Topic;Cell+Nerve and muscle physiology
Mcqs Discussion
1) 42 years old patient has diplopia, fatigue, dysphagia, breathing difficulties, ptosis. Ihe physician diagnosis it as an autoimmune disorder caused due to development of lgG antibodies. He is suffering from
a) Rheumatoid Arthritis
b) Myasthenia Gravis
c) Systemic lupus erythematosus
d) Multiple sclerosis
2) The disorder of neuromuscular junction caused by antibodies against Calcium channels is
a) Myasthenia Gravis
b) Tetanyy
c) Lambert Eaton Syndrome
d) McArdle Disease
3) the drug most commonly used to treat Myasthenia gravis has which mechanism of action
a) It Stimulates muscle fiber by Acetylcholine like action
b) It stimulates Neuromuscular junction by inactivating Acetylcholinesterase
c) It destroys the antibodies produced against acetylchoine receptors
d) It lowers the muscle action potential
4) Which of the following does not play a direct role in the process of transcription?
A) Helicase
B) RNA polymerase
C) Chain-terminating sequence
D) "Activated" RNA molecules
E) Promoter sequence
5) Which statement about feedback control systems is incorrect?
A) Most control systems of the body act by negative feedback
b)Positive feedback usually promotes stability in a system
C) Generation of nerve actions potentials involves positive feedback
D) Feed-forward control is important in regulating muscle activity
6) Which of the following cell organelles is responsible forproducing adenosine triphosphate (ATP), the energycurrency of the cell?
A) Endoplasmic reticulum
B) Mitochondria
C) Lysosomes
D) Golgi apparatus
E) Peroxisomes
7) "Redundancy" or "degeneration" of the genetic code occurs during which step of protein synthesis?
A) DNA replication
B) Transcription
C) Post-transcriptional modification
D) Translation
E)Protein glycosylation
8) Simple diffusion and facilitated diffusion share which of the following characteristics?
A) Can be blocked by specific inhibitors
B) Do not require adenosine triphosphate (ATP)
C) Require transport protein
D) Saturation kinetics
E) Transport solute against concentration gradient
9) Which of the following best describes the changes incell volume that will occur when red blood cells (previously equilibrated in a 280- milliosmolar solution of Nacl are placed in aa solution of 140-milimolar Nacl containing 20-millimolar urea, a relatively large butpermeant molecule?
A) Shrink, then swell and lyse
B) Shrink, then return to original volume
C) Swell and lyse
D) Swell, then return to original volume
E) No change in cell volume
10) Which of the following best describes an attribute ofvisceral 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
11) The resting potential of a myelinated nerve fiber is primarily dependent on the concentration gradient of which of the following ions?
A) Cat+
B) Cl-
C) HCO3-
D) K+
E) Na+
12) 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
13) Weight lifting 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)Increase in skeletal muscle blood supply
D) Increase in the number of motor neurons
E) Increase in the number of neuromuscular junctions
14) A17-year-old to soccer player sustained a fractureto the left tibia. After her lower leg has been in a cast for 8 weeks, she is surprised to find that the left gastrocnemius muscle is significantly smaller in circumference than it was before the fracture. What is the most likely explanation?
a) Decrease in the number of individual muscle fibers in the
b) Decrease in blood flow to the muscle caused by
c) Temporary reduction in actin and myosin protein
d) Increase in glycolytic activity in the affected muscle
e)left gastrocnemius constriction from the cast synthesis
15) Smooth muscle that exhibits rhythmical contraction in the absence of external stimuli also necessarily exhibits which of the following?
A) "Slow" voltage-sensitive Cat+ channels
B) Intrinsic pacemaker wave activity
C) Higher resting cytosolic Ca++ concentration
D) Hyperpolarized membrane potential
E) Action potentials with "plateaus"
16) The sensitivity of the smooth muscle Contractile apparatus to calcium iS Known to increase in the steady stateunder normal conditions. This increase in calcium sensitivity can be attributed to a decrease in the levels ofwhich of the following Substances?
A) Actin
B) Adenosine triphosphate (ATP)
C) Calcium-calmodulin complex
D) Calmodulin
E) Myosin light chain phosphatase (MLCP)
17) A 42-year-old man with myasthenia gravis is notes increased muscle strength when he is treated with an acetylcholinesterase AChE)inhibitor.he basis for his improvement is increased
a) amount of acetylcholine (ACh) released from motor nerves
b) levels of ACh at the muscle end plates
c) number of ACh receptors on the muscle end plates
d) amount of norepinephrine released from motor nerves
e) synthesis of norepinephrine in motor nerves
18) The velocity of conduction of action potentials along a nerve will be increased by
a) stimulating the Na+-K+ pump
b) inhibiting the Na+-K+ pump
c) decreasing the diameter of the nerve
d) myelinating the nerve
e) lengthening the nerve fiber
19) Degeneration of dopaminergic neurons has been implicated in
a) schizophrenia
b) Parkinson's disease
c) myasthenia gravis
d) curare poisoning
20) A new drug is developed that blocks the transporter for H+ secretion in gastric parietal cells. Which of the following transport processes is being inhibited?
a) Simple diffusion
b) Facilitated diffusion
c)) Primary active transport
d) Cotransport
e) Countertransport
21) Which of the following causes rigor in
skeletal muscle?
a) No action potentials in motoneurons
b) An increase in intracellular Ca2+ level
c) A decrease in intracellular Ca2+ level
d) An increase in adenosine triphosphate ATP level
e) A decrease in ATP level
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