Epithelium Michael Hall PhD University of California Los Angeles Features common to all epithelia 1.The cells are closely packed together 2.The cells are polarized 3.The apex always faces an open space 4.The base always sits on a basement membrane Epithelial cells are closely packed Epithelial cells always have a free surface and sit on a basement membrane Free Surface Lamina propria Epithelium Basement membrane Note that both of the epithelia face a free surface Basement membrane Epithelium Types of Epithelium Simple One cell layer Stratified More than one cell layer Types of Epithelium 1. Simple squamous 2. Simple cuboidal 3. Simple columnar 4. Stratified squamous 5. Stratified cuboidal 6. Stratified columnar 7. Pseudostratified Simple squamous epithelium Free space Basement membrane Connective tissue Simple squamous epithelium (endothelium) lining an arteriole endothelium Simple cuboidal epithelium (kidney) Basement membranes Free surface Simple epithelia in kidney medulla scu ssq scu* ssq ssq scu scu Simple columnar epithelium (duodenum) Stratified Squamous Epithelium (cornea) free surface bm ct Stratified Squamous Epithelium free surface squamous cells basement membrane Stratified Cuboidal Epithelium Connective tissue Duct of sweat gland Basement membrane Stratified Columnar Epithelium (urethra) lp bm Columnar cells Pseudostratified Epithelium Pseudostratified Columnar Epithelium (duodenum) Basement Membrane Basal cells Transitional Epithelium (Urinary system) Transitional Epithelium (relaxed -top layer of cells is cuboidal) basement membrane Transitional Epithelium (stretched-top layer basement membrane of cells is squamous) Mesothelium Mesothelium is the name given to the simple squamous epithelium that lines the closed cavities of the body endothelium Endothelium Basement membranes Simple squamous epithelium Basement membrane Connective tissue Basement Membrane of epithelium Molecular structure of extracellular matrix forming the basement membrane Inside of cell Junctional Complexes ‘Terminal Bars’ between epithelial cells Epithelial Z. occludens Junctional Z. adherens Complex Cell 1 Cell 2 Desmosome Components of the 1 Epithelial Junctional Complex 2 1. Z. occludens 2. Z. adherens 3. Macula 3 adherens (desmosome) 4. Gap junction 5. Hemidesmosome 4 5 Cell 1 Cell 2 Generalized Structure of a Junctional Complex Connexon 1 Connexon 2 Gap Junction < 1,500 Da > 1,500 Da Surface Specializations of Epithelial Cells Villin Actin Structure of a microvillus Fimbrin Myosin Spectrin Stereocilia in the Epididymis Stereocilia Cilia in the Respiratory Mucosa Cilia cilia microvilli Components of a Mucosa Basement membrane Mucosa The End Whoopee !!
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