Alkaline phosphatase is an enzyme found in various tissues throughout the body, including the liver, bones, kidneys, and bile ducts, and plays a crucial role in breaking down proteins and facilitating phosphate transfer. Its levels in the blood can be indicative of bone or liver disorders, making it an important marker in diagnostic testing.
25-hydroxyvitamin D is a prehormone produced in the liver by hydroxylation of vitamin D3 and is the main circulating form used to assess vitamin D status in the body. It plays a critical role in calcium homeostasis and bone metabolism, and its deficiency can lead to conditions such as osteoporosis and rickets.
Receptor activator of nuclear factor kappa-B (RANK) is a crucial protein involved in the regulation of bone metabolism, immune response, and lymph node development by acting as a receptor for RANK ligand (RANKL). Its activation leads to osteoclast differentiation and activation, making it a target for therapeutic interventions in conditions like osteoporosis and cancer-induced bone diseases.
Nutrient arteries are crucial blood vessels that supply the long bones with the necessary nutrients and oxygen needed for growth and maintenance. They enter the bone through the nutrient foramen and branch out to provide the inner layers of the bone with essential resources for cellular functions and bone health.
Calcium-sensing receptors (CaSR) are G-protein coupled receptors that play a crucial role in maintaining calcium homeostasis by regulating parathyroid hormone secretion and renal calcium reabsorption. They are essential in various physiological processes, including bone metabolism, and have implications in disorders like hypercalcemia and hypocalcemia.
Periosteal circulation refers to the network of blood vessels that supply the periosteum, the dense layer of vascular connective tissue enveloping the bones. This circulation is crucial for bone growth, repair, and nourishment, playing a pivotal role in the healing process of fractures and the overall health of the skeletal system.
Parathyroid hormone-related peptide (PTHrP) is a protein that plays a crucial role in regulating calcium levels in the body, similar to parathyroid hormone (PTH), but it is also involved in a wide range of other physiological processes, including bone development and cellular growth. Its discovery has significantly advanced our understanding of hypercalcemia in cancer patients, as PTHrP is often overexpressed in various malignancies, leading to increased calcium levels.
Osteoimmunology is an interdisciplinary field that explores the complex interactions between the immune system and bone metabolism, showing that immune cells and cytokines have pivotal roles in bone health and disease. This field reveals novel insights into bone diseases like osteoporosis and rheumatoid arthritis, and holds promise for new therapeutic approaches targeting immune components to treat these conditions.