The nurse is teaching nursing students about the concept of medications’ half-life. The nurse asks students: If we administer 10 mg of medication X, which has a half-life of one day, to the patient, how much medication will remain in the patient’s body after three days?
0 mg, the medication will be out of the patient’s body.
1.25 mg.
5 mg.
1 mg.
The Correct Answer is B
Choice A Reason:
The statement that the medication will be completely out of the patient’s body after three days is incorrect. The half-life of a drug indicates the time it takes for the concentration of the drug in the body to reduce by half. After one half-life (one day), 50% of the drug remains. After two half-lives (two days), 25% remains. After three half-lives (three days), 12.5% remains. Therefore, some amount of the drug will still be present in the body after three days.
Choice B Reason:
To calculate the amount of medication remaining after three days, we use the half-life formula. Starting with 10 mg, after one day (one half-life), 5 mg remains. After two days (two half-lives), 2.5 mg remains. After three days (three half-lives), 1.25 mg remains. This calculation shows that 1.25 mg of the medication will still be in the patient’s body after three days.
Choice C Reason:
The choice of 5 mg is incorrect because it represents the amount of medication remaining after one half-life (one day), not three half-lives. After one day, 50% of the initial dose remains, which is 5 mg. However, the question asks for the amount remaining after three days.
Choice D Reason:
The choice of 1 mg is also incorrect. After three half-lives, the amount of medication remaining is 12.5% of the initial dose. For an initial dose of 10 mg, this would be 1.25 mg, not 1 mg. The calculation must accurately reflect the reduction by half for each half-life period.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A: Alpha 1 Agonist and Alpha 2 Antagonist Increase Blood Pressure
Alpha 1 receptors are primarily located on the smooth muscles of blood vessels. When activated by an agonist, these receptors cause vasoconstriction, which increases blood pressure. On the other hand, alpha 2 receptors are found on presynaptic nerve terminals and act to inhibit the release of norepinephrine. An antagonist at alpha 2 receptors would prevent this inhibition, leading to increased norepinephrine release, further promoting vasoconstriction and increasing blood pressure. Therefore, the combination of an alpha 1 agonist and an alpha 2 antagonist would synergistically increase blood pressure.
Choice B: Alpha 1 Agonist and Alpha 2 Agonist Decrease Blood Pressure
Alpha 1 agonists increase blood pressure by causing vasoconstriction. Alpha 2 agonists, however, decrease blood pressure by inhibiting norepinephrine release, leading to vasodilation. Therefore, this combination would not decrease blood pressure as the effects of the alpha 1 agonist would counteract the effects of the alpha 2 agonist.
Choice C: Alpha 1 and Alpha 2 Agonist Increase Blood Pressure
While alpha 1 agonists increase blood pressure through vasoconstriction, alpha 2 agonists actually decrease blood pressure by reducing norepinephrine release. Therefore, this statement is incorrect as the combined effect would not result in an increase in blood pressure.
Choice D: Alpha 1 Antagonist and Alpha 2 Agonist Decrease Blood Pressure
Alpha 1 antagonists block the vasoconstrictive action of alpha 1 receptors, leading to vasodilation and a decrease in blood pressure. Alpha 2 agonists also decrease blood pressure by inhibiting norepinephrine release. Therefore, this combination would indeed decrease blood pressure, making this statement partially correct but not the best answer compared to choice A.
Correct Answer is C
Explanation
Choice A Reason:
The sympathetic nervous system (SNS) is responsible for the “fight or flight” response, which prepares the body to respond to perceived threats. One of the primary effects of SNS activation is an increase in heart rate. This is achieved through the release of catecholamines like adrenaline, which stimulate the heart to pump more blood to vital organs and muscles.
Choice B Reason:
Another effect of SNS activation is an increase in blood glucose levels. This occurs because the body needs more energy to respond to stress. The SNS stimulates the liver to release glucose into the bloodstream, ensuring that muscles and other tissues have enough energy to function effectively during a stressful situation.
Choice C Reason:
The correct answer is that SNS activation does not increase GI motility and movement. In fact, it has the opposite effect. During a “fight or flight” response, the body prioritizes functions that are critical for immediate survival, such as increased heart rate and blood flow to muscles. As a result, non-essential functions like digestion are slowed down. The SNS decreases GI motility and movement to divert energy and blood flow to more critical areas.
Choice D Reason:
SNS activation also leads to an increase in blood pressure. This is achieved by constricting blood vessels and increasing the force of heart contractions. The purpose of this response is to ensure that enough blood and oxygen are delivered to essential organs and muscles during a stressful situation.
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