Good fences make good neighbors Epithelial Tissues Good fences make good neighbors

Epithelial Tissues Cover ALL body surfaces, line organs, are major tissues of glands 1 side is exposed to open space, underside is attached to connective tissue by a thin, non-cellular basement membrane Lack blood vessels, fed by diffusion from well vascularized connective tissues

More Epithelial Characteristics Reproduce rapidly Tightly packed Good barriers: Skin, lining of mouth Involved in secretion, absorption, excretion, sensory reception

Simple Squamous Epithelium 1 layer, thin, flattened Broad, thin nucleus Things pass through these easily: diffusion, filtration Easily damaged Found in: Alveoli, capillary walls, blood, lymph vessel lining, body cavity lining

Simple Squamous Epithelium

Simple Squamous Epithelium

Simple Cuboidal Epithelium 1 layer, cube shaped cells Central, spherical nucleus Covers ovaries, kidney tubules, glandular ducts (salivary, thyroid, pancreas, liver) Secretion (in glands) Absorption (kidneys)

Simple Cuboidal Epithelium

Simple Cuboidal Epithelium                                                                                                     

Simple Columnar Epithelium Elongated, 1 layer Nuclei located near basement membrane on about the same level Line uterus, most organs of digestive tract Thick, protective of underlying structures Secretes digestive fluids, absorbs nutrients Can have microvilli Can have goblet cells embedded, secrete mucus onto surface

Simple Columnar Epithelium

Simple Columnar Epithelium

Pseudostratified Columnar Epithelium Appear layered, but not: Nuclei stacked at different levels Often found with cilia, goblet cells scattered throughout Lines respiratory, reproductive systems

Pseudostratified Columnar Epithelium

Stratified Squamous Epithelium Thick, composed of several layers Cell division at deeper layers, older cells get pushed up/out In epidermis, lines mouth, throat, vagina, anus In epidermis, keratin (a tough protein) causes old cells to harden and die, forming a protective layer. Keritinization causes cells to become tough, dry This keeps water in, chemicals, microbes out

Stratified Squamous Epithelium

Stratified Cuboidal Epithelium Have 2-3 layers which line a lumen Line larger ducts like in mammary glands, sweat glands, salivary glands, pancreas Also found lining ovarian follicles, seminiferous tubules

Stratified Cuboidal Epithelium

Stratified Columnar Epithelium Layers of cells Superficial (shallow) cells are elongated, deeper cells (basal layers) are cuboidal Found in male urethra, vas deferens, parts of pharynx

Stratified Columnar Epithelium

Stratified Columnar Epithelium vs Stratified Cuboidal Epithelium

Transitional Epithelium Changes in response to tension: stretchy Inner lining of bladder, lining of urinary passages Several layers of cuboidal cells Flatten when stretched, cuboidal when relaxed Keeps urine in

Transitional Epithelium

Transitional Epithelium

Glandular Epithelium Specialized to make and secrete a product Found mostly within cuboidal and columnar epithelia Exocrine glands secrete into ducts. Merocrine glands: watery, protein-rich secretions Serous Cells: secretions are watery, enzyme filled (serous fluid): found in glands in body cavities Mucous cells: secrete thick mucous containing mucin, a glycoprotein: In digestive, respiratory systems Holocrine Glands: cell bursts during secretion Apocrine glands: cell loses some cytoplasm during secretion Endocrine glands secrete into blood

Glandular Epithelium