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Squamous Meaning square-like. Cuboidal Meaning cube-like. Columnar Meaning column-like. Pseudo Meaning false or fake. Stratified Meaning more than one. Simple Meaning just one. Characteristics of Simple Squamous Epithelia Thin, permeable. Located where rapid diffusion is required. Lines heart, vessels, glomeruli, alveoli. Endothelium Inside of hollow tubes to reduce friction. (Inside Epithelium) Mesothelium Lining the ventral body cavity and its organs. What comprises the Basement Membrane? Basal Lamina + Reticular Lamina What is the Basal Lamina? Thin supporting sheet, noncellular, consisting largely of glycoproteins and fine collagen fibers. Also lets underlying connective tissue enter the epithelium to repair tissue. What is the Reticular Lamina? A layer of extracellular material containing a fine network of collagen protein fibers that belongs to underlying connective tissue. Apical Top part (also known as free) Basal Bottom part Simple Epithelium Functions Absorption, Filtration, and Secretion Most important part for classification Bottom (Basal) area. Membrane Means opens from body to outside Microvilli Fingerlike extensions of the plasma membrane Cilia Tiny hairlike projections that propel substances along their free surface. Nucleous Shape of Squamous Flattened Disc Nucleous Shape of Cuboidadl Spherical Nucleous Shape of Columnar Elongated from top to bottom, located close to cell base. Function of Simple Cuboidal Epithelium Secretion and absorption Function of Simple Squamous Epithelium Allows passage of materials by diffusion and filtration in sites where protection is not important. Secretes muscous in serosae. Function of Simple Columnar Epithelium Absorption; secretion of mucus, enzymes, and other substances. Mostly lines digestive tract and some sections of the uterus. Function of Pseudostratified Columnar Epithelium Secretion, particularly of mucus; propulsion of mucus by ciliary action. Lines the trachea, most of the upper respiratory tract. What is the most the most common Stratified Epithelia? Stratified Squamous Epithelium Location of Stratified Squamous Epithelium It forms the external part of the skin and extends a short distance into every body opening that is directly continuous with the skin. Mainly in skin, mouth, esophagus, and vagina. Function of Transitional Epithelium Stretches readily and permits distension of urinary organ by contained urine. Location of Pseudostratified Columnar They are rare, and exist in the male urethrea. Major Role of Stratified Epithelia Protection Glandular Epithelia One or more cells that make and secrete products. Aqueous, mostly protein but can be lipid or steroid rich. Exocrine Glands "Ductless Glands" that produce hormones. Hormones Regulatory chemicals that are secreted by exocytosis directly into extracellular space, entering the blood directly and targetting organs. Exocrine Glands They secrete their products onto body surfaces (skin) or into body cavities. Mucin A complex glycoprotein that dissolves in water when secreted that forms mucus, a slimy coating that protects and lubricates surfaces. Goblet Cells Are cuplike accumulation of mucin that destends the top of the cell, making the cells look like glass with a stem. Simple Duct Structure Does not branch Compound Duct Structure Duct branches Tubular Secretory Structure Tube like classification Alveolar Secretory Structure Bulbous Shape Tubuloalveolar If they have both types of secretory units. Merocrine Glands Secrete their products by exocytosis as they are produced. The pancreas, most sweat glands, and salivary glands belong to this class. Holocrine Glands Accumulate their products within them until they rupture. Sebaceous (oil) glands of the skin are the only true example of holocrine glands.