Cartilage and Bone Lecture Vocabulary

Vocabulary flashcards covering key terms, cell types, structures, and functions related to cartilage and bone from the provided lecture notes.

Cartilage

Tough, durable supporting connective tissue with an ECM rich in GAGs, proteoglycans, and collagen/elastic fibers that provides mechanical and protective functions.

Chondrocyte

Mature cartilage cell residing in a lacuna; maintains cartilage ECM.

Lacuna (cartilage)

Matrix cavity that houses a chondrocyte.

Perichondrium

Dense connective-tissue sheath surrounding most cartilage (absent on articular cartilage); outer fibrous layer + inner chondrogenic layer with stem cells.

Chondroblast

Cartilage-forming cell derived from mesenchyme that secretes ECM and matures into a chondrocyte.

Isogenous Group

Cluster of chondrocytes in one lacuna produced by mitotic division of a single chondrocyte.

Hyaline Cartilage

Most common cartilage; type II collagen–rich, glassy matrix; found in articular surfaces, respiratory passages, ventral ribs, and epiphyseal plates.

Elastic Cartilage

Cartilage resembling hyaline but with abundant elastic fibers; present in ear auricle, epiglottis, Eustachian tube, etc.

Fibrocartilage

Mixture of hyaline cartilage and dense connective tissue; type I & II collagen; no perichondrium; provides tough cushioning (e.g., intervertebral discs, pubic symphysis).

Aggrecan

Major cartilage proteoglycan that binds hyaluronan to create highly hydrated ECM.

Type II Collagen

Primary fibrillar collagen of cartilage matrix providing tensile strength.

Osteoarthritis

Degenerative joint disease caused by gradual loss or altered properties of articular hyaline cartilage.

Bone

Specialized connective tissue composed of calcified matrix plus osteocytes, osteoblasts, and osteoclasts; provides support, protection, mineral reservoir, and lever system.

Osteoblast

Bone-forming cell derived from mesenchyme; secretes osteoid (type I collagen & matrix proteins) and initiates mineralization.

Osteoid

Unmineralized organic bone matrix secreted by osteoblasts.

Osteocyte

Mature bone cell enclosed in a lacuna; maintains mineralized matrix and senses mechanical stress via canaliculi processes.

Canaliculi

Tiny channels in bone matrix that house osteocyte processes, enabling nutrient and signal exchange.

Osteoclast

Large multinucleated cell from monocyte fusion that resorbs bone by creating a sealing zone and ruffled border.

Sealing Zone

Ring-shaped area where an osteoclast tightly adheres to bone, isolating the resorption compartment.

Ruffled Border

Highly folded plasma membrane of an active osteoclast facing bone surface; site of acid and enzyme release.

Bone Matrix

50 % inorganic (mainly hydroxyapatite) + 50 % organic (type I collagen, proteoglycans, glycoproteins) providing hardness and resilience.

Hydroxyapatite

Crystalline calcium phosphate salt that gives bone its compressive strength.

Osteonectin

Matricellular glycoprotein linking collagen and minerals in bone matrix.

Periosteum

Outer fibrous + inner cellular layer covering bone surface; contains fibroblasts, blood vessels, and osteoprogenitor cells.

Endosteum

Delicate connective tissue lining internal bone surfaces and trabeculae; contains osteogenic and bone-lining cells.

Osteoprogenitor Cell

Mesenchymal stem cell in periosteum/endosteum that can differentiate into osteoblasts.

Bone Lining Cell

Flattened inactive osteoblast covering quiescent bone surfaces.

Compact (Cortical) Bone

Dense outer bone; forms 80 % of skeletal mass.

Cancellous (Trabecular) Bone

Spongy interior bone with interconnecting trabeculae; 20 % of bone mass.

Lamellar Bone

Mature bone with parallel or concentric layers (lamellae) of calcified matrix with alternating collagen orientation.

Osteon (Haversian System)

Structural unit of compact bone: concentric lamellae surrounding a central canal.

Central (Haversian) Canal

Channel at osteon center containing blood vessels, nerves, and endosteum.

Volkmann Canal

Transverse perforating canal connecting adjacent osteons and their vessels.

Interstitial Lamellae

Remnants of old osteons found between intact osteons after remodeling.

Cement Line

Outer boundary of an osteon, marking limit of bone remodeling unit.

Woven Bone

Immature, nonlamellar bone with randomly arranged type I collagen; first to form in development or fracture repair.

Epiphyseal Plate

Hyaline cartilage growth plate at long bone ends responsible for longitudinal growth.

Shock Absorber (Fibrocartilage Function)

Fibrocartilage’s role in cushioning compressive forces, e.g., intervertebral discs.

Type I Collagen

Dominant collagen in bone matrix and dense connective tissue, providing tensile strength.

Mesenchymal Stem Cell

Multipotent progenitor giving rise to chondroblasts, osteoblasts, and other connective-tissue cells.

Functions of Bone

Support, organ protection, lever for movement, hematopoiesis in marrow, and mineral reservoir (Ca²⁺, PO₄³⁻).