Tissues Tissue Histology The Four Primary Tissue Types Epithelial Connective Muscular Nervous
Epithelial Tissue Epithelium / -a = cell layer (barrier) Covering or lining—inside and out Permeability control Sensation Glands = secretory structure
Structural Characteristics of Epithelia apical Cellularity Polarity Avascular Innervated Regenerative ability basal BM
Polarity of Epithelial Cells
Classification of Epithelia The function of the epithelium determines which type. Typically classified according to 1. Number of cell layers Simple vs. Stratified 2. Shape of cell Squamous, cuboidal, columnar Special features Cilia, villi, goblet cells End with epithelium to complete the naming
Arrangements Simple Stratified Pseudostratified Transitional
Shapes Squamous Cuboidal Columnar
Special Features Cilia Goblet Cells Microvilli Villi
Simple Squamous Epithelium 1 cell thick Friction reduction Diffusion/filtration Locations: Lining of ventral body cavities, e.g. peritoneum Lining of blood vessels (endothelium) Alveoli
Lung
Simple Cuboidal Epithelium Function: Secretion Absorption Location: Lining of ducts Glands (salivary, pancreas, thyroid) Kidney tubules
Thyroid Follicle
Simple Columnar Epithelium Functions Secretion Absorption Locations GI tract Excretory ducts Reproductive tract Special Features
Pseudostratified Ciliated Columnar Epithelium Function: Mucociliary Blanket Mixture of cell heights nuclei located at various distances from surface. Locations Respiratory tract except for lungs Male reproductive ducts
Stratified Squamous Epithelium Multiple layers = better protection Keratinized vs. non-keratinized Location? Where we need protection! Skin surface Entrances/exits of body
Stratified cuboidal and columnar: rare, found in glands and ducts Sweat gland
Transitional Epithelium Function Extreme expansion & recoil Layered appearance due to overcrowding. Location Bladder, ureters
stretched
Location in the Body
Connective Tissue: Supports, protects, binds tissues Structural characteristics: Specialized cells Extracellular matrix Protein fibers Ground substance Mostly highly vascular
Functions Structural framework Transport Support and protection Energy storage
Classification of Connective Tissue
Connective Tissue Proper Types: Areolar Dense regular Reticular Adipose Dense irregular Types of Fibers: Collagen Elastic Reticular Defense: Macrophages Plasma Cells Mast Cells Other WBC
Membranes = Combination of Epithelia & C.T. Mucous membranes Lining of cavities that communicate with exterior Serous membranes Lining of sealed, internal cavities Cutaneous membranes Skin Need to know membranes Parietal vs. visceral