Tissue Tissues Chapter 3 Definition an aggregation of cells in which each cooperates with all others in the performance of a given function Examples of general functions Movement Protection Support Production of chemicals Epithelial Connective Muscular Nervous Principal Tissue Types Functions Coverings and linings Forms glands Characteristics Closely packed cells Continuous sheets Basement membrane Avascular Classification Simple Stratified Epithelial Tissue Squamous Epithelium Epithelia of Coverings and Linings Simple Squamous Epithelium Highly adapted to diffusion, osmosis, & filtration 1
Squamous Epithelium Cuboidal Epithelium Simple cuboidal Stratified Squamous Epithelium Function secretion and absorption Lines glands and their ducts Surface layer is flat Function protection Stratified Cuboidal Surface layer cubeshaped Function protection Glandular Epithelium Gland 1 or more cells Function secretion Types Exocrine to surface or ducts Endocrine to blood Transitional Epithelium Can be stretched Lines hollow structures that expand Function prevents rupture of organ http://www.mhhe.com/biosci/ap/histology_mh/stratepi.html Columnar Epithelia Simple columnar Appear stratified but all cells connect to the basement membrane Functions Functions Protection, Absorption or secretion Stratified columnar More than one layer Function Protection Pseudostratified Columnar Epithelium Protection Secretion http://bioweb.uwlax.edu/zoolab/table_of_contents/lab1b/pseudostratified_model_1/pseudostratified_model_1.htm 2
Connective Tissue Most abundant tissue Functions are varied Characteristics Specialized cells, widely scattered Rich blood supply Much matrix Extracellular fibers Ground substance Cell Types Found in Connective Tissue Fibroblasts Secrete the molecules that form the matrix Fixed cells Fibrocytes Macrophages Big eaters May be fixed or wandering Connective Tissue Fibers Collagen fibers Most common type White Strong, ropelike Form ligaments, tendons Reticular fibers Thin Woven into rough, flexible network Elastic fibers Yellow Thin Stretch Contain elastin Ground Substance Extracellular fluid in connective tissue Water Glycoproteins Types of Connective Tissue Loose (Areolar) Connective Tissue Fibers not abundant Contains all 3 types of fibers Examples of locations Between skin and muscles Around digestive tract Around blood vessels 3
Adipose Tissue Most of the volume is adipocytes Provides padding, slows heat loss, food reserve Locations Wherever there is loose connective tissue Types Dense Connective Tissue Dense Regular Connective Tissue Dense Irregular Connective Tissue Elastic Connective Tissue Dense Regular Connective Tissue Lots of collagen fibers in bundles Cells fibroblasts in rows between bundles Examples Tendons, ligaments Dense Irregular Connective Tissue Tensions in various directions Occurs in sheets Locations Periosteum Perichondrium Fibrous capsules of some organs Fasciae Dermis Elastic Tissue Lots of elastic fibers Fibroblasts in spaces between fibers Provides stretch and strength Cartilage Dense network of collagenous fibers & elastic fibers in a gel-like substance Cells chondrocytes in lacunae Chondroblasts Perichondrium surrounds surface of cartilage 4
Types of Cartilage Hyaline Cartilage Most common Provides flexibility and support Locations Hyaline cartilage Fibrocartilage Elastic cartilage Ends of bones Trachea Larynx Embryonic skeleton Fibrocartilage Visible collagenous fibers with scattered chondrocytes Provides strength and rigidity Locations Intervertebral discs Symphysis pubis Elastic Cartilage Threadlike network of elastic fibers with chondrocytes Provides strength and maintains shape Locations Pinna Eustacian tube Bone Blood Functions Solid matrix Cells Transport medium Regulation Protection Osteocytes in lacunae Osteoblasts Osteoclasts Composition Plasma fluid Formed elements cells & cell fragments Periosteum surrounds surface of bone Erythrocyte Leukocyte Thrombocyte 5
A Red Blood Cell SEM of RBCs Muscular Tissue Specialized cells Function - contraction 3 types Skeletal Muscle Connected to bones Striated Multinucleated Voluntary Skeletal muscle Cardiac muscle Smooth muscle Cardiac Muscle Found in the heart Striations Intercalated discs Involuntary Smooth Muscle Found in walls of internal organs Nonstriated Involuntary 6
Nervous Tissue Specialized cells Function conduction of electrical impulses Cells Neurons Neuroglia 7