Allergies & Autoimmune Diseases

Have you ever started to sneeze and not known why?

A beautiful sea of flowers. A nice sight, unless you have an allergic reaction. It is not uncommon to have reactions to pollen.


Your immune system usually protects you from pathogens and keeps you well. However, like any other body system, the immune system itself can develop problems. Sometimes it responds to harmless foreign substances as though they were pathogens. Sometimes it attacks the body’s own cells. Certain diseases can also attack and damage the immune system and interfere with its ability to defend the body.

An allergy is a disease in which the immune system makes an inflammatory response to a harmless antigen. Any antigen that causes an allergy is called an allergen. Allergens may be inhaled or ingested, or they may come into contact with the skin. Two common causes of allergies. Inhaling ragweed pollen may cause coughing and sneezing. Skin contact with oils in poison ivy may cause an itchy rash. Other common causes of allergies include dust mites, mold, animal dander, insect stings, latex, and certain food and medications. Symptoms of a common allergy such as pollen can include sneezing, a runny nose, nasal congestion and itchy, watery eyes.

The symptoms of allergies can range from mild to severe. Mild allergy symptoms are often treated with antihistamines.

These are drugs that reduce or eliminate the effects of the histamines that cause allergy symptoms. Recall that histamines trigger the inflammatory response. The most severe allergic reaction is called anaphylaxis. This is a life-threatening response caused by a massive release of histamines. It requires emergency medical treatment.

• Allergies occur when the immune system makes an inflammatory response to a harmless antigen.

• An antigen that causes an allergy is called an allergen.

Autoimmune Diseases

Joint pain. Not an uncommon problem as you grow older. Is it due to normal wear and tear on the joints? Possibly. But rheumatoid arthritis is an autoimmune disease, which means the body’s immune system mistakenly attacks healthy tissue.

Autoimmune diseases occur when the immune system fails to recognize the body’s own molecules as “self,” or belonging to the person. Instead, it attacks body cells as though they were dangerous pathogens. There are more than 80 known autoimmune diseases. Recall that regulatory T cells help regulate the immune system. When autoimmune disorders occur, these regulatory T cells fail in their function. This results in damage to various organs and tissues.

The type of autoimmune disorder depends on the type of body tissue that is affected. These diseases cannot be cured, although they can be treated to relieve symptoms and prevent some of the long-term damage they cause. Why does the immune system attack body cells? In some cases, it’s because of exposure to pathogens that have antigens similar to the body’s own molecules. When this happens, the immune system not only attacks the pathogens, it also attacks body cells with the similar molecules.

• Autoimmune diseases occur when the immune system fails to distinguish self from non-self. As a result, the immune system attacks the body’s own cells.


About Human Biology

The Human Biology chapter provides an overview of the physiology of humans, from the skin inward. In addition to the skin, the skeletal, muscular, nervous, endocrine, circulatory, respiratory, digestive, excretory, immune, and reproductive systems are described.Many people have compared the human body to a machine. Think about some common machines, such as drills and washing machines. Each machine consists of many parts, and each part does a specific job, yet all the parts work together to perform an overall function. - Douglas Wilkin, Ph.D. & Jean Brainard, Ph.D.

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