University:
Franklin University
Course:
BIO-251 | General Anatomy/Physiology I
Academic year:

2019
Views:

468

Pages:

42
Author:

NovaNurturer

Definition Cartilage is a specialized type of dense connective tissue designed to give support, bear weight and withstand tension, torsion and bending. cartilage forms a framework of supporting for softer tissue. It is smooth & lubricant surface in movement joint. Bearing mechanical stresses without permanent distortion. General Features • Cartilage support regions of the body that require flexibility Non nervous structure All of types Cartilage are avascular Poor regeneration capacity Usually surrounded by perichondrium (except articular cartilage and fibro cartilage) Overview of Cartilage • Shock-absorbing because it is resilient. • Smooth surface allows sliding against it, in movement goings • Essential for growth, development of bone. Components Cells Chodroblast Chondrocytes Matrix • Fibers • Collagen 2 fibril • Elastic fibers • Ground substance •Tissue fluid •GAGs & proteoglycans Pluripotent mesenchymal cell Chondroblast Muscle cell Adipocyte Osteoblast Cbfa1 Osteocalcin Fibroblast Chondrogenesis Cartilage, formation and growth Cells • (Chondrocyte) • (Chondroblast) Perichondrial fibroblast Perichondrium Chondroblast Cartilage Interterritorial matrix Chondrocyte chondrocyte Territorial matrix Origin: mesenchimal cells Function:depend on balance of hormonal changes • Thyroxin, growth H, testosterone = + Estradiol, chortisone = - Perichondral Fibroblast Outer surface: elipsoid chondrocyte Perichondinum • Inner surface:round chondrocyte Chondroblast Cartage Intertentional Chondrocyte Territorial matrix The Extracellular Matrix connective tissue 1- Glycosaminoglycans (GAGs). Hyaluronans Chondroitin sulfates Heparan sulfates (including heparin) Keratan sulfates. 2- Proteoglycans. GAGs bind to core proteins. e.g. aggrecan in cartilage. 3- GP 12 Proteoglycan: Proteoglycan is the compound of GAGs and core protein (Shown as the fig above). Aggrecan Keratan sullato (glycosaminoglycan) Chondroitin sullate (glycosaminoglycan) Proteoglycans Hyaluronan molecule Linker protein Core protain Proteoglycan aggregate Proteoglycans are extracellular protein complexes of glycosaminoglycans Proteoglycan aggregates are formed by: 1. An axial hyaluronan molecule. 2. Core proteins attached to the hyaluronan molecule by a linker protein 3. Glycosaminoglycans attached to a core protein. Several chains of glycosaminoglycans bound to the core protein form a proteoglycan, The molecular mass of a proteoglycan is about 10 kd. Elsevier. Kierszenbaurn: Histology and Cell Biology: An Introduction to Pathology 2e www.studentconsult.com The physical property of cartilage depend on electrostatic bond between collagen 2 fibril and sulfated GAGs on Proteoglycan Hyaluronic acid Proteoglycan Perichondrium Perichondrial fibroblast Chondroblast Type collagen fibril Hyaluronic acid Link protein Core protein Chondroitin sulfate Collagen (type II Cartilage Interterritorial marix Chondrocyte Territorial matrix • Dense connective tissue Perichondrium • Like capsule surrounds glands and organs • Source of new cartilage cells Perichondrial fibroblast Perichondrium Chondroblast Cartilage Interterritorial matrix Chondrocyte Territorial matrix Perichondrium 1- Inner cellular laver Chondrogenic layer give rise to cartilage (appositional growth) 2. Outer fibrous layer Fibroblast layer Perichondrium No perichondrium regions: Articular surface of joints fibrocartilage Perichondrium Seen under microscope Fibrous perichondrium Chondrogenic perichondrium Isogenic groups 17 Cartilage matrix Endochondral ossification Chondrocytes Matrix produce and maintain Singular Cluster (Isogenous group) Depended on cell activity Active Chondrocytes: matrix G M N G M RER Golgi Secretory granules Vesicles Intermediate filament Microtubules Actin microfilament. Lipid droplets and glycogen stores FER