What can the release of histamine and other chemical mediators from the mast cells in the air-ways cause? 1. Bronchoconstriction 2. Bronchodilation 3. Vasoconstriction 4. Vasodilation

a. 2 and 4 only
b. 1 and 3 only
c. 2 and 3 only
d. 1 and 4 only

ANS: D
Mast cells are also found in the submucosa and release numerous and potent vasoactive and bronchoactive substances such as histamine. Histamine causes vasodilation and bronchocon-striction, acting directly on smooth muscle.