WEEK 3: Epithelial Tissues (Lecture) Flashcards
(23 cards)
composed of closely aggregated polyhedral cells adhering strongly to one another and to a thin layer (small amount) of ECM, forming cellular sheets that line the cavities of organs and cover the body surface.
Epithelial Tissues
The principal functions of the epithelial tissues include the following: CAS
Covering, lining and protecting surfaces
Absorption
Secretion
All epithelial cells don’t have veins or also called ______
avascular
All epithelial cells undergo _____. Under certain abnormal conditions, one type of epithelial tissue may undergo transformation into another type in another reversible process called _____.
metaplasia
Epithelial Cell Junction.
Function: Seals adjacent cells to one another, controlling passage of molecules between them; separates apical and basolateral membrane domains.
Junctional protein: Occludins, claudins and ZO proteins
Tight Junction (Zonula Occludens)
Epithelial Cell Junction.
Function: Provides points linking the cytoskeletons of adjacent cells; strengthens and stabilizes nearby tight junctions.
Junctional Proteins: E-cadherin, catenin complexes
Adherens Junction (Zonula Adherens)
Epithelial Cell Junction.
Function: Provides points of strong intermediate filament coupling between adjacent cells, strengthening the tissue
Junctional Protein: Desmogleins and Desmocollin
Desmosomes
Epithelial Cell Junction.
Function: Anchors cytoskeleton to the basal lamina
Junctional Proteins: Integrins
Hemidesmosomes
Epithelial Cell Junction.
Function: Allow direct transfer of small molecules and ions from one cell to another.
Junctional Protein: Connexins (1 connexons: 6 connexins)
Gap Junctions or Communicating Junction (Nexus)
Morphology. Thin and flat cells
Squamous
Morphology. Cell width and thickness roughly similar. Square
Cuboidal
Morphology. Cells taller than they are wide. Rectangular
Columnar
One cell layer
Simple epithelia
Two or more cell layers
Stratified epithelia
Surface Modifications. Are long, highly motile apical structures, larger than microvilli, and containing internal arrays of microtubules not microfilaments.
Cilia
Surface Modifications. Specialized for absorption usually of uniform length. In cells such as those lining the small intestine, densely packed _____ are visible as a brush or striated border projecting into the lumen.
Microvilli
Surface Modifications. Are a much less common type of apical process best seen on the absorptive epithelial cells lining the male reproductive system. Increase the cells’ surface area, facilitating absorption. Important components of inner ear sensory cells.
Stereocilia
A layer of flat cells derived from the mesoderm. It lines the coelom (the body cavity of the embryo) and forms the simple squamous epithelium covering true serous membranes such as the peritoneum, pericardium, and pleura
Mesothelium
Another type of simple squamous epithelium that lines the inner surface of blood vessels, including arteries, veins and capillaries
Endothelium
These cells are found in glandular tissue. They have contractile properties and surround secretory cells in glands, assisting in the release of glandular products.
Myoepithelium
Lines the inner surface of the uterus. It undergoes cyclic changes during the menstrual cycle and plays a vital role in implantation and pregnancy.
Endometrium
A misnomer. Historically believed to be the source of germ cells or gametes (eggs and sperm) in the gonads. However, the actual site of germ cell production is the ovarian follicles and seminiferous tubules.
Germinal Epithelium
Also known as glandular tissue, produces and release various secretory products. These include sweat, saliva, breast milk, digestive enzymes, and hormones, among others.
Glandular Epithelium
