Bone Health Quiz

Overview of Bone Structure and Non-Neoplastic Bone Diseases

• Bone is composed of an acellular portion (matrix) and a cellular portion (osteoblasts, osteocytes, and osteoclasts).
• Spongy bone consists of trabeculae that form a loose bony framework, and bone marrow is located between the trabeculae.
• Compact bone is denser and contains Haversian systems, which transmit blood vessels to spongy bone.
• Osteoclasts secrete acidic substances that resorb bone, and their function is regulated by RANK, RANKL, osteoprotegerin, and M-CSF.
• Osteoporosis is a decrease in bone mass that can result from genetic factors, physical activity, stresses on bone, and nutritional factors.
• Postmenopausal females have reduced levels of estrogen, which results in less inhibition of IL6 and RANKL and makes sex hormones osteoprotective.
• Primary osteoporosis is senile, while secondary osteoporosis results from underlying diseases that decrease bone mass.
• The entire skeleton is affected by osteoporosis, but weight-bearing areas are prone to fracturing.
• Paget's disease of bone is characterized by the production of physiologically unstable bone due to osteogenic-osteolytic imbalance.
• Paget's disease usually affects patients over 70 years old and can involve any bone, most commonly the pelvic ileum, lumbosacral spine, femur, tibia, and skull.
• Paget's disease has three phases: osteolytic, mixed, and osteosclerotic.
• In the mixed and osteosclerotic phases, osteoblasts form unstable bone due to "jigsaw pattern" bone deposition, which is unstable and greatly prone to fracturing.