NUR 0012Exam # 2 Study Guide Lectures: 8 - 15Lecture 8 (September 17):What are the major characteristics of epithelial tissue?They exhibit cellularity because of the small amount of extracellular matrix between the cells. Epithelial cells all share special cell contacts like desmosomes and tight junctions that bind the adjacent cells together. In addition, they exhibit polarity with distinct upper and lower regions. They contain both a free surface which is not associated with any other cells and a basement membrane which attaches the cells to the underlying tissue. They are also supported by connective tissue. The reticular lamina and the basal lamina form the basement membrane of the epithelia. Furthermore, epithelia are avascular but innervated. Blood vessels don’t penetrate basement membrane to reach epithelium, but they do contain a nerve supply. Gases and nutrients that are in the blood can only reach the cells by diffusing across the basement membrane. Epithelia also exhibit regeneration by replacing themselves often via mitosis. Lastly, epithelia can be found covering surfaces such as the digestive tract and outside of the body. They can also form glands and membranes. Discuss the structure, functions, and locations of the epithelial tissues we discussed in class.Epithelia are classified by how many layers they contain and the shape of their cells. With regard to the number of cell layers, they can be classified as simple, stratified, pseudostratified, or transitional. Simple epithelia have only one cell layer with each cell extending from the basement membrane to the apical surface. They are found in organs that generally serve the functions of diffusion, filtration, secretion, and absorption. They are adapted to areas in which substances need to cross membranes easily. Stratified epithelia contain more than one layer of cells with only one of the layers being adjacent to the basement membrane. They are found in places where protection is important because as their outer layers are damaged, new layers are produced to replace them. Pseudostratified epithelia cells are all attached to the basement membrane, but only some of the cells reach the free surface while the folding of others gives it a stratified appearance. Lastly, transitional epithelium is a special type of stratified epithelium that can only be found in the bladder and ureters.With regard to the shape of epithelia cells, they can be classified as squamous, cuboidal, or columnar. Squamous cells are flat and sheet-like. They allow substances to diffuse through themand can act as filters. Cuboidal cells are cube-like and about the same height and width. Columnar cells are tall and thin. Cuboidal and columnar cells generally secrete or absorb substances since they have a greater cytoplasmic volume than squamous.There are many different specific types of epithelia found in the body that serve to aid in specific functions. We will start with the simple (one layered cells). Simple squamous cells are flat with a central nucleus found in places with little wear and tear and where substances are diffused and filtered. They can specifically be found in the alveoli, glomeruli, lens of the eye, endothelium, and capillaries. Simple cuboidal cells are cube shaped and have a central nucleus. They can be found in tubules where they can reabsorb substances such as collecting ducts of kidneys and surfaces of the ovaries. Simple columnar cells are column shaped and have a nucleus near the bottom of the cell. They can be found lining the digestive tract where they secrete mucous from goblet cells and absorb substances. Pseudostratified cells all touch the basement membrane, but don’t reach the free surface. They can be found in the respiratory tract where they release mucous to coat the passageways from their specialized goblet cells. Lecture 9 (September 19): Next we will discuss the stratified cell types found in the body. Stratified squamous contain many layers with the outside layer being flat and scale-like and the underlying layers being morecuboidal or column shaped. They can be found in the epidermis, inside the oral cavity, esophagus, and the vaginal canal. Generally, wherever protection is needed and where the outer layers can be abraded. In the epidermis, the keratin also acts as a waterproofing agent that fights water loss. Stratified cuboidal cells are rare, but can be found in the sweat glands and ovarian follicles where protection and secretion are needed. Stratified columnar are also rare, but can be found in the male urethra where protection and secretion are needed. Lastly, transitional epithelia look like stacks of cuboidal cells in their relaxed state, but the layers closest to the free surface can distend as the bladder fills. They allow the urinary bladder to stretch as it fills. They can typically be found in the bladder, urethra, and ureters. What are the characteristics of all connective tissues?They all develop from an embryonic tissue called mesenchyme, have an abundant extracellular matrix separating the cells, and contain 3 types of cells common to all of them. The extracellularmatrix contains 3 main components (protein fibers, ground substances, and H2O). There are 3 different types of protein fibers found in the EM. Collagen is rope-like and strong but not flexible. Reticular fibers are tiny collagen fibers that act like a web between tissues. Elastin are elastic proteins that can be stretched but have the ability to return to their original shape. The ground substances include interstitial fluid, cell adhesion proteins (CAPs), and proteoglycans. CAPs act like glue to hold the tissue together. The proteoglycans are composed of a protein coreand glycosaminoglycans (GAGs). GAGs are composed of chondroitin and hyaluronic acid which is a large unbranched polysaccharide that makes some connective tissue very viscous and slippery.Lecture 10 (September 22 nd ):Discuss the structure, function, and location of the different types of fibrous connective tissues. Fibrous connective tissue can be classified into loose connective tissue and dense connective tissue. Loose connective tissue is typically vascular and innervated. It’s mainly composed of fibroblasts, fibrocytes, and a few fibroclasts. Areolar connective tissue is a type of loose CT that is composed of collagen, elastin, and reticular fibers loosely arranged in the EM. Areolar CT is fairly widespread throughout the body, but specifically