What is Rheumatoid Arthritis?

Rheumatoid Arthritis (RA) is an autoimmune disease. The immune system normally identifies and destroys foreign substances in the body, such as viruses and bacteria; in an autoimmune disease, the immune system mistakes the body's own cells for invaders. In RA, the immune system attacks the synovia, the membranes lining the joints. This causes swelling, stiffness, and pain and can eventually damage bones, tendons, and cartilage, causing deformities and limiting motion. Rheumatoid arthritis can also affect other parts of the body, including the heart, lungs and salivary and tear glands.