Rheumatoid Arthritis - Introduction

Introduction

Rheumatoid arthritis (RA) is a chronic disease in which various joints in the body are inflamed, leading to swelling, pain, stiffness, and the possible loss of function.

The process may develop in the following way:

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• The disease process leading to rheumatoid arthritis begins in the synovium, the membrane that surrounds a joint and creates a protective sac.
• This sac is filled with lubricating liquid called the synovial fluid. In addition to cushioning joints, this fluid supplies nutrients and oxygen to cartilage, a slippery tissue that coats the ends of bones.
• Cartilage is composed primarily of collagen, the structural protein in the body, which forms a mesh to give support and flexibility to joints.
• In rheumatoid arthritis, an abnormal immune system response produces destructive molecules that cause continuous inflammation of the synovium. Collagen is gradually destroyed, narrowing the joint space and eventually damaging bone.
• If the disease develops into a form called progressive rheumatoid arthritis, destruction to the cartilage accelerates. Fluid and immune system cells accumulate in the synovium to produce a pannus, a growth composed of thickened synovial tissue.
• The pannus produces more enzymes that destroy nearby cartilage, aggravating the area and attracting more inflammatory white cells, thereby perpetuating the process.

This inflammatory process not only affects cartilage and bones but can also harm organs in other parts of the body.

Click the icon to see an image of rheumatoid arthritis.

Review Date: 02/16/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).