An allergy is an abnormal immune reaction to a normally harmless substance. When an allergic person encounters the trigger substance, their body releases chemicals like histamine that cause allergy symptoms such as sneezing, itching, hives and watery eyes. Common allergies include respiratory, skin, food, asthma, drugs and insect stings. Hives occur when histamine is released into the skin from mast cells, causing blood vessels to leak fluid and form raised, itchy welts on the skin. Treatment for hives typically involves antihistamines. Phagocytosis is the process where phagocytes like white blood cells engulf and digest microbes and debris to defend against infection.

1. Chapter 6 PresentationLymphatic & ImmuneSystemBy: Laura E Garcia

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 allergiesSkin allergies Food allergiesAsthmaDrug allergiesInsect sting allergies

4. The most common symptoms include:Runny noseStuffy nose Sneezing Nasal itching (rubbing) Itchy ears and throat Post nasal drip (throat clearing)Hives

5. HivesThe 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. Phagocytosisprocess 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.