Which statement regarding alpha 1 and alpha 2 receptors is correct?

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.

Choice A Reason:

Beta2 activation results in bronchodilation. This is a well-known effect where the activation of beta2 adrenergic receptors in the smooth muscle of the airways leads to relaxation and widening of the airways, making it easier to breathe. This effect is commonly utilized in the treatment of asthma and other respiratory conditions.

Choice B Reason:

Beta2 activation also results in glycogenolysis. This process involves the breakdown of glycogen into glucose, which increases blood sugar levels. This effect is part of the body’s response to stress, providing additional energy for the “fight or flight” response.

Choice C Reason:

Beta2 activation results in vasodilation of skeletal muscles. This means that the blood vessels supplying the skeletal muscles widen, increasing blood flow to these muscles. This effect helps to deliver more oxygen and nutrients to the muscles during periods of increased activity.

Choice D Reason:

This is the correct answer. Beta2 activation does not result in the contraction of uterine muscle; rather, it causes relaxation of the uterine smooth muscle. This effect is beneficial in preventing premature labor by reducing uterine contractions. Therefore, the statement that beta2 activation results in contraction of uterine muscle is incorrect and indicates a need for further teaching.