Question

Branches of the nervous system, which can cause relaxation of airway smooth muscle, include which of the following?

1. Sympathetic nerves
2. Parasympathetic nerves
3. Nonadrenergic, noncholinergic (NANC) inhibitory nerves

a. 1 only
b. 2 only
c. 1 and 2 only
d. 1, 2, and 3

Answer 1

The branches of the nervous system that can cause relaxation of airway smooth muscle include sympathetic nerves, parasympathetic nerves, and nonadrenergic, noncholinergic (NANC) inhibitory nerves. Hence, d is the correct option.

Step-by-step explanation:

The branches of the nervous system that can cause relaxation of airway smooth muscle include:

1. Sympathetic nerves: The sympathetic nervous system stimulates bronchodilation, which is the relaxation of the airway smooth muscle.
2. Parasympathetic nerves: The parasympathetic system causes bronchoconstriction, which is the narrowing of the airway.
3. Nonadrenergic, noncholinergic (NANC) inhibitory nerves: These nerves also contribute to the relaxation of airway smooth muscle.

Therefore, the correct answer is d. 1, 2, and 3.