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What are the 4 basic tissue types?
Epithelial tissue, Connective tissue, Muscle tissue, Nervous tissue
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Epithelial Tissue
covers or lines the external and internal surfaces of the body
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Connective tissue
fills space between other tissues
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Muscle Tissue
contractile properties. Gives mobility and tegulates blood flow.
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Nervous Tissue
permits interaction with the environment and integration of tissue function
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What are the functions of Connective Tissue?
- To provide support strength, elasticity, and incompressibility
- To provide environment for infiltration of immune cells
- Importan in defense, inflammatory responses and tissue repair
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Cells of connective tissue:
- Fibroblast: resident cells
- Adipocytes: (fat cells) and cells that migrate in from blood
- Macrophages: immune cells derived from blood-borne monocytes
- Plasma cells: immune cells that develop from B lymphocytes
- Mast cells: produce histamine- part of defense system- overactive in allergy
- Other blood cells like eosinophils and neutrophils migrate into connective tissue in injury and infection
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Major Classes of Macromolecules of ECM (extracellular matrix)
- Proteoglycans/ Glycosaminoglycans
- Fibrillar proteins (eg. collagen, elastin, and reticular fibers)
- Glycoprotein (eg. fibronectin and laminin)
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Major Glycosaminoglycans (GAGs)
- Hyaluronic acid (hyaluronate): unsulfated- synovial fluid, vitreous humor
- Chondroitin sulfates: may be sulfated- cartilage, bone, heart valves - the most abundant GAG
- Heparin and Heparin sulfate: basement membranes
- Keratan sulfate: cornea, cartilage
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Functions of GAGs
- Gel-like properties allow GAGs to resist compressive forces
- Allow rapid diffusion of water soluble molecules through ECM
- Specifically sequester certain growth factors in the matrix
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Proteoglycans
-A proteoglycan monomer consists of a core protein with GAG side chains
-The major proteoglycan in cartilage froms large aggregates with hyaluronic acid as a backbone
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Collagens
-Characterized by triple helical structure of 3 polypeptide chains
-Sequence of chains [Gly-X-Y]n
-X is the proline and Y is usually hydroxproline
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