Author Question: Why are adrenergic agonists such as epinephrine given parenterally or by inhalation instead of ... (Read 65 times)

pragya sharda · **on:** Jul 23, 2018

Why are adrenergic agonists such as epinephrine given parenterally or by inhalation instead of orally?

1. They are not easily digested in the gastrointestinal tract.
2. They produce toxic by-products in the blood.
3. They are rapidly absorbed by the blood.
4. They are metabolized by the enzyme COMT in the intestinal tract.

Question 2

One of the reasons epinephrine causes an intense fight-or-flight response throughout the body is because it stimulates which receptors?

1. The alpha receptors only
2. All four types of adrenergic receptors
3. The beta-2 receptors only
4. The beta-1 receptors only

Sarahjh · **Reply #1 on:** Jul 23, 2018

Answer to Question 1

Correct Answer: 4
Rationale 1: Adrenergic agonists are not digested in the gastrointestinal tract.
Rationale 2: No toxic by-products are produced.
Rationale 3: Adrenergic agonists are not rapidly absorbed by the blood.
Rationale 4: Epinephrine is metabolized by the enzymes MAO and COMT in the liver and in most tissues; hence, it is not absorbed orally.
Global Rationale: Epinephrine is metabolized by the enzymes MAO and COMT in the liver and in most tissues; hence, it is not absorbed orally. Adrenergic agonists are not digested in the gastrointestinal tract. No toxic by-products are produced. Adrenergic agonists are not rapidly absorbed by the blood.

Answer to Question 2

Correct Answer: 2
Rationale 1: There are two alpha receptors: alpha-1 and alpha-2. Stimulation of alpha-1 receptors by epinephrine causes pupillary dilatation; stimulation of alpha-2 receptors causes blood pressure to rise and more blood to flow to the peripheral muscles, which is very helpful in the fight-or-flight response. But epinephrine stimulates all four types of receptors.
Rationale 2: Epinephrine stimulates all four types of receptors, and hence causes an intense fight-or-flight response, the effects of which are seen all over the body.
Rationale 3: Epinephrine stimulates all four types of receptors, not just the beta-2 receptors. Stimulation of beta-2 receptors in the bronchi causes dilatation of the bronchi, which allows easier breathing during a fight-or-flight response.
Rationale 4: Epinephrine stimulates all four types of receptors, not just the beta-1 receptors. Beta-1 receptors in the heart cause the heart to beat faster and to provide more blood to the body's tissues.
Global Rationale: Epinephrine stimulates all four types of receptors, and hence causes an intense fight-or-flight response, the effects of which are seen all over the body. There are two alpha receptors: alpha-1 and alpha-2. Stimulation of alpha-1 receptors by epinephrine causes pupillary dilatation; stimulation of alpha-2 receptors causes blood pressure to rise and more blood to flow to the peripheral muscles, which is very helpful in the fight-or-flight response. But epinephrine stimulates all four types of receptors.