Types of Epithelial Tissue Membranous: covering or lining of body and parts; Lines cavities, vessels, respiratory, digestive and urinary/ reproductive systems Glandular: grouped in spinal cord, specialized follicles in the endocrine and exocrine glands

Functions Protection: protection of body from chemical and mechanical injury; from bacteria and other microorganisms Sensory: skin, nose, eyes, ears Secretion: hormones, digestive juices, mucus, sweat Absorption: nutrients from the gut, respiratory gases in the lungs Excretion: kidney tubules for excretion of urine

Epithelial Info Attaches to connective tissue with the BASEMENT LAYER Contains no blood vessels; AVASCULAR Oxygen and nutrients come from capillaries in the basement layer

Membranous Epithelium Classified based on cell shape 4 types: Squamous: flat and platelike Cuboidal: cube shaped Columnar: higher than they are wide Pseudostratified Columnar: one layer of oddly shaped columnar cells, some cells do not reach the surface but all touch the basement layer

Membranous Epithelium Can also be classified based on layers of cells Simple Epithelium: single layer Stratified Epithelium: cells are layered on one another Transitional Epithelium: different cell shapes layered in a sheet

Simple Squamous Epithelium One layer of flat, scale-like cells Easy for substances to diffuse or filter across Found commonly in Aveoli in lungs, lining of blood vessels and lymphatic vessels Endothelium: blood and lymphatic vessel lining Mesothelium: surfaces of the pleura, pericardiaum, periteneum

Simple Cuboidal Epithelium One layer of cuboidal cells Found in glands and ducts and tubules of some organs (kidney)

Simple Columnar Epithelium Single layer of tall cells Surface of mucous membranes that line: stomach, intestines, uterus, uterine tubes, parts of respiratory system, goblet cells Contains MICROVILLI: increases surface area of intestinal mucosa

Pseudostratified Columnar Found in air passages and in certain segments of the male reproductive systems Why is it PSEUDOSTRATIFIED?

Stratified Squamous Keratinized Epithelium Multiple layers of typical flattened squamous cells at the outer surface of the epithelial sheet Presence of keratin helps with the protective qualities of the epithelium

Stratified Squamous Non-Keratinized Epithelium Found lining the vagina, mouth and esophagus Free surface is moist, does not contain keratin Serves a protective function

Stratified Cubiodal Two or more rows of cubiodal cells are arranged over the basement layer Located in the sweat gland ducts, pharynx, over the epiglottis (covers the larynx)

Stratified Columnar Only most superficial cells are truly columnar Located in the male urethra and mucousal layer near the anus

Stratified Transitional Found in areas that are subjected to stress and tension changes Wall of the urinary bladder

Glandular Epithelium Specialized for secretion Can function singly as unicellular glands or function in clusters, cords or follicles as multicellular glands All glands are either ENDOCRINE or EXOCRINE Exocrine: discharge secretion into ducts; ex. Salivary glands Endocrine: ductless, discharge hormones into blood or tissue; ex. Pituitary, thyroid and adrenal glands

Multicellular Exocrine Glands See table 5-5 for diagrams and descriptions APOCRINE GLANDS: collect their products near the tip of the cell and release into a duct by pinching off the end; Ex. Mammary Glands HOLOCRINE GLANDS: collect secretions inside the cell and then rupture to release; Ex. Sebaceous glands MEROCRINE GLANDS: discharge secretions directly through the cell membrane; Ex. Salivary glands