BIOL 2221 Lecture Notes - Lecture 6: Parathyroid Gland, Thyroid, Osteoporosis
Document Summary
Functions: support, protection, anchorage (anchoring for are muscles to help move), storage (calcium), formation of blood cells (red blood cells, white blood cells *immune system), hormone production (osteocalcin) Osteogenic cell- (stem cell) - when stem cells divide they create osteoblast. Osteoblast (build) - matrix- synthesizing cell responsible for bone growth; composed of minerals. Osteocytes (inside a lucunae) - mature bone cell that monitors and maintains the mineralized bone matrix. Cnaliculi-tiny tunnels that connect lucunae with osteocytes to other lucunae. Older cells are pushed down toward diaphysis: hypertonic zone. Older chondrocytes and lacunae enlarge: calcification zone. Cartilage matrix calcifies; chondrocytes die; blood vessels invade cavity: ossification zone. Calcified spicules eroded via osteoclast; new spongy bone forms via osteoblast activity. Unequal rates of: osteoblasts in periosteum (outside of long bone); osteoblasts in endosteum. Constant bone turnover (broken down and remade)- calcium in the bone stay stagnant they begin to clump up. Clumps cause bones to become more brittle *weakens bones.
