extracellular to intracellular fluid
E Transport of Na+ from the intracellular to extracellular fluid

17. 17 In disuse atrophy of muscle there is
In disuse atrophy of muscle there is
A Decrease in the number of individual muscle fibers in the left gastrocnemius
B Decrease in blood flow to the muscle caused by constriction from the cast
C Temporary reduction in actin and myosin protein synthesis
D Increase in glycolytic activity in the affected muscle
E Progressive denervation

18. 18
Smooth muscle that exhibits rhythmical contraction in the absence of external stimuli also necessarily exhibits which of the following?
A “Slow” voltage-sensitive Ca++ channels
B Intrinsic pacemaker wave activity
C Higher resting cytosolic Ca++ concentration
D Hyperpolarized membrane potential
E Action potentials with “plateaus”

19. 19
The sensitivity of the smooth muscle contractile apparatus to calcium is known to increase in the steady-state under normal conditions. This increase in calcium sensitivity can be attributed to a decrease in the levels of which of the following substances?
A Actin
B Adenosine Triphosphate (ATP)
C Calcium-calmodulin complex
D Calmodulin
E Myosin light chain phosphatase (MLCP)

20. 20 Neurotransmitter at the neuromuscular junction is broken down by
a ) Cholinesterase
b ) Acetylcholine Synthetase
c ) Phosphodiesterase
d ) Decarboxylase

21. 21 Myasthenia gravis is produced due to
a ) Defective production of acetylcholine
b ) Excessive destruction of acetylcholine
c ) Delayed breakdown of acetylcholine
d ) Destruction of acetylcholine receptors

22. 22 Myasthenia gravis is treated effectively by using
a ) Acetylcholine receptor blocker
b ) Acetylcholinesterase
c ) Acetylcholinesterase inhibitor
d ) L-Dopa precursor of dopamine

23. 23 Compound action potential is produced by a ) A single motor nerve
b ) A group of nerve fiber
c ) A myelinated nerve fiber
d ) An unmyelinated nerve fiber

24. 24 Structural and functional unit of the muscle is a ) Sarcomere
b ) Sarcotubular system
c ) Sarcoplasmic reticulum
d ) Sarcolemma

25. 25 The voluntary muscle in the following is a ) Biceps
b ) Multiunit smooth muscle
c ) Visceral smooth muscle
d ) Cardiac muscle

26. 26 Resting membrane potential in a cardiac muscle is a ) -80 to -90 mV
b ) -70 mV
c ) 70 mV
d ) 80 to 90 mV

27. 27 The following are the properties of skeletal muscle except
a ) Excitability
b ) Autorhythmicity
c ) Conductivity
d ) Contractility

28. 28 Starlings’ law states that
a ) Force of contraction of muscle is directly proportional to initial length of the muscle
b ) Force of contraction is not related to initial length
c ) Force of contraction of muscle is directly proportional to initial length of the muscle
d ) Force of contraction is proportional to initial length within physiological limits

29. 29 In isotonic contraction a ) Length of the muscle increases
b ) Tone of the muscle changes
c ) Tone remains the same
d ) Length remains the same

30. 30 In Isometric contraction a ) Length of the muscle increases
b ) Tone of the muscle changes
c ) Tone remains the same
d ) Length remains the same

31. 31 Lifting a weight of 2 kg from the ground is an example of
a ) Isotonic contraction
b ) Isometric contraction
c ) Clonus
d ) Fatigue

32. 32
The muscle fails to respond to second stimuli of any magnitude if it is in
a ) Isotonic contraction
b ) Isometric contraction
c ) Relative Refractory period
d ) Absolute Refractory period

33. 33
The muscle responds to second stimuli of a greater magnitude if it is in
a ) Isotonic contraction
b ) Isometric contraction
c ) Relative Refractory period
d ) Absolute Refractory period

34. 34 Pushing the wall is an example of a ) Isotonic contraction
b ) Isometric contraction
c ) Relative Refractory period
d ) Absolute Refractory period