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Epithelial Tissue. Page 78 - 81. Characteristics. Fit closely together to form continuous sheets. Has an apical surface which is a free surface that is exposed to the body’s exterior or to the cavity of an internal organ. Has a basement membrane which is where the lower surface is attached.
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Epithelial Tissue Page 78 - 81
Characteristics • Fit closely together to form continuous sheets. • Has an apical surface which is a free surface that is exposed to the body’s exterior or to the cavity of an internal organ. • Has a basement membrane which is where the lower surface is attached. • No blood supply or avascular. • Can regenerate themselves easily.
Classification of Epithelium Arrangement Shape Squamous – flattened Cuboidal – cube-shaped like dice Columnar – shaped like columns • Simple – one layer of cells • Stratified – more than one cell layer
Types of Simple Epithelial Cells • Simple squamous • Simple cuboidal • Simple columnar • Pseudostratified columnar
Simple Squamous Epithelium • Single layer of thin squamous cells • Lines air sacs of lungs, walls of capillaries and forms the serous membranes
Simple Cuboidal Epithelium • Single layer of cuboidal cells • Found in salivary glands and pancreas
Simple Columnar Epithelium • Single layer of tall cells • Goblet cells (produce a lubricating mucus)are often present • Lines entire digestive tract from stomach to anus
Pseudostratified Columnar • Single layer of columnar cell with different heights giving it a multiple layer look. • Goble cell often present • Cells found in the respiratory tract have cilia (ciliated).
Types of Stratified Epithelia • Stratified squamous • Stratified cuboidal • transitional
Stratified Squamous Epithelium • Several layers of squamous cells with either cuboidal or columnar cells near the basement membrane. • Found in the esophagus, mouth, and outer portion of the skin.
Stratified Cuboidal & Stratified Columnar Epithelia • Rare • Found mainly in the ducts of large glands
Transitional Epithelium • Highly modified, stratified squamous epithelium found in the bladder, ureters, and part of urethra. • Cells change shape to adapt to considerable stretching.
Glandular Epithelium • Endocrine glands • Has no connection to the surface – ductless glands • Ex. Thyroid, adrenal, pituitary • Exocrine glands • Secretions empty through the ducts to the epithelial surface • Ex. Sweat and oil glands (external surface), liver and pancreas (internal surface)