Functions and Classification of Bone Tissue

Study Notes

Functions of Bone Tissue

Supports soft tissues and provides muscle attachment sites, acting as the body's structural framework.
Protects vital internal organs with bony encasements.
Assists in movement through the work of skeletal muscles.
Maintains mineral homeostasis by storing and releasing minerals, primarily calcium and phosphorus.
Facilitates blood cell production, known as hemopoiesis, occurring in red marrow.
Serves as a triglyceride storage site in the yellow marrow of adults.

Classification of Bones

Long bones: Shaft with two ends; examples include femur (thigh) and humerus (upper arm).
Short bones: Cube-like structure; wrist bones (carpals) and ankle bones (tarsals) are examples.
Flat bones: Thin and curved; includes skull bones and ribs.
Irregular bones: Do not fit into other categories; examples include vertebrae.

Major Features of a Long Bone

Diaphysis: Shaft of the long bone.
Epiphyses: Ends of the bone.
Metaphyses: Region between epiphysis and diaphysis, includes epiphyseal plate in growing bones.
Articular Cartilage: Hyaline cartilage at bone ends, reducing friction and absorbing shock at joints.
Periosteum: Connective tissue covering the bone, protecting it and aiding in repair and nourishment.
Medullary Cavity: Inner space of the diaphysis containing marrow.
Yellow Marrow: Area for fat storage.
Red Marrow: Site for blood cell production.
Endosteum: Lining of the medullary cavity.

Microscopic Structures of Bone

Bone tissue consists of cells widely separated by a significant matrix.
Types of bone cells:
- Osteogenics: Precursor cells for bone formation.
- Osteoblasts: Bone-building cells.
- Osteocytes: Mature bone cells, crucial for maintaining bone tissue.
- Osteoclasts: Cells derived from monocytes that break down bone tissue.
Bone matrix contains inorganic salts, primarily hydroxyapatite, calcium carbonate, and collagen fibers, important for bone hardness and tensile strength.
Calcification occurs in the presence of collagen fibers.

Haversian System in Compact Bone

Compact bone is organized into osteons (Haversian systems) that house blood vessels, lymphatic vessels, nerves, and osteocytes.
Osteons are aligned along lines of stress, which can shift with changes in mechanical stress on the bone.

Spongy Bone and Trabeculae

Spongy (cancellous) bone lacks osteons and is composed of trabeculae (bone columns or beams) that create spaces filled with red marrow.
Forms the internal structure of short, flat, irregular bones, and epiphyses of long bones.
Provides lightness while supporting and protecting red bone marrow.

Ossification

Ossification (or osteogenesis) refers to the formation of bone, starting with mesenchymal cells forming a template.

Endochondral Ossification

Involves bone formation from hyaline cartilage models, replacing cartilage with bone, essential for forming most body bones.

Intramembranous Ossification

Formation of bone directly from mesenchymal tissue, typically resulting in flat bones such as those of the skull and clavicles.

Description

Explore the essential functions of bone tissue, including support, protection, and movement. Learn about the classification of bones into long, short, flat, and irregular types, and discover the major features of long bones. This quiz tests your knowledge on the structural and functional aspects of bones.