Rheumatoid arthritis - causes, symptoms, diagnosis, treatment, pathology

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In rheumatoid arthritis, “arthr-“ refers to joints, “-itis” means inflammation,

and “rheumatoid” comes from rheumatism, which more broadly refers to a musculoskeletal

illness.

So, rheumatoid arthritis is a chronic, inflammatory disorder that mostly affects the joints, but

can also involve other organ systems like the skin and lungs as well.

Alright, so a healthy joint typically has two bones covered with articular cartilage

at the ends.

Articular cartilage is a type of connective tissue that acts like a protective cushion

- a lubricated surface for bones to smoothly glide against.

One type of joint, like the knee joint is called a synovial joint.

A synovial joint connects two bones with a fibrous joint capsule that is continuous with

the periosteum or outer layer of both bones.

The fibrous capsule is lined with a synovial membrane that has cells that produce synovial

fluid and remove debris.

The synovial fluid is normally a viscous fluid like the jelly-like part of a chicken egg

and it helps lubricate the joint.

To help serve these synovial cells, the synovial membrane also has blood vessels and lymphatics

running through it.

Together, the synovial membrane and the articular cartilage form the inner lining of the joint

space.

Rheumatoid arthritis is an autoimmune process that is typically triggered by an interaction

between a genetic factor and the environment.

For example, a person with a certain gene for an immune protein like human leukocyte

antigen, or HLA- DR1 and HLA–DR4, might develop rheumatoid arthritis after getting

exposed to something in the environment like cigarette smoke or a specific pathogen like