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 B
Explanation
Choice A Reason:
An increase in HCO3- (bicarbonate) is not typically associated with diarrhea and lower intestinal fluid losses. In fact, the opposite is true. Diarrhea often leads to a loss of bicarbonate, which can result in metabolic acidosis. Therefore, this choice is incorrect.
Choice B Reason:
This is the correct answer. Diarrhea and other lower intestinal fluid losses lead to a decrease in HCO3- levels. The loss of bicarbonate from the body results in a lower pH, contributing to metabolic acidosis. This condition occurs because bicarbonate is a key buffer that helps maintain the acid-base balance in the blood.
Choice C Reason:
An increase in the chance of alkalosis is not typically associated with diarrhea. Alkalosis refers to a condition where the pH of the blood is higher than normal, which can occur due to a loss of hydrogen ions or an increase in bicarbonate. However, diarrhea usually causes a loss of bicarbonate, leading to acidosis rather than alkalosis.
Choice D Reason:
Saying that diarrhea has no effect on the pH of the blood is incorrect. Diarrhea can significantly impact the acid-base balance in the body by causing a loss of bicarbonate, leading to metabolic acidosis. Therefore, this choice is incorrect.
Correct Answer is C
Explanation
Choice A: Hypoventilation
Hypoventilation refers to inadequate ventilation that leads to an increased concentration of carbon dioxide (CO2) in the blood, resulting in respiratory acidosis. This condition is characterized by a decrease in blood pH due to the accumulation of CO2, which forms carbonic acid. Hypoventilation does not cause metabolic acidosis, as it primarily affects the respiratory component of acid-base balance.
Choice B: Massive Blood Transfusion
Massive blood transfusion can lead to metabolic alkalosis rather than metabolic acidosis. This is because stored blood products often contain citrate, which is metabolized to bicarbonate in the liver, increasing the blood’s alkalinity. Additionally, the transfusion of large volumes of blood can dilute the plasma bicarbonate concentration, but this typically does not result in metabolic acidosis.
Choice C: Kidney Failure
Kidney failure is a common cause of metabolic acidosis. The kidneys play a crucial role in maintaining acid-base balance by excreting hydrogen ions (H+) and reabsorbing bicarbonate (HCO3-). When the kidneys fail, they are unable to remove sufficient acids from the blood, leading to an accumulation of metabolic acids and a decrease in blood pH. This condition is known as metabolic acidosis and can result from chronic kidney disease (CKD) or acute kidney injury (AKI).
Choice D: Hyperventilation
Hyperventilation leads to respiratory alkalosis, not metabolic acidosis. This condition occurs when there is excessive ventilation, causing a decrease in CO2 levels in the blood and an increase in blood pH. Hyperventilation reduces the concentration of carbonic acid, leading to an alkaline state. It does not contribute to metabolic acidosis, which involves an imbalance in the metabolic components of acid-base regulation.
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