Section 2, Chapter 5 Connective Tissue
Connective Tissues Characteristics • Cells are interspersed • Contains an extracellular matrix • Contains protein fibers & a non-protein ground substance Cell nucleus
• Many have good blood supply • Most cells divide Extracellular matrix Elastic Cartilage
Cell Types - Fixed Cells (stationary) Fibroblasts • Secretes protein fibers into matrix
Fibroblast
Mast Cells • Secretes histamine & heparin into blood
Mast Cell
Cell Types – wandering cells Move throughout tissues Macrophages • Phagocytize bacteria & debris • Actively move about during infection
Macrophages
Connective Tissue Fibers produced by fibroblasts 1. Collagenous fibers •
Thick threads of collagen
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Flexible, but only slightly elastic
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Great tensile strength = resists pulling
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Forms ligaments & tendons Ligaments
Tendons
Connect bone to bone
Connect muscle to bone
Connective Tissue Fibers produced by fibroblasts 2. Elastic Fibers •
Elastin = Spring-like protein
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Weaker than collagen
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Easily stretched or deformed and retains shape
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Locations: vocal cords, respiratory tract, blood vessels
Figure 5.17 Scanning electron micrograph of collagenous fibers and elastic fibers
Connective Tissue Fibers produced by fibroblasts 3. Reticular Fibers •
Thin collagen fibers
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Forms reticulum = highly branched network
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Spleen, Liver, Lymph nodes
Reticular fiber
Types of connective tissue Connective Tissue Proper Loose Connective Tissue Areolar Adipose Reticular
Dense Connective Tissue Dense Regular C.T. Dense Irregular C.T. Elastic C.T.
Specialized Connective Tissue Cartilage Bone Blood
Loose Connective Tissue Areolar Tissue • Forms Delicate Membranes • Structure • Cells = Fibroblasts • Fibers = Collagenous & Elastic • Locations • Binds skin to organs • Between Muscles
Loose Connective Tissue Adipose Tissue (fat) • Stores fat & cushions organs • Structure • Cells = adipocytes • Fat droplets in cytoplasm • Locations • Beneath skin • Surrounds kidneys & eyeballs • Surface of heart
Loose Connective Tissue Reticular Connective Tissue • Forms reticulum = three-dimensional network • Structure • Cells = fibroblasts • Fibers = thin collagenous fibers • Framework of • Spleen • Liver • Lymph nodes
Dense Regular Connective Tissue • Structure • Cells = few fibroblasts • Fibers = tightly packed collagenous fibers • Very strong, withstands pulling forces • Tendons & Ligaments • Poor blood supply = slow to heal
Dense Irregular Connective Tissue • Structure • Cells = fibroblasts • Fibers = interwoven collagenous fibers • Withstands forces in all directions • Dermis of skin
Dermis (deep layer) of skin
Elastic Connective Tissue • Structure • Cells = fibroblasts • Fibers = mostly elastic, with few collagen • Provides elastic quality • Walls of larger arteries, and respiratory tract
Cartilage Overview Functions • Provides attachments • Protects tissue • Structural model for developing bone
Structure • Cells = chondrocytes • Extracellular matrix • Abundant collagen fibers • Gel-like ground substance • Lacunae = cavities containing chondrocytes
Hyaline Cartilage Fine collagenous fibers White glass appearance
Locations: End of bones & nose and costal cartilage of ribs Constitutes most of the embryonic skeleton
Elastic Cartilage Locations: Framework of Ear and larynx Contains a dense network of elastic fibers Flexible
Fibrocartilage Tough cartilage composed of dense collagen fibers Locations: Intervertebral Discs & Knee Functions: absorbs compression (acts as a shock absorber)
Bone •Characteristics •Most rigid connective tissue •Functions •Supports & Protects •Forms blood cells •Muscle Attachment •Structure •Mineral salts = hardness •Collagen fibers = flexibility •Cells = Osteocytes •Lacunae = Cavities containing osteoctyes
Blood • Fluid Matrix = Plasma • Cells • Red Blood Cells = transport gasses • White Blood Cells = fight infection • Platelets (cell fragments) = blood clotting
Overview of Connective Tissues
End Section 2, Chapter 5