Final answer:
Histamines released by mast cells cause blood vessels to vasodilate, which is the widening of blood vessels, leading to increased blood flow and inflammation symptoms such as redness, heat, and swelling.
Step-by-step explanation:
Histamines, which are chemical signals released by mast cells in response to tissue injury, cause blood vessels in the area to vasodilate. This process of vasodilation refers to the widening of blood vessels, which increases blood flow to the site of injury or infection. This increase in blood flow causes the symptoms associated with inflammation: redness, heat, and swelling (edema), along with the sensation of pain due to the swollen tissues activating pain receptors.
The release of histamines and their effect on blood vessels is an important part of the body's immune response, as it facilitates the entry of white blood cells and other immune cells to the site of injury, where they can combat any potential invaders such as bacteria or viruses. Furthermore, in case of an allergic response, medications like antihistamines can decrease symptoms by blocking the action of histamine on its receptors.