Final answer:
Mast cells are white blood cells in connective tissue integral to the immune system, releasing chemical mediators like histamine and heparin that cause inflammatory and allergic reactions.
Step-by-step explanation:
What are Mast Cells?
Mast cells are a type of white blood cell found in connective tissue. They play an essential role in the body's immune system by releasing chemicals that mediate inflammatory responses. When antigens bind to antibodies known as Immunoglobulin E (IgE) on the surface of mast cells, it triggers the cells to release chemical mediators such as histamine, heparin, cytokines, serotonin, and bradykinin. These chemical mediators cause symptoms like itching, swelling, redness, and vasodilation—common signs of an allergic reaction. Histamine is particularly known for causing increased blood flow and inflammation at the site of injury or infection.
Mast cells contain cytoplasmic granules packed with these mediators and, upon a second exposure to the antigen, will undergo degranulation—a process where they release these substances into the surrounding tissue. The IgE primed mast cell degranulation is crucial in hypersensitivity reactions, often leading to signs and symptoms associated with allergies.