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What electrolyte inactivates troponin and allows actin and myosin to form a bridge enabling fibers to contract?

A. Magnesium.

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.

B. Sodium.

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.

C. Potassium.

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.

D. Calcium.

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.

This question is an excerpt from Nurse Dive's nursing test bank - ATI Advanced Pharmacology Final Proctored Exam. Take the full exam now


Full Explanation

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.


Similar Questions

QUESTION
The adverse effects of xanthene are related to the theophylline levels in the blood and include brain damage.

A. True.

True. Xanthine derivatives like theophylline can cause serious adverse effects, including brain damage, when blood levels become too high. It is critical to monitor theophylline levels to prevent toxicity and associated neurological complications.

B. False.

False. If xanthine levels remain within therapeutic ranges, the risk of brain damage is minimized. However, this statement is incorrect as it does not acknowledge the potential severity of the adverse effects linked to elevated theophylline levels.

Full Explanation

Choice A rationale

True. Xanthine derivatives like theophylline can cause serious adverse effects, including brain damage, when blood levels become too high. It is critical to monitor theophylline levels to prevent toxicity and associated neurological complications.

Choice B rationale

False. If xanthine levels remain within therapeutic ranges, the risk of brain damage is minimized. However, this statement is incorrect as it does not acknowledge the potential severity of the adverse effects linked to elevated theophylline levels.

QUESTION
When the nurse administers a cholinergic agonist to the patient the nurse's expectation is what system will be stimulated.

A. Central nervous system.

Cholinergic agonists primarily stimulate the parasympathetic nervous system rather than the central nervous system, affecting activities like digestion, salivation, and decreased heart rate.

B. Parasympathetic nervous system.

Parasympathetic nervous system is the correct answer. Cholinergic agonists mimic acetylcholine and stimulate parasympathetic responses, promoting rest-and-digest functions such as reducing heart rate and enhancing glandular secretions.

C. Sympathetic nervous system.

The sympathetic nervous system is not stimulated by cholinergic agonists. Instead, this system is activated by adrenergic agonists, which prepare the body for fight-or-flight responses, increasing heart rate and blood pressure.

D. Voluntary nervous system.

Voluntary nervous system control is not the primary target of cholinergic agonists. This system governs skeletal muscle movement and is influenced by neuromuscular junctions rather than the autonomic responses modulated by cholinergic drugs. .

Full Explanation

Choice A rationale

Cholinergic agonists primarily stimulate the parasympathetic nervous system rather than the central nervous system, affecting activities like digestion, salivation, and decreased heart rate.

Choice B rationale

Parasympathetic nervous system is the correct answer. Cholinergic agonists mimic acetylcholine and stimulate parasympathetic responses, promoting rest-and-digest functions such as reducing heart rate and enhancing glandular secretions.

Choice C rationale

The sympathetic nervous system is not stimulated by cholinergic agonists. Instead, this system is activated by adrenergic agonists, which prepare the body for fight-or-flight responses, increasing heart rate and blood pressure.

Choice D rationale

Voluntary nervous system control is not the primary target of cholinergic agonists. This system governs skeletal muscle movement and is influenced by neuromuscular junctions rather than the autonomic responses modulated by cholinergic drugs. .

QUESTION
A 54-year-old man has a myocardial infarction, resulting in left-sided heart failure.
The nurse caring for the man is most concerned that he will develop edema in what area of the body.

A. Peripheral.

Peripheral edema is more commonly associated with right-sided heart failure rather than left-sided. This is because right-sided heart failure leads to systemic venous congestion, causing fluid to accumulate in the peripheral tissues, particularly in the legs and ankles.

B. Pulmonary.

Pulmonary edema is a major concern in left-sided heart failure due to the inability of the left ventricle to effectively pump blood out to the systemic circulation. This results in blood backing up into the pulmonary veins, leading to fluid accumulation in the lungs.

C. Liver.

Liver edema, or hepatomegaly, is more typically seen in right-sided heart failure, where the failure of the right ventricle causes blood to back up into the systemic circulation, affecting the liver and other organs.

D. Abdominal.

Abdominal edema, or ascites, is also more associated with right-sided heart failure. This condition occurs due to increased pressure in the veins and capillaries, leading to fluid leakage into the abdominal cavity.

Full Explanation

Choice A rationale

Peripheral edema is more commonly associated with right-sided heart failure rather than left-sided. This is because right-sided heart failure leads to systemic venous congestion, causing fluid to accumulate in the peripheral tissues, particularly in the legs and ankles.

Choice B rationale

Pulmonary edema is a major concern in left-sided heart failure due to the inability of the left ventricle to effectively pump blood out to the systemic circulation. This results in blood backing up into the pulmonary veins, leading to fluid accumulation in the lungs.

Choice C rationale

Liver edema, or hepatomegaly, is more typically seen in right-sided heart failure, where the failure of the right ventricle causes blood to back up into the systemic circulation, affecting the liver and other organs.

Choice D rationale

Abdominal edema, or ascites, is also more associated with right-sided heart failure. This condition occurs due to increased pressure in the veins and capillaries, leading to fluid leakage into the abdominal cavity.