Final answer:
Histamine is a chemical mediator released by mast cells and is associated with allergies and hypersensitivity reactions. It stimulates various bodily responses such as mucus secretion, tear formation, itching, sneezing, vasodilation, bronchiole constriction, vomiting, relaxation of intestinal muscles, and diarrhea.
Step-by-step explanation:
Histamine is a chemical mediator released by mast cells in the body. It stimulates mucus secretion, tear formation, and causes itching, sneezing, and itching when it interacts with nerve endings. Histamine can also cause vasodilation, bronchiole constriction, vomiting, relaxation of intestinal muscles, and diarrhea. It is associated with allergies and hypersensitivity reactions.