THE TISSUE LEVEL OF ORGANIZATION A TYPES OF TISSUES List three characteristics of a tissue 1 2 3 Group of similar cells AND their extracellular matrices Share a common embryological origin Function together as a group to carry out particular functions What 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 B 1 Epithelial tissues cover the body surfaces line hollow organs body cavities and ducts form glands 2 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 system 3 Muscular tissues responsible for movement and generation of force 4 Nervous tissue initiate and transmit action potentials nerve impulses that help coordinate body activities EPITHELIAL TISSUES 1 GENERAL FEATURES Describe the general features of epithelial tissues 1 2 3 4 Closely packed cells with little or no extracellular material between them Cells arranged into continuous sheets in either single or multiple layers Epithelial cells have an apical surface that is exposed to a body cavity lining of an internal organ or the exterior of the body Epithelial cells have a basal surface that is attached to a basement membrane 29 5 6 7 8 2 The basement membrane basal lamina is a connective tissue matrix that attaches the overlying epithelium to the underlying connective tissue Epithelia are avascular meaning that they have no blood supply They receive their nutrition by diffusion from the underlying connective tissues Epithelial have a nerve supply Since epithelia are subject to a certain amount of wear tear and injury they have a high capacity for mitosis COVERING AND LINING EPITHELIA a ARRANGEMENT OF LAYERS b CELL SHAPES c CLASSIFICATION Covering and lining epithelia are arranged into continuous sheets of cells 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 epithelium 3 pseudostratified epithelium A third less common arrangement 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 scalelike 2 cuboidal cells cuboidal cells are usually cube shaped in cross section being roughly as tall as they are wide 3 columnar cells columnar cells are tall and cylindrical or somewhat rectangular and generally taller than they are wide 30 4 d 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 PHOTOMICROGRAPHS tissue 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 membranes keratinized form forms epidermis nonkeratinized forms line mouth and tongue pharynx esophagus anal canal and vagina lines kidney tubules and small ducts of many glands covers ovary forms pigmented epithelium of retina relatively rare lines larger ducts of some glands and part of the male urethra consists of a single layer of flattened scalelike cells much like a tile floor diffusion osmosis and filtration consists of multiple layers flattened on surface cuboidal to columnar in deepest layers consists of a single layer of cube shaped cells about as tall as they are wide consists of two or more layers of cells the upper most being cuboidal in shape single layer of rectangular columnar cells often has interspersed goblet cells protection against wearand tear not truly stratified all cells contact basement membrane but not all reach apical surface secretion from goblet cells movement of mucous across surface by ciliary action variable apical cells vary from squamous to cuboidal depending on degree of stretch of organ allows distention of organ without causing an increase in tension in wall of organ stratified squamous simple cuboidal stratified cuboidal simple columnar pseudostratified transitional 3 lines GI tract from stomach to anal canal ducts of some glands gallbladder ciliated form lines oviducts uterus central canal of spinal cord lines much of lower respiratory system down to bronchiolar level nonciliated form may be found in some gland ducts epididymis and part of male urethra urinary bladder portions of ureters and urethra absorption and secretion protection secretion and absorption GLANDULAR EPITHELIA Glandular 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 blood 31 2 a 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 STRUCTURAL CLASSIFICATION List the two major structural classifications of exocrine glands and give a brief description of each b 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 FUNCTIONAL CLASSIFICATION What is the basis for the functional classification of glands Functional classification is based on whether a secretion is a product of a cell or consists of entire or partial glandular cells themselves Describe each of the following 1 holocrine secretion In holocrine secretion the cells accumulate secretory product in their cytosol die and are discharged with their