Cartilage Jelly-like matrix(chrondroitin sulfate) containing collagen and elastic fibers and chondrocytes surrounded by perichondrium

Avascular except in perichondrium Strength = collagen Resilience = chondroitin sulfate Chondrocytes occur within spaces called lacunae

Pericondrium Dense irregularly arranged connective tissue (type I collagen) Ensheaths cartilage Has blood vessels that nourish chondrocytes

Chondroblast Progenitor of chondroblast Lines border bwteen pericondrium and matrix Secretes type II collagen and other ECM components

Chondrocytes Mature cartilage cell Resides in space called lacuna Clear areas= golgi and lipid droplets Chondrocytes completely fill lacunae ReR and euchromatic nuclei Active, secret matrix

Matrix of cartilage Rigidity, elatsicility, resilience Fibers = collagen and elastic Ground substance = GAGs, proteoglycans, water, basophilic,

territorial matrix high in sulfated proteoglycansCartilage growth Interstitial

AppositionalInterstitial growth Increasing in length, chondrocyte divide and secrete matrix

from within lacunaeAppositional growth Increasing in width, chondrocytes deposit matrix on pre-existing

cartilageTypes of cartilage Hyaline cartilage

Eslastic cartilage Fibroud cartilage

Hyaline cartilage Function= bone development, support tisuue and organs Matrix = type II collagen, chrondoitin, keratin, hyaluronic acid,

water Location = tracheal rings, nasal septum, larynx, articular

surfaces of jointsElastic cartilage Function = flexibility

Matrix = elastic fibers+hyaline matrix Location = external ear, auditory tubes, epiglottis Stain = black with Weigart’s stain

Fibrocartilage Function = support w/ great tensile strength Matrix = type I collagen, oriented to stress plane Location = intervertebral disc, pubic symphysis, menisci of knee Chondrocytes align between collagen fibers Fibers align to planes of stress

Function of bone Support for soft tissues Sites of attachment of muscles and tendons essential for

locomotion Protects vital organs or cranium and other body cavities Enclose blood-forming elements in bone marrow Storage of calcium and phosphate

Cells of bones Osteoblasts Osteocytes Osteoclasts

Fibers Type I collagenGround substance GAGs : hyaluronan, chondroitin, keratin

Proteoglycans : short core protein, fewer GAG chains than cartilage

Hydroxyapatite crystals : calcium phosphateCartilage Water content = 70%

Collagen II = 40% organic content Grows interstitally and apoositionally Avascular

Bone Water content = 25% Collegen I = 90% organic content Other ground substance = osteonecton, osteopontin,

osteocalcin Grows by apposition Highly vascular

Osteonectin Collagen to bone mineralOsteocalcin Calcium binding protein involved in bone calcificationOsteopontin Osteoblast and osteoclasts to boneCells of bone Osteoclast

Osteoblast Osteocyte

Osteoblast Actively mitotic bone cell Secrete matrix to surround them

Osteocyte Mature bone cell, in lacunaeOsteoc;ast Related to macrophages

Secret HCl to break down calcium and phosphorusCompact bone Dense, outer layer, diaphysisSpongy bone Inyternal ,spongy layer, epiphysisMicroscopical examination compact bone

Functional unit = osteon (Haversian system) Core of osteon = central canal (Haversian canal), contain blood

supply to bone cells Within osteon = osteocytes, resides in lacunae Thin tubes called canaliculi between lacuna and nearby

capillaries Rings called lamellae

Microscopic examination spongy bone

Honeycomb of small needle –like pieces called trabeculae Open spaces of trabeculae are filled with red and yellow

marrow Each trabeculae = several types of lamellae and osteocytes in

lacunae, no osteon too small