The nurse recognizes that adrenergic drugs cause relaxation of the bronchi and bronchodilation by stimulating which type of receptors?

The nurse recognizes that adrenergic drugs cause relaxation of the bronchi and bronchodilation by stimulating which type of receptors?

A Alpha 1 adrenergic
B Beta2 adrenergic
C Beta adrenergic
D Dopaminergic

The Correct answer and Explanation is:

The correct answer is B. Beta2 adrenergic.

Explanation:

Adrenergic drugs, also known as sympathomimetics, mimic the effects of the sympathetic nervous system by stimulating adrenergic receptors. The sympathetic nervous system, part of the autonomic nervous system, is responsible for the “fight or flight” response, which includes increasing heart rate, dilating pupils, and expanding the airways (bronchodilation).

There are several types of adrenergic receptors, primarily classified as alpha (α) and beta (β) receptors. Each receptor subtype has different physiological effects based on its location and function in the body:

1. Alpha1 adrenergic receptors (A) are primarily involved in vasoconstriction and increasing blood pressure. They are found in the blood vessels and the smooth muscle of various organs but are not significantly involved in bronchodilation.
2. Beta adrenergic receptors (C) are a broad category that includes both Beta1 and Beta2 receptors. Beta1 receptors are mainly located in the heart, where they increase heart rate and contractility. Beta2 receptors, on the other hand, are found in the smooth muscle of the lungs, among other tissues.
3. Beta2 adrenergic receptors (B) are specifically involved in the relaxation of bronchial smooth muscle, leading to bronchodilation. Stimulation of these receptors by adrenergic drugs, such as albuterol (a common bronchodilator), results in the widening of the airways, making it easier to breathe. This is particularly important in conditions like asthma and chronic obstructive pulmonary disease (COPD), where the airways can become constricted.
4. Dopaminergic receptors (D) are a different class of receptors that respond to dopamine, a neurotransmitter involved in various functions, including movement and the reward system. These receptors are not involved in bronchodilation.

Therefore, adrenergic drugs that cause bronchodilation primarily act by stimulating Beta2 adrenergic receptors. These receptors are the target for medications used to treat respiratory conditions that cause bronchoconstriction, such as asthma and COPD. By relaxing the smooth muscle of the bronchi, Beta2 adrenergic agonists help to open up the airways, improving airflow and reducing respiratory distress.