THE TISSUE LEVEL OF ORGANIZATIONA. TYPES OF TISSUESList three characteristics of a tissue?1. Group of similar cells AND their extracellular matrices2. Share a common embryological origin3. Function together as a group to carry out particular functionsWhat determines the functions and properties of a tissue?The functions and properties of a tissue are determined by the nature of the cells and the extracellular matrix, if present, created by and surrounding the cells.List the four basic tissue types and give a brief description of each.1. Epithelial tissues – cover the body surfaces; line hollow organs, body cavities, and ducts; form glands2. Connective tissues – protect and support the body and its organs; binds organs together; store energy reserves as fat; provide resistance to disease in association with the immune system3. Muscular tissues – responsible for movement and generation of force4. Nervous tissue – initiate and transmit action potentials (nerve impulses) that help coordinate body activitiesB. EPITHELIAL TISSUES1. GENERAL FEATURESDescribe the general features of epithelial tissues.1. Closely packed cells with little or no extracellular material between them2. Cells arranged into continuous sheets, in either single or multiple layers3. Epithelial cells have an apical surface that is exposed to a body cavity, lining of an internal organ, or the exterior of the body.4. Epithelial cells have a basal surface that is attached to a basement membrane295. The basement membrane (basal lamina) is a connective tissue matrix that attaches the overlying epithelium to the underlying connective tissue6. Epithelia are avascular, meaning that they have no blood supply. They receive their nutrition by diffusion from the underlying connective tissues.7. Epithelial have a nerve supply.8. Since epithelia are subject to a certain amount of wear, tear, and injury, they have a high capacity for mitosis.2. COVERING AND LINING EPITHELIAa. ARRANGEMENT OF LAYERSb. CELL SHAPESc. CLASSIFICATIONCovering and lining epithelia are arranged into continuous sheets ofcells consisting of one of three layer types depending upon the function of the tissue.Covering and lining epithelia are also classified according to the shape of the cells that lie on the apical surface of the epithelium.Describe the following:1. simple epithelium – If the function is absorption or filtration, or the tissue is in an area of minimal wear and tear, the cells form a single layer, and is thus called a simple epithelium.2. stratified epithelium – If the tissue is in an area with a high degree of wear and tear, then the cells are stacked into layers, and is thus called a stratified epithelium3. pseudostratified epithelium – A third less common arrange-ment is the pseudostratified epithelium that has a single layer of cells, so it is simple, but some cells do not reach the apical surface, giving it a multilayered appearance.Describe each of the following:1. squamous cells – squamous cells are flattened and scale-like2. cuboidal cells – cuboidal cells are usually cube-shaped in cross-section, being roughly as tall as they are wide3. columnar cells – columnar cells are tall and cylindrical or somewhat rectangular, and generally taller than they are wide304. transitional cells – Transitional cells readily change shape and are found where there is a continuous amount of stretching then relaxation, such as in the urinary bladder. The apical layer may range from squamous to cuboidal.d. PHOTOMICROGRAPHStissue location(s) description function(s)simple squamous lining heart (endocardium) and blood vessels (endothelium), lymphatic vessels, alveoli of lungs, glomerular capsule of kidneys, part of serous membranesconsists of a single layer of flattened, scale-like cells, much like a tile floordiffusion, osmosis, and filtrationstratified squamouskeratinized form forms epidermis; nonkeratinized forms line mouth and tongue, pharynx, esophagus, anal canal, and vaginaconsists of multiple layers flattened on surface; cuboidal to columnar in deepest layersprotection against wear-and-tearsimple cuboidal lines kidney tubules and smallducts of many glands, covers ovary, forms pigmented epithelium of retinaconsists of a single layer of cube-shaped cells, about as tall as they are wideabsorption and secretionstratified cuboidal relatively rare; lines larger ducts of some glands and part of the male urethraconsists of two or more layers of cells, the uppermost being cuboidal in shapeprotectionsimple columnar lines GI tract from stomach toanal canal, ducts of some glands, gallbladder; ciliated form lines oviducts, uterus, central canal of spinal cordsingle layer of rectangular (columnar) cells, often has interspersed goblet cellssecretion and absorptionpseudostratified lines much of lower respiratory system down to bronchiolar level; nonciliated form may be found in some gland ducts, epididymis, and part of male urethranot truly stratified; all cells contact basement membrane, but not all reach apical; surfacesecretion from goblet cells, movement of mucous across surface by ciliary actiontransitional urinary bladder, portions of ureters and urethravariable; apical cells vary from squamous to cuboidal depending on degree of stretch of organallows distention of organ without causing an increase in tension inwall of organ3. GLANDULAR EPITHELIAGlandular epithelium forms the secretory portions of glands. Name the two major types of glands in the body and give a brief description of each.1. Endocrine glands – endocrine glands are ductless; secrete hormones into the blood312. Exocrine glands – exocrine glands secrete their product(s) either onto the apical surfaces of the cells or into ducts for transport to the free surface.a. STRUCTURAL CLASSIFICATIONList the two major structural classifications of exocrine glands and give a brief description of each.1. Unicellular glands – The best example of a unicellular gland is the goblet cell. This single cell secretes its product directly onto the free surface of many epithelia.2. Multicellular glands – A multicellular gland consists of a secreting organ found deep to the free surface and attached to it via a duct.b. FUNCTIONAL CLASSIFICATIONWhat is the basis for the functional classification of glands?Functional classification is based on whether a secretion is aproduct of a cell or consists of entire or partial glandular cellsthemselves.Describe each of the following:1. holocrine