Question | Answer |
what is histology | a conglomeration of cells that perform a particular function |
what germ layer is epithelial derived from | all 3 germ layers, ectoderm,mesoderm,endoderm |
What is the function of epithelial tissue | covers and lines, and forms glands |
Characteristics of epethelial tissue | cells are held closely with little or no intercellular (between cells) matrix. |
what are the 3 types of junctions | tight junction: holds cells tightly together to prevent leakage.Anchoring junction: allows distention of tissue.Gap or communicating junction: allows spread of electrical and chemical messages from cell to cell. |
Desosomes | protein welds that hold the cells of the epithelial together. |
How are cells arranged | in sheets |
epithelial has high mitotic ability | quickly regenerates because of wear and tear. |
epithelial has 2 surfaces | apical: top or outer surface(unattached)basal surface:bottom surface(attached to basement membrane.) |
what two layers does the basement membrane have? | basal lamina which is the top layer, and consists of collagen(protein) and proteoglycans.reticula lamina is the bottom layer which consists of glycoproteins and reticular fibers. |
What is the function of the basement membrane: | acts as an attachment of epithelial cells at basal surface,Nutrient and waste exchange between the two tissues.serves as a guideline for migrating cells during mitotic division. |
epithelial is avasuclar(no blood supply) | depends highly on vascularized connective tissue below it to support it and supply nutrients. ( nutrients and waste exchange occurs at the basement membrane that connects the two tissues. |
what is classification based on | layering affect and cell shape. |
what are the 3 layering effects | simple- 1 layer thick...allows diffusion, osmosis, secretion, excretion.stratified- 2 or more layers..allows protection and named by cell shape in top layers .pseudostratified-false stratification...appears stratified but is really simple. |
Pseudostratified-false stratification | appears stratified but is simple. all cells in this tissue come in contact with the basement membrane but do not reach the surface at the same levels. |
4 cell shapes | squamous, cuboidal, columnar, transitional |
squamous | flat, tile like cells with a disc shaped nucleus |
cuboidal | cube shaped with a sperical nucleus |
columnar | column shaped with an elongated nucleus (close to base) |
columnar have 3 modifications associated with them | cilia for movement, microvilli enhances surface area for better absorption and goblet cells unicellular epithelial glands and secret mucus for protection |
transitional | rounded cells, 2 nuclei, allows distention(stretch) |
What shapes are in simple layering | squamous, cuboidal and columnar |
what shapes are in stratified layering | squamous, cuboidal, columnar, and transitional |
what shapes are in pseudostratified | columnar |
simple squamous epithelium | consists of one layer of flat cells with a disc shaped nucleus. located in alveoli(airsacs), glomerulus of nephrons in kidney, tympanic membrane of eardrum, mesothelium, lining of the heart, blood vessels esp. capillaries, and lymph vessels esp. lacteals |
simple cuboidal epithelium | consists of one layer of cube shaped cells. location: foms ducts and tubules, capsule of eye lens, surface of ovary, pigmented epithelium of eye, thyroid gland. |
simple columnar epithelium | consists of one layer of column shaped cells with an elongated nucleus |