2. Has a free surface (Apical Surface)3. Bound to underlying tissue by a basement membrane4. Avasculara. Simple Epithelium – one layer thickb. Stratified Epi. – multiple layersa. Simple squamousb. Simple columnarc. Transitionald. Simple cuboidale. Nonkeratinized stratified squamousTISSUES II. CLASSIFICATION OF TISSUESA. Histology: microscopic study of tissuesB. 4 kinds: Epithelia, Connective, Muscle & NervousII. EPITHELIAA. Characteristics of Epithelia: covers body/organ surfaces, lines body cavities and forms glands1. very cellular2. Has a free surface (Apical Surface)3. Bound to underlying tissue by a basement membrane4. AvascularB. Classification1. Classified by LAYERS:a. Simple Epithelium – one layer thickb. Stratified Epi. – multiple layers2. Classified by cell SHAPE:a. Squamous – flattened cellsb. Cuboidal – cube-shaped cellsc. Columnar – rectangular-shaped cellsIII. TYPES OF SIMPLE EPITHELIAA. Simple Squamous Epithelium1. One layer of flattened cells2. Location: lines lumen (cavity) of blood vessels, tiny air sacs of lungs, covers body cavities3. Function: rapid diffusion and filtrationB. Simple Cuboidal Epithelium1. One layer of cube-shaped cells2. Location: lines ducts & tubules (e.g., salivary glands & kidneys)3. Function: secretion and absorptionC. Simple Columnar Epithelium (form “Goblet Cells” that make mucus)1. One layer of tall, rectangular-shaped cells. May have microvilli, goblet cells, or cilia.2. Location: lines most of GI (gastrointestinal tract)3. Function: secretion and absorptionD. Pseudostratified Columnar Epithelium1. One layer of columnar or irregularly shaped (tall and short) cells. Some kinds have cilia (pseudostratified CILIATED columnar epithelium) and goblet cells2. Location: lines trachea & bronchi3. Function: protection and secretionIV. TYPES OF STRATIFIED EPITHELIAA. Stratified Squamous Epithelium: Upper layers of cells are flattened, lower layers appear cuboidal. Deepest layers highly mitotic. Two kinds:1. Keratinized: contains keratin, superficial layers consist of dead cellsa. Location: epidermisb. Function: protection (barrier)2. Nonkeratinized: superficial cells are alive and kept moista. Location: oral cavity, pharynx, vagina, and the lower part of the anal canalb. Function: protectionB. Transitional Epithelium: some cells are binucleated. Surface cells may be dome-shaped or flattened.a. Location: found in most of urinary tract b. Function: withstands distention (stretching) and relaxingV. GLANDULAR EPITHELIA: Specialized epithelial tissues that have excretory functionsA. Exocrine Glands formed from epithelial tissues - they secrete their materials onto a free surface1. Unicellular: Goblet cells.a. Location: Respiratory & digestive systemsb. Function: secrete mucus2. Multicellular: secrete materials through a duct to a free surfacea. merocrine glands: secretes watery fluid through the cell membrane. Example: salivary glandsb. apocrine glands: top part of the cell is pinched off, it becomes the secretion. Example - mammary glandsc. holocrine glands: Entire cell is released & it ruptures & dies. Example: sebaceous (oil) gland.Which of the following epithelial tissues allows for rapid filtration and diffusion?a. Simple squamousb. Simple columnarc. Transitionald. Simple cuboidale. Nonkeratinized stratified