Cuboidal Cells At The Basement Layer example essay topic

HISTOLOGY: TISSUES AND MEMBRANES Four Basic Types of Tissue = epithelial tissue, muscular tissue, nervous tissue, and connective tissue o See previous handout which discusses various types of connective tissues TISSUE TYPES AND CHARACTERISTICS (refer to chapter 6 in the lab manual and chapter 3 in the text) EPITHELIAL TISSUE = highly cellular tissue that forms coverings and linings of the body. Epithelial tissue attaches to underlying layers by way of a basement membrane that is a non-cellular adhesive layer. For instance, in the skin, the epidermis is made of epithelial tissue that is attached to the underlying dermis by a basement membrane. The basement membrane consists of glycoproteins and both fine and coarse protein filament which are produced by connective tissue cells. Epithelial tissue is classified according to the shape of the cells and the number of cell layers present.

Epithelial cell shapes = squamous (flattened), cuboidal, or columnar Simple epithelium is only one cell layer thick. Stratified epithelium is more than one cell layer thick. Simple Squamous Epithelium Location in the body: air sacs of the lungs, lining of blood vessels, many body membranes, part of the kidney tubules Structure: one layer of flat cells that lie on the basement membrane Function: provides a smooth, slippery surface to reduce friction and allows for diffusion of substances during absorption or secretion Simple Cuboidal Epithelium Location in the body: forms many of the major glands and ducts, lines tubules (such as sweat ducts) and tubules of the kidney Structure: one layer of tube-like or pie-like shaped cells (sort of like squashed cubes) that are fairly uniform in diameter attached to the basement membrane Function: often involved in the secretion of fluids (sweat, oil) or in filtration (as in the kidney) Simple Columnar Epithelium Location in the body: ciliated type lines the Fallopian tubes; non-ciliated type lines the digestive tract Structure: one layer of tall column-like cells attached to the basement membrane; the cells may be ciliated or non-ciliated Function: assists in the movement of substances through tubes in the body and plays vital roles in the process of absorption in the intestines; protection, absorption, and secretion cilium ( = singular; cilia is plural) = a slender organelle that extends above the free surface of an epithelial cell, and usually undergoes coordinated cycles of movement Pseudo stratified Ciliated Columnar Epithelium Location in the body: lines portions of the respiratory tract and the male reproductive tract Structure: one layer of ciliated columnar cells attached to the basement membrane, although it may look like it is formed from multiple cell layers Function: produces a mucus and traps small particles which are carried out of the lungs via coordinated movements of the cilia Stratified Squamous Epithelium Location in the body: surface of the skin, lines the vagina, mouth, throat and anus Structure: multiple layers of flat cells attached to the basement membrane; may have cuboidal cells at the basement layer, but the cells along the free edge are flattened; these flattened cells may be keratinized or non- keratinized; keratin is a tough protein that hardens cells in the outer layers of the skin, hair and nails Function: multiple cell layers protect underlying layers from abrasive, pathogenic, or chemical damage Stratified Cuboidal Epithelium (multiple layers of cuboidal cells) is relatively rare, but provides for some protection, secretion and absorption in some ducts (e.g. sweat gland ducts). Stratified Columnar Epithelium (multiple layers of columnar cells) is relatively rare, but provides for some protection in salivary gland ducts, the epiglottis, mammary ducts and the urethra. Transitional Epithelium Location in the body: lines the renal pelvis, urinary bladder and ureters Structure: multiple layers of irregularly shaped cells lie on top of the bladder, but the cells along the free edge are not flattened (as in stratified squamous epithelium); when the bladder fills, the cells along the free edge flatten out Function: the cell structure and multiple layers have an unusual amount of stretching capacity that allow for significant changes in the volume of portions of the urinary tract..