Bone Health and Rheumatoid Arthritis

A set of flashcards covering key concepts from the lecture on bone health and rheumatoid arthritis.

What are the primary roles of osteoclasts in bone health?

Osteoclasts are multinucleated cells that resorb bone mineral and the collagenous matrix.

What are osteoblasts responsible for in bone formation?

Osteoblasts produce and deposit type I collagen and non-collagenous proteins, forming the bone matrix.

How are osteocytes related to osteoblasts?

Osteocytes are terminally differentiated osteoblasts embedded in the bone matrix.

What role does the RANKL/OPG system play in bone remodeling?

RANKL stimulates osteoclast formation while OPG acts as a decoy receptor to inhibit excessive osteoclast activity.

What is the significance of the balance between osteoclast and osteoblast activity?

The balance is crucial for maintaining bone mass; an imbalance leads to either bone loss or excessive bone formation.

What is focal bone erosion, and when does it occur in rheumatoid arthritis?

Focal bone erosion occurs within cortical bone at the junction of cartilage and bone, particularly in arthritic joints.

What is systemic osteoporosis in the context of rheumatoid arthritis?

Systemic osteoporosis refers to thinning of bone throughout the skeleton, often seen in patients with uncontrolled rheumatoid arthritis.

What are the systemic effects of cytokines like TNF, IL-1, and IL-6 in RA?

These cytokines promote osteoclast differentiation and contribute to bone destruction.

How do bisphosphonates work in treating bone loss in RA?

Bisphosphonates inhibit osteoclast activity, thus reducing bone resorption.

What is the role of osteocytes in bone remodeling?

Osteocytes regulate bone remodeling and maintain mineral homeostasis in response to mechanical loads.

What effect does denosumab have on osteoclasts?

Denosumab inhibits RANKL, blocking osteoclast formation and reducing bone erosion.

What are the consequences of excessive osteoclast activity?

Excessive osteoclast activity leads to increased bone resorption, loss of bone density, and higher fracture risk.

What triggers osteoclast differentiation?

Osteoclast differentiation is triggered by RANKL produced by osteoblast lineage cells and stimulated by pro-inflammatory cytokines.

What is the main structural component of bone?

Bone consists predominantly of collagen (type I) and mineralized matrix (hydroxyapatite).

How does the inflammatory environment in RA affect bone health?

The inflammatory environment leads to increased RANKL production, promoting osteoclast differentiation and bone loss.

What happens during the bone remodeling cycle?

The cycle includes phases of resorption, reversal, mineralization, and quiescence, enabling bone adaptation and renewal.

What defines juxta-articular osteopenia in RA?

Juxta-articular osteopenia is bone loss occurring near the affected joints, typically early in the disease.

What occurs during the mineralization phase of bone remodeling?

During mineralization, osteoblasts facilitate the deposition of minerals, hardening the osteoid tissue.

How do mechanical stresses affect bone remodeling?

Bone remodels in response to mechanical stresses; areas under stress will have increased bone deposition.

What is the relationship between physical activity and bone health?

Physical activity provides mechanical stimulus necessary for bone formation and maintenance of bone density.

What are non-collagenous proteins and their role in bone health?

Non-collagenous proteins regulate mineralization, attract cells during remodeling, and mediate the attachment of bone cells.