2. ALLERGY An allergy is an abnormal reaction by a person's immune system against a normally harmless substance. A person without allergies would have no reaction to this substance, but when a person who is allergic encounters the trigger, the body reacts by releasing chemicals which cause allergy symptoms.
3. Body Response: Mast cells release histamine when an allergen is encountered. The histamine response can produce sneezing, itching, hives and watery eyes. Types of Allergies Respiratory allergies Skin allergies Food allergies Asthma Drug allergies Insect sting allergies
4. The most common symptoms include: Runny nose Stuffy nose Sneezing Nasal itching (rubbing) Itchy ears and throat Post nasal drip (throat clearing) Hives
5. Hives The skin condition we call hives is referred to in medical terms as urticaria. A hive, or wheal, is a symptom of urticaria. A hive, or wheal, is a circular, red, spongy lesion that evolves and changes over minutes to hours. It is usually surrounded by an area of redness called a flare. Hives can vary in size from a few millimeters to giant hives covering a whole extremity.
6. Cellular Look at Hives Hives occur in response to chemical called histamine into the skin. Histamine is located in certain white blood cells called mast cells, which are plentiful in the skin around capillaries. If properly triggered, these mast cells release granules of chemicals, the most powerful of which is histamine. Histamine causes the cells making up the blood vessels to contract allowing fluid to leak out of the blood vessel. Red blood cells are too large to leak out of these holes. Injecting histamine into the skin causes a triple response of redness, leaking of fluid producing a hive, and the flare or redness around the hive.
7. Treatment of Hives The treatment of the physical hives is specific to the type that is diagnosed. In the majority of cases of chronic hives, the cause factor can not be determined. For these people, antihistamines is the main treatment.
8. Phagocytosis process in which phagocytes engulf and digest microorganisms and cellular debris; an important defense against infection. Phagocytes: cell, such as a white blood cell, that engulf and absorbs waste material, harmful microorganisms, or other foreign bodies in the bloodstream and tissues.
