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.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A: Beta 2 Agonist Decreases Blood Pressure
Beta 2 agonists primarily cause bronchodilation and vasodilation, which can lead to a decrease in blood pressure. However, this is not their primary function, and they are more commonly associated with the relaxation of smooth muscles in the airways.
Choice B: Beta 1 Agonist Increases Blood Pressure
Beta 1 receptors are primarily located in the heart. Activation of these receptors increases heart rate and contractility, which in turn increases cardiac output and blood pressure. Therefore, beta 1 agonists are known to increase blood pressure.
Choice C: Beta 2 Agonist Reduces Blood Pressure
Similar to choice A, beta 2 agonists can cause vasodilation, which may reduce blood pressure. However, this is not their primary therapeutic use, and they are mainly used for their bronchodilatory effects.
Choice D: Beta 1 Agonist Reduces Blood Pressure
Beta 1 agonists increase heart rate and contractility, leading to an increase in blood pressure. Therefore, this statement is incorrect as beta 1 agonists do not reduce blood pressure.
Correct Answer is A
Explanation
Choice A: Metabolic Acid Deficit (Metabolic Alkalosis)
Vomiting or continuous nasogastric suctioning leads to the loss of gastric contents, which are rich in hydrochloric acid (HCl)1. This loss results in a decrease in the body’s acid levels, leading to a condition known as metabolic alkalosis2. Metabolic alkalosis is characterized by an increase in blood pH due to the loss of hydrogen ions (H+) and an increase in bicarbonate (HCO3-) levels. This condition can cause symptoms such as muscle twitching, hand tremors, and light-headedness.
Choice B: Carbonic Acid Excess (Respiratory Acidosis)
Carbonic acid excess, or respiratory acidosis, occurs when there is an accumulation of carbon dioxide (CO2) in the blood, leading to a decrease in blood pH3. This condition is typically caused by respiratory issues such as hypoventilation, chronic obstructive pulmonary disease (COPD), or severe asthma. It is not directly related to vomiting or nasogastric suctioning, which primarily affect the metabolic component of acid-base balance.
Choice C: Metabolic Acid Excess (Metabolic Acidosis)
Metabolic acidosis is characterized by a decrease in blood pH due to an accumulation of metabolic acids or a loss of bicarbonate. Common causes include renal failure, diabetic ketoacidosis, and severe diarrhea. Vomiting or nasogastric suctioning, which result in the loss of gastric acid, do not lead to metabolic acidosis but rather to metabolic alkalosis.
Choice D: Carbonic Acid Deficit (Respiratory Alkalosis)
Respiratory alkalosis occurs when there is a decrease in carbon dioxide levels in the blood, leading to an increase in blood pH. This condition is often caused by hyperventilation due to anxiety, fever, or high altitude. It is not related to the loss of gastric contents through vomiting or nasogastric suctioning, which primarily affect the metabolic component of acid-base balance.
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