What electrolyte inactivates troponin and allows actin and myosin to form a bridge enabling fibers to contract?
Magnesium.
Sodium.
Potassium.
Calcium.
The Correct Answer is D
Choice A rationale
Magnesium plays a role in various cellular functions, including enzyme activity and muscle contraction, but it does not directly inactivate troponin to enable actin and myosin interaction.
Choice B rationale
Sodium is essential for action potential generation and nerve impulse transmission but does not directly influence troponin activity or muscle contraction through actin and myosin bridge formation.
Choice C rationale
Potassium is critical for maintaining cellular resting membrane potential and repolarization of cells but does not play a direct role in inactivating troponin to facilitate muscle contraction.
Choice D rationale
Calcium is the electrolyte that inactivates troponin, allowing actin and myosin to form cross-bridges and contract muscle fibers. Calcium binds to troponin, causing a conformational change that exposes binding sites for myosin on actin filaments.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale
Antihistamines can enhance the sedative effects of cyclobenzaprine, increasing the risk of drowsiness and accidents. Patients should avoid combining these medications.
Choice B rationale
Antiemetics are not contraindicated with cyclobenzaprine, although they should be used cautiously due to potential interactions that can increase sedation.
Choice C rationale
Antibiotics do not generally interact significantly with cyclobenzaprine. There are no specific contraindications against their combined use.
Choice D rationale
Alcohol can significantly increase the sedative effects of cyclobenzaprine, leading to enhanced drowsiness, impaired motor functions, and an increased risk of accidents. Patients should avoid alcohol while taking this medication.
Correct Answer is D
Explanation
Choice A rationale
Deoxygenated blood from the lungs would not flow to the left atrium or through the pulmonary artery.
Choice B rationale
Deoxygenated blood from the lungs would not enter the right atrium or flow through the pulmonary artery.
Choice C rationale
Oxygenated blood from the lungs does not enter the right atrium through the pulmonary veins.
Choice D rationale
Correct, oxygenated blood from the lungs enters the left atrium through the pulmonary veins.
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