A&P: Skeletal System - Bone Tissue Flashcards

Introduction to Bone Tissue

• Bone consists of various connective tissues: bone, cartilage, dense connective tissue, epithelium, blood-forming tissues, adipose tissue, and nervous tissue.
• Each bone is classified as an organ; together, bones and cartilage form the skeletal system.

Functions of Bones

• Support: Bones provide structural framework for the body, supporting soft tissues and offering muscle attachment sites.
• Protection: Bones encase and protect vital internal organs from injury.
• Movement: Bones work with skeletal muscles to facilitate body movements.
• Mineral Storage: Act as a reservoir for minerals, particularly calcium and phosphorus, aiding in mineral homeostasis.
• Hematopoiesis: Blood cell formation occurs within the red marrow of bones.
• Energy Storage: Adipose yellow marrow in adult bones serves as a triglyceride storage site.

Histology of Bone Tissue

• Bone tissue, or osseous tissue, features widely separated cells embedded in extensive matrix.

Types of Bone Cells

• Osteogenic Cells: Stem cells that develop into osteoblasts, found in the endosteum and periosteum.
• Osteoblasts: Bone-building cells that secrete collagen and other organic components to form the matrix.
• Osteocytes: Mature bone cells that reside in the matrix, crucial for maintaining bone tissue.
• Osteoclasts: Derived from white blood cells, they secrete acids and enzymes to break down bone tissue (osteolysis).

Bone Matrix

• Composed of inorganic salts (mainly calcium phosphate) and collagen fibers.
• Calcification or mineralization occurs in the presence of collagen fibers, providing hardness and tensile strength to bones.

Bone Structure

• Compact Bone (80%): Structured in osteons or Haversian systems, which contain blood vessels, nerves, and osteocytes; aligned along stress lines.
• Spongy Bone (20%): Lacks osteons; consists of trabeculae surrounding red marrow spaces, providing lightweight support and protection for red bone marrow.

Components of a Long Bone

• Bone structure includes several parts: diaphysis, epiphyses, metaphyses, epiphyseal plate, hyaline cartilage, periosteum, marrow cavity, and endosteum.

Specific Bone Features

• Diaphysis: The shaft of a long bone.
• Epiphyses: The ends of a long bone.
• Metaphyses: The transitioning regions between epiphysis and diaphysis.
• Epiphyseal Plate: Growth area in developing bones.
• Hyaline Cartilage: Reduces friction and absorbs shock at joints.
• Periosteum: Connective tissue covering that protects bone, aids in repair, and serves as an attachment point for tendons and ligaments.
• Marrow (Medullary) Cavity: Central space in the diaphysis containing fatty yellow bone marrow.
• Endosteum: Lining of the marrow cavity containing osteogenic cells.

Blood Supply in Bone

• Periosteal Arteries: Supply outer compact bone through Volkmann's canals, connecting with various vessels.