Uses of Histamines

Histamines are chemicals released by the human immune system during an allergic reaction. This is just one of the body's many defenses against infection. The four receptors found in humans have been labeled H1 through H4 and are produced in localized places in response to germs and bacteria. Once histamines are released, they result in a variety of effects, the most popular being watery, itchy eyes, congestion, and sneezing. Histamines do a lot more than just make a person miserable during pollen season.

Wounds

• The most common receptor is the H1 receptor. This is localized in parts of the body that could get injured -- your hands and feet, skin, and muscles. When a part of the body is cut, histamines allow the blood vessels to dilate, increasing blood flow to the area and washing away harmful bacteria. This is the reason why an injured area can become red, swollen and painful. It's another reason why a wound itches as it heals.

Gastric Activity

• The H2 receptors are located in the cells of the stomach and, once activated, trigger the release of stomach acid and regulates intestinal secretions. People with intense reactions to these receptors experience symptoms like ulcers, heartburn and indigestion. Common H2- receptor blockers include Pepcid, Zantac and Tums.

Sleep Schedule

• Histamine H3 receptors are found in the brain and control functions related to the central nervous system. When these receptors are triggered, they decrease the release of serotonin, acetylcholine, and norepinephrine which is thought to be related to a sleep routine. The fourth receptors, or H4, are concentrated in the lower GI tract and bone marrow. Since these receptors have only recently been discovered, their action is still unknown.

Antihistamines

• An effective way to control allergic symptoms is to stop the histamines with antihistamines, over-the-counter medications which prevent the allergen from exerting their effects. Antihistamines bind to the released histamine, effectively stopping their reactions. While antihistamines are necessary and helpful in certain cases, they should be taken in moderation because histamines are still not fully understood.