of, relating to, or of the nature of preference: preferential policies. 2. showing or giving preference: a preferential hiring system. 3. receiving or enjoying preference, as a country in trade relations; favored. Origin of preferential.
Histamine dilates post-capillary venules, activates the endothelium, and increases blood vessel permeability. This leads to local edema (swelling), warmth, redness, and the attraction of other inflammatory cells to the site of release. It also depolarizes nerve endings (leading to itching or pain).
: The histamine reaction in relation to the immune response (in both allergic reactions and immune reactions) serves two main functions: 1. It causes what is called âvasodilation.â Vasodilation occurs when the muscular walls that surround blood vessels are relaxed, causing the interior of the blood vessel to widen.2.istamine in Sleep: The body regulates the amount of histamine in circulation and maintains a careful balance. This is most important with keeping the body awake and alert. Antihistamines are known to cause drowsiness and sleep.