153 Connective Tissues Connective tissue proper and Cartilage -our second tissue type- Text readings: chapter 5

Connective Tissue Lecture Outline 1.Function and Common Characteristics of all Connective Tissues 2.Connective Tissue Proper : its cells, fibers, and ground substance 3.Connective Tissue Proper : mechanisms of growth 4.Connective Tissue Proper : most common arrangements in the body 5.Cartilage : its cells, fibers, and ground substance 6.Cartilage: mechanisms of growth 7.Cartilage : most common arrangements in the body 8.Bone : its cells, fibers, and ground substance 9.Bone : most common arrangements in the body 10.Bone : mechanisms of growth 154

155 Creating a structural framework by surrounding, supporting and joining tissues Protecting delicate organs Storing energy reserves (fat) Transporting fluids and dissolved materials (blood, lymph) Defending the body from microorganisms Connective tissue functions:

156 Classification of Connective Tissues

157 Specialized cells Extracellular Matrix Contains fibers which provide support Contains material called ground substance which fills in all space between cells and fibers. Components common to all Connective Tissues The binding properties of the ground substance determine the consistency of the connective tissue

158 Found everywhere in the body: between organs, around muscles, under skin Contains different cell types Contains 3 basic fiber types, but in differing proportions Contains a ground substance which is syrupy in consistency Connective tissue proper (general connective tissue)

159 Connective tissue proper: Cells Many different cell types : –Fibroblasts – the primary cell type; produce fibers and most components of ground substance –Macrophages – clean-up cells (phagocytosis) –Adipocytes – fat cells –Mesenchymal cells–connective tissue stem cells –Melanocytes–produce and store melanin pigment –Mast cells – histamine-containing cells –Lymphocytes – disease-fighting white blood cells

160 Three types of extracellular fibers, found in different proportions in different organs Connective tissue proper: Fibers

161 Growth of new Connective Tissue Proper: –Cells are free to move around, build more extracellular matrix when stimulated –Fibroblasts are responsible for scar formation following injury; they divide and increase their synthesis of extracelluar materials. Connective tissue proper : formation of the fibers In CT proper, fibroblasts produce the proteins which assemble to form fibers. fibroblast

Classified as loose or dense depending on how tightly packed the fibers are Loose –Embryonic mesenchyme, mucous connective tissues –Areolar tissue –Adipose tissue Dense –Dense regular CT –Dense irregular CT Connective tissue proper Loose packing allows space for migrating cells, blood vessels, nerves Dense packing of collagen fibers makes for a stronger tissue 162

163 Connective Tissue Proper Loose Areolar

164 Connective Tissue Proper Adipose Tissue (fat) Adipose Tissue Loose arrangement of fibers around fat cells (adipocytes) Fat Cells = Adipocytes

165 Dense Irregular Connective Tissue Densely packed with collagen fibers Collagen fibers are NOT regularly arranged : fibers run in all directions Provides good strength in all directions : connects most other parts of body

166 Dense Regular Connective Tissue Densely packed with collagen fibers Collagen fibers are regularly arranged: fibers run in parallel Tremendous strength in one direction: found in tendons and ligaments

Tendons and Ligaments are both built from dense regular connective tissue 167

168 Elastic Connective Tissue Densely packed with ELASTIC fibers Elastic fibers are regularly arranged

Connective Tissue Proper is found throughout the body arranged in sheets called fascia 169

170 Small thin plates of solid material Matrix is a firm gel containing chondroitin sulfate Cells called chondrocytes (chondroblasts=immature form) are located in lacunae (small fluid-filled spaces within cartilage plate) Perichondrium (CT proper) separates cartilage from surrounding tissues and contains chondroblasts which produce new cartilage Three types of cartilage: hyaline, elastic and fibrocartilage Different arrangements and proportions of collagen and elastic fibers Very different characteristics due to properties of matrix –Ranges from highly slippery to dense cushions Supporting connective tissues: Cartilage Text readings: chapter 5

171 Cartilage Cells produced fibers and ground substance, then became trapped in lacunae Note absence of blood vessels: cartilage is AVASCULAR and relies on diffusion of nutrients from blood vessels in perichondrium Cartilage heals poorly when injured =Fibers and ground substance

172 Growth of Cartilage: Interstitial Growth mature chondrocytes divide within their lacunae

173 Growth of Cartilage: Appositional Growth immature chondrocytes (chondroblasts) in perichondrium produce new cartilage along surface of mature cartilage

174 Types of Cartilage: Hyaline Cartilage The most common cartilage form in the body

175 Types of Cartilage: Elastic Cartilage

176 Very fibrous = mostly collagen fibers Little ground substance Types of Cartilage: Fibrocartilage