Epithelial Tissues

First name indicates number of layers  Simple = 1 layer of cells  Stratified = > 1 layer Classifications & Naming of Epithelia

Last name describes shape of cells  Squamous – (plate, flat, scale-like)  Cuboidal – (cubeish)  Columnar – (column, tube) EX: simple cuboidal = ??

Special epithelial tissues  Pseudostratified (look multi-layered, but aren’t)  Transitional Add accessory structures  Goblet  Cilia (ciliated simple columnar…)  Keratin (keratinized stratified squamous…

Simple Squamous Special types  Endotheliums covering inner hollow side of organs slick  Mesotheliums lining middle cavities peritoneal, pleural, and pericardial covers visceral organs of those cavities

Simple Squamous Special features  Flat, disc-shaped nucleus Function  Transport, filter, secrete lubricant Location  Kidney, lungs, blood, lymph  Lining of heart

Simple Squamous Simple squamous; capillaries

Simple Cuboidal Special features  large, spherical central nuclei Function  secrete and absorb Location  kidney tubules, small glands, ovary & thyroid follicles

Simple Columnar Special features  oval nuclei may have cilia at apical surface May be goblet cells Function  Absorb, secrete mucus, enzymes, etc

Simple Columnar Location  Non-ciliated digestive tract, gallbladder, ducts of some glands  Ciliated bronchi, fallopian tubes

Pseudostratified Columnar Description  All cells originate at basement membrane  Only tall cells reach apical surface  May contain goblet cells & cilia  Nuclei at varying heights Function  secrete mucus;,move mucus by cilia

Pseudostratified Columnar Locations  Non-ciliated Ducts of male reproductive tubes Ducts of large glands  Ciliated Lines trachea & most upper respiratory tract

Stratified Epithelia two or more layers Regenerate from below Major role is protection named by shape of cells at apical layer

Stratified Squamous Description  Many layers – squamous  Deeper layers appear cuboidal or columnar  Thickest  Protection

Stratified Squamous Specific types  Keratinized –protective protein keratin Surface cells dead & full of keratin  Non-keratinized – form moist lining of body openings Function  Protect tissues in areas subject to abrasion Location  Keratinized –epidermis (skin)  Non-keratinized – esophagus, mouth, and vagina

Transitional Epithelium Description  Basal cells usually cuboidal or columnar  Superficial cells dome- shaped or squamous Function  stretches Location  ureters, urinary bladder & part of urethra

Glandular Epithelium Ducts carry products of exocrine glands to epithelial surface Include diverse glands  Mucus-secreting  Sweat and oil  Salivary  Liver & pancreas  Mammary May be: unicellular or multicellular

Unicellular Exocrine Glands (Goblet Cell) produce mucin Mucin + water  mucus Protect & lubricate internal body surfaces

Multicellular Exocrine Glands by structure: branching & shape by method:  Merocrine – vesicles released via exocytosis (salivary gland)  Apocrine – apical portion of cell + cytoplasm + secretory product (mammary gland)  Holocrine – entire cell lost (sebaceous gland)

By type  Serous: mostly water + some enzymes parotid glands, pancreas  Mucus: mucin + water sublingual glands, goblet cells  Mixed: serous + mucus submandibular gland