Skeletal Connective Tissue: Cartilage and Bone

Vocabulary flashcards covering key concepts, tissue structure, cell types, growth patterns, diseases, and remodelling processes of cartilage and bone based on Lecture 5.

Perichondrium

The membrane surrounding semi-rigid dense cartilage tissue that contains blood vessels and nerves.

Chondrocytes

Mature cartilage cells that reside within lacunae and synthesize ground substance and matrix.

Lacunae

Hollow spaces or cavities within the extracellular matrix that contain chondrocytes.

Chondroblasts

Immature cartilage cells that differentiate from mesenchymal cells and actively synthesize matrix and ground substance.

Appositional Growth

Growth process that increases cartilage width (thickness) by adding new cartilage at the surface from the perichondrium.

Interstitial Growth

Growth process that increases cartilage length (longitudinal growth) from within through mitotic division of chondrocytes within their lacunae.

Hyaline Cartilage

The most abundant, glassy cartilage type that provides support through flexibility; found in articular cartilages, costal cartilage, larynx, trachea, and nose.

Elastic Cartilage

Cartilage containing an abundance of elastic fibers that tolerates repeated bending; located in the external ear and epiglottis.

Fibrocartilage

Intermediate cartilage type between hyaline and elastic cartilage that resists strong compression and tension; found in intervertebral discs and the pubic symphysis.

Cortical Bone

Dense, compact outer shell of bone accounting for $≈ 80\%$ of skeletal mass that provides mechanical strength, protection, and bending resistance.

Cancellous Bone

Porous, lattice-like network of trabeculae accounting for $≈ 20\%$ of skeletal mass that reduces bone weight, distributes forces, and contains bone marrow.

Osteoid

Unmineralized organic bone matrix ($20\%$ of total matrix) synthesized by osteoblasts, composed of $90\%$ Type I collagen fibers, glycosaminoglycans, and proteoglycans.

Osteoprogenitor Cells

Stem cells of bone tissue that give rise to osteoblasts and osteocytes.

Osteoblasts

Immature bone-forming cells rich in rough ER that synthesize collagen, secrete osteoid, and release vesicles of alkaline phosphatase for matrix mineralization.

Osteocytes

Inactive osteoblasts embedded in bone matrix, representing the most abundant cell type found in mature bone.

Osteoclasts

Large multi-nucleated phagocytic cells in bone that resorb and erode bone tissue by secreting organic acids and lysosomal proteolytic enzymes.

Diaphysis

The shaft of a long bone consisting of a marrow cavity enclosed by compact bone.

Epiphysis

The expanded end of a long bone, mainly composed of spongy bone covered by a thin outer layer of compact bone.

Metaphysis

The flared region of a long bone located between the diaphysis and epiphysis.

Epiphyseal Plate

Cartilage boundary separating the epiphyseal and diaphyseal cavities that maintains the longitudinal growth process.

Woven Bone

Immature, nonlamellar bone tissue containing randomly arranged collagen fibers and high ground substance density, formed during fetal life or initial fracture repair.

Lamellar Bone

Mature adult bone tissue featuring parallel, regular sheets of collagen fibers that replace woven bone.

Intramembranous Ossification

Direct bone formation process where osteoblasts lay down bone without a prior cartilage precursor, typical of flat bones like the skull and sternum.

Endochondral Ossification

Bone formation process involving a cartilage model precursor, responsible for long bone formation and standard fracture repair.

Bone Remodelling Cycle

A 5-phase sequence (Activation, Resorption, Reversal, Formation and mineralization, Quiescence) that replaces $≈ 10\%$ of adult bone per year.

Polychondritis

A condition characterized by inflammation and degeneration of cartilage.

Chondromalacia

Degeneration of joint cartilage, commonly occurring in the knees.

Costochondritis

Inflammation of rib cartilage causing chest pain.

Tietze's Syndrome

Inflammation of the cartilage that connects the ribs to the breastbone.

Cortisol (Bone Regulation)

Hormone that induces bone loss by promoting osteoblast death (apoptosis).

Parathyroid Hormone (PTH)

Hormone that causes bone loss by activating osteoclast activity.