Sympathetic activation leads to
A)relaxation in skeletal muscle of bronchioles, causing bronchodilation.
B)contraction of smooth muscles of bronchioles, causing bronchoconstriction.
C)relaxation in smooth muscles of bronchioles, causing bronchodilation.
D)relaxation of smooth muscles of bronchioles, resulting in bronchoconstriction.
E)contraction of smooth muscles of bronchioles, causing bronchodilation.
The following is a list of some of the structures of the respiratory tree: 1. secondary bronchi
2. tertiary bronchi
4. primary bronchi
The order in which air passes through these structures beginning at the trachea is
A)4, 1, 2, 3.
B)3, 2, 1, 4.
C)2, 3, 1, 4.
D)4, 1, 3, 2.
E)1, 2, 3, 4.
The walls of the alveoli are lined by
A)stratified cuboidal epithelium.
C)simple squamous epithelium.
D)loose connective tissue.
The actual sites of gas exchange within the lungs include