Final answer:
Rheumatoid arthritis primarily affects the synovial joints of the hands, feet, and cervical spine. The cause of RA is unknown, but it is an autoimmune disease in which the body's immune system attacks healthy tissue. RA is more common in women and usually starts between ages 40-50.
Step-by-step explanation:
Rheumatoid arthritis (RA) is an inflammatory disorder that primarily affects the synovial joints of the hands, feet, and cervical spine. Affected joints become swollen, stiff, and painful. Although it is known that RA is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue, the cause of RA remains unknown. Immune cells from the blood enter joints and the synovium causing cartilage breakdown, swelling, and inflammation of the joint lining. Breakdown of cartilage causes bones to rub against each other causing pain. RA is more common in women than men and the age of onset is usually 40-50 years of age.