Which statement regarding alpha 1 and alpha 2 receptors is correct?
Alpha 1 agonist and alpha 2 antagonist increase blood pressure
Alpha 1 agonist and alpha 2 agonist decrease blood pressure
Alpha 1 and alpha 2 agonist increase blood pressure
Alpha 1 antagonist and alpha 2 agonist decrease blood pressure
The Correct Answer is A
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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["A","C"]
Explanation
Choice A Reason:
Acidosis is indicated by a pH lower than the normal range of 7.35-7.45. In this case, the patient’s pH is 7.3, which confirms acidosis. Acidosis can be caused by either respiratory or metabolic factors, but the low pH alone confirms the presence of acidosis.
Choice B Reason:
Compensation refers to the body’s attempt to return the pH to normal by adjusting the levels of CO2 or HCO3-. In this case, the HCO3- level is within the normal range (22-26 mEq/L), indicating that there is no metabolic compensation occurring. Therefore, this choice is incorrect.
Choice C Reason:
Respiratory acidosis is indicated by an elevated PaCO2 level, which is higher than the normal range of 36-44 mmHg. The patient’s PaCO2 is 48 mmHg, suggesting that the acidosis is due to respiratory factors. This is consistent with the patient’s history of smoking and symptoms of respiratory distress.
Choice D Reason:
Alkalosis is indicated by a pH higher than the normal range of 7.35-7.45. Since the patient’s pH is 7.3, which is below the normal range, this indicates acidosis, not alkalosis. Therefore, this choice is incorrect.
Choice E Reason:
Metabolic acidosis is indicated by a low HCO3- level. In this case, the patient’s HCO3- level is within the normal range (25 mEq/L), indicating that the acidosis is not metabolic. Therefore, this choice is incorrect.
Correct Answer is D
Explanation
Choice A: Calcium
Calcium plays a crucial role in various physiological processes, including muscle contraction, blood clotting, and nerve transmission. While calcium is essential for maintaining overall health, it is not directly associated with changes in blood pH. Calcium levels are tightly regulated by hormones such as parathyroid hormone (PTH) and calcitonin, but these do not significantly influence blood pH.
Choice B: Sodium
Sodium is a major extracellular electrolyte that helps regulate fluid balance, nerve function, and muscle contraction. Although sodium is vital for maintaining osmotic balance and blood pressure, it does not directly affect blood pH. Sodium levels are primarily controlled by the kidneys and hormones like aldosterone, which do not have a direct impact on the acid-base balance of the blood.
Choice C: Magnesium
Magnesium is involved in over 300 biochemical reactions in the body, including protein synthesis, muscle and nerve function, and blood glucose control. While magnesium is important for overall health, it does not have a direct role in altering blood pH. Magnesium levels are regulated by the kidneys and are essential for maintaining normal muscle and nerve function, but they do not directly influence the acid-base balance.
Choice D: Potassium
Potassium is a key intracellular electrolyte that plays a significant role in maintaining the acid-base balance of the blood. Changes in potassium levels can affect the pH of the blood. For example, hyperkalemia (high potassium levels) can lead to acidosis, while hypokalemia (low potassium levels) can lead to alkalosis. Potassium helps regulate the hydrogen ion concentration in the blood, which directly impacts the pH. Therefore, potassium is the electrolyte most closely associated with changes in blood pH.
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