Overview
This lecture reviews the microscopic structure of osseous (bone) tissue, focusing on its features as connective tissue and the unique arrangements found in bone.
Structural Features of Osseous Tissue
- Osseous tissue is the primary tissue composing bones.
- Under the microscope, bone shows circular patterns called osteons, which are the structural units of hard bone.
- Each osteon contains several distinct features important for bone function and structure.
Components of an Osteon
- Osteocytes are bone cells found in small spaces called lacunae, arranged in rings around the osteon.
- The central canal (Haversian canal) is located at the center of each osteon and houses blood vessels and nerves.
- Canaliculi are microscopic cracks radiating from the central canal to osteocytes, allowing nutrient and gas diffusion.
- Lamellae are concentric rings of osteocytes and lacunae found within each osteon.
Connective Tissue Characteristics
- Osseous tissue qualifies as connective tissue by containing cells (osteocytes), fibers (mainly collagen), and an extracellular matrix.
- The hardness and density of bone come from mineral deposits combined with collagen fibers in the matrix.
Key Terms & Definitions
- Osseous tissue â the main tissue making up bones.
- Osteon â the structural unit of compact bone, visible as circular patterns.
- Osteocyte â a bone cell residing in a lacuna within bone tissue.
- Lacuna (plural: lacunae) â small cavities in bone containing osteocytes.
- Central canal (Haversian canal) â central space in each osteon for blood vessels and nerves.
- Canaliculus (plural: canaliculi) â tiny channels connecting osteocytes to the central canal.
- Lamella (plural: lamellae) â concentric rings of bone matrix within an osteon.
- Collagen fibers â provide strength and flexibility to bone; found in the matrix.
- Extracellular matrix â non-cellular part of tissue providing structural support, containing collagen and minerals.
Action Items / Next Steps
- Review the structure and function of osteons and their components.
- Be prepared to identify bone features (osteon, osteocyte, lacuna, canaliculi, lamellae) on microscope slides for upcoming assessments.