Cartilage and Bone

Characteristics of Cartilage

semirigid, flexible yet resilient due to elastic fibers, collagen fibers, and a gel-like ground substance, avascular

Functions of cartilage

support soft tissues, articular surfaces for joints, provide a model for endochondral bone formation

Chondroblasts

cells that produce cartilage matrix and are essential for cartilage growth and repair.

Chondrocytes

the mature cells of cartilage that maintain the cartilage matrix.

Extracellular Matrix of cartilage

protein fibers embedded in a gel-like ground substance

perichondrium

dense irregular connective tissue

Types of cartilage

hyaline (flexible but resilient), fibrocartilage (contains thick collagen fibers, shock absorber), elastic (contains elastic fibers, provides flexibility)

Organic component of bone matrix

Called osteoid and contains collagen and other proteins

Inorganic component of bone matrix

called hydroxyapatite and contains calcium phosphate and calcium hydroxide

Classification by structure of bones

long, short, flat, irregular, and sesamoid

Structure of flat bones

compact/cortical bone (lined by periosteum and composed of osteons)

spongy/cancellous bone (lined by endosteum, composed of trabeculae, often contains red bone marrow)

Osteocyte

a mature bone cell that maintains the bone matrix and communicates with other bone cells through canaliculi.

Osteoblast

a bone-forming cell responsible for the synthesis of the bone matrix and aids in mineralization.

Osteogenic cell

a stem cell that differentiates into osteoblasts and is involved in bone formation.

Osteoclast

a large multinucleated cell that breaks down bone tissue, playing a crucial role in bone remodeling.

Structure of compact bone

Ossification

the process of bone tissue formation, where cartilage is gradually replaced by bone.

Intramembranous Ossification

bone growth within a membrane. Form flat bones of skull, some facial, mandible, and clavicle

Endrochondral Ossification

Bone growth within cartilage, turns fetal framework of hyaline cartilage into bone, formation of most bones

Osteomalacia (rickets)

a disorder characterized by the softening of bones due to a deficiency of vitamin D, calcium, or phosphate, leading to weakened bones and increased fracture risk.

Osteoporosis

Excessive bone resorption, aged and post-menopause