Question

Describe the Haversian system

Answer 1

The 'Haversian system' gets its name from an English physician named Clopton Havers (1657-1702), who is known for his seminal research in the analysis of the microscopic structure of bones and joints. He was the first person to describe Sharpey's fibers.

The terms 'osteoblasts', 'osteocytes', and 'osteoclasts' refer to three types of specialized bone cells. An osteoblast is a bone-forming cell that secretes several layers of a bone matrix material called osteoid. Osteoid is composed of collagen and mucopolysaccharide. After the osteoid layers are laid down, inorganic salts get deposited in the layers, thereby forming hardened, mineralized bone. The osteoblasts then turn into mature bone cells called osteocytes, when a new bone is being formed. Osteocytes get embedded within the bone matrix, and help maintain the structure of the bone. Osteoclasts are cells that help break down bone, after which osteoblasts help in the formation of a new bone. This process helps maintain the calcium levels. Compact bone and spongy/cancellous bone are the two types of bones in the human body. The former makes up about 80% of the bones of the human body, while the latter constitutes the remaining 20%. The compact bones form the hard exterior of the bones, whereas the spongy bones have several pores that are filled with nerves and blood vessels. The terms 'Haversian system' or 'osteon' refer to the basic cylindrical-shaped structural unit of a compact bone, which in turn forms a substantial part of the structure of the long bones of the human body. The osteons are closely packed, with osteocytes lined up in concentric rings. This imparts a hard and dense texture to the compact bones.