Answer
In a given osteon (also known as a Haversian system), the lamellae immediately adjacent to the central canal, known as the central lamellae, are the oldest. The central lamellae are the first to be deposited during the process of bone formation and remodeling. Here's an explanation for why this is the case:
1. **Osteon Formation:** Osteons are the structural units of compact bone tissue and are formed through a process called osteogenesis or bone remodeling. The central canal, also known as the Haversian canal, contains blood vessels and nerves and is essential for the nutrient supply to bone cells.
2. **Lamellar Deposition:** Bone tissue is constantly undergoing remodeling, a dynamic process in which old bone is resorbed (broken down) by osteoclasts, and new bone is formed by osteoblasts. During the initial formation of an osteon, osteoblasts secrete collagen fibers and other organic matrix materials, which form the central lamellae. These central lamellae are rich in collagen and are the foundation upon which the entire osteon is built.
3. **Concentric Lamellae:** As bone remodeling continues, subsequent layers of lamellae are added concentrically around the central canal. These newer lamellae, known as concentric lamellae, are added on top of the central lamellae, making them progressively younger as you move outward from the central canal. They contain both organic matrix and minerals like hydroxyapatite, making the bone stronger and more mineralized.
4. **Maturation:** Over time, as bone undergoes repeated cycles of remodeling, additional concentric lamellae are added, and the osteon matures. This results in a layered structure with the central lamellae being the oldest and the outer concentric lamellae being the most recently formed.
In summary, the central lamellae are the oldest because they are the first to be deposited during the initial formation of an osteon by osteoblasts. As bone remodeling continues, newer concentric lamellae are added around the central canal, making them progressively younger as you move outward within the osteon. This arrangement allows bone tissue to be both strong and adaptable to changing mechanical stresses.
Work Step by Step
In a given osteon (also known as a Haversian system), the lamellae immediately adjacent to the central canal, known as the central lamellae, are the oldest. The central lamellae are the first to be deposited during the process of bone formation and remodeling. Here's an explanation for why this is the case:
1. **Osteon Formation:** Osteons are the structural units of compact bone tissue and are formed through a process called osteogenesis or bone remodeling. The central canal, also known as the Haversian canal, contains blood vessels and nerves and is essential for the nutrient supply to bone cells.
2. **Lamellar Deposition:** Bone tissue is constantly undergoing remodeling, a dynamic process in which old bone is resorbed (broken down) by osteoclasts, and new bone is formed by osteoblasts. During the initial formation of an osteon, osteoblasts secrete collagen fibers and other organic matrix materials, which form the central lamellae. These central lamellae are rich in collagen and are the foundation upon which the entire osteon is built.
3. **Concentric Lamellae:** As bone remodeling continues, subsequent layers of lamellae are added concentrically around the central canal. These newer lamellae, known as concentric lamellae, are added on top of the central lamellae, making them progressively younger as you move outward from the central canal. They contain both organic matrix and minerals like hydroxyapatite, making the bone stronger and more mineralized.
4. **Maturation:** Over time, as bone undergoes repeated cycles of remodeling, additional concentric lamellae are added, and the osteon matures. This results in a layered structure with the central lamellae being the oldest and the outer concentric lamellae being the most recently formed.
In summary, the central lamellae are the oldest because they are the first to be deposited during the initial formation of an osteon by osteoblasts. As bone remodeling continues, newer concentric lamellae are added around the central canal, making them progressively younger as you move outward within the osteon. This arrangement allows bone tissue to be both strong and adaptable to changing mechanical stresses.
