CHAPTER 3 Cells and Tissues
Body Tissues 3 -14 Name the 4 major tissue types and their chief subcategories. Explain how the four major tissue types differ structurally and functionally. Tissues: groups of cells that are similar in structure and function
Body Tissues - Four major tissue types: epithelium - - connective - - support nervous - - covering control muscle - movement
Body Tissues Epithelial Tissues Poster Project 1. Title: Insert your category of epithelial tissue here 2. Labeled drawing of your tissue type 3. Example of where it’s located in the body 4. Describe the structure and function(s) Refer to textbook pgs. 88 -92 You can also use online rescources *Posters should be neat, colorful, and visually appealing *Information should be large and clear enough to
Body Tissues Epithelial Tissue (epithelium) (epithe = laid on, covering) is the lining, covering, and glandular tissue of the body -
Body Tissues Glandular epithelium forms various glands in the body. Covering and lining epithelium covers all free body surfaces and contains versatile cells � One type forms the epidermis (outer layer of the skin) � Others dip into the body to line its cavities
Body Tissues Nearly all substances that the body gives off or receives must pass through the epithelium. Epithelial functions: - protection - absorption - filtration - secretion
Body Tissues Special Characteristics of Epithelium -Except for glandular epithelium, epithelial cells fit closely together to form continuous sheets. Neighboring cells held together at multiple points by specialized cell junctions -The membranes always have one free (unattached) surface or edge, the apical surface, which is exposed to the body’s exterior or to the cavity of an internal organ.
Body Tissues Special Characteristics of Epithelium, continued - the lower surface of an epithelium rests on a basement membrane, a structureless material secreted by both the epithelial cells and the connective tissue cells that abut the epithelium - - epithelial tissues are avascular and therefore depend on diffusion from the capillaries in underlying connective tissue for food and oxygen epithelial cells regenerate easily if well nourished
Body Tissues Classification of Epithelium Each epithelium is given two names. The first indicates the number of layers: simple = single layer stratified = multiple layers The second describes the shape of the cells: squamous = flattened cuboidal = cube-shaped columnar = column-shaped
Body Tissues Simple Epithelia Primary functions (physiology): absorption, secretion, filtration Structure (anatomy): single layer, therefore very thin The very thin structure allows simple epithelia to perform their functions. Due to being so thin, protection is not one of their specialties.
Body Tissues (see worksheet!) Simple Squamous Epithelium Structure: single layer of thin squamous cells resting on a basement membrane. The cells fit closely together like floor tiles. Function: filtration and rapid diffusion, also forms serous membranes that line the ventral cavity and cover the organs in the cavity Locations: in the air sacs of the lungs, walls of
Body Tissues (see worksheet!) Simple Cuboidal Epithelium Structure: one layer of cuboidal cells resting on a basement membrane Functions: Secretion and absorption; ciliated types propel mucus or reproductive cells Locations: in glands and their ducts. For example, the salivary glands and pancreas. Also forms walls of the kidney tubules and covers the surface of the ovaries.
Body Tissues (see worksheet!) Simple Columnar Epithelium Structure: single layer of tall cells that fit closely together. Often this tissue also contains goblet cells which produce a lubricating mucus. Functions: Secretion and absorption; ciliated types propel mucus or reproductive cells Locations: line the digestive tract from stomach to anus. The epithelial membranes that line body cavities open to the body exterior are called mucosae, or mucus membranes.
Body Tissues (see worksheet!) Pseudostratified Columnar Epithelium Structure: a layer of tall cells that have their nuclei at varying heights which gives the appearance of multiple layers, but it’s not really stratified (pseudo = false) Functions: absorption and secretion Locations: male urethra; a ciliated variety is present in the lungs and trachea
Body Tissues Stratified Epithelia Primary function: protection Structure: two or more cell layers The thickness of multiple cell layers makes this tissue considerably more durable that the simple epithelia, which makes it more well-suited for it’s protective function.
Body Tissues (see worksheet!) Stratified Squamous Epithelium Structure: consists of several layers of cells. Cells at the free edge are squamous cells; those close to the basement membrane are cuboidal or columnar Function: protect areas from impact and friction Locations: mouth, esophagus, and the outer portion of the skin
Body Tissues (see worksheet!) Stratified Cuboidal and Stratified Columnar Epithelia Structure: Cuboidal – typically has just 2 cell layers with (at least) the surface cells being cuboidal Columnar – surface cells are columnar, but its basal cells vary in size and shape Function: protection Locations: (rare in humans) found mainly in the ducts
Body Tissues (see worksheet!) Transitional Epithelium Structure: several layers of cells; basal cells are columnar or cuboidal; surface cells are rounded and dome like, but able to slide past one another and change their shape to flattened, more squamous-like cells Function: allows organs to temporarily enlarge, and then return to their original size Location: lining of the bladder, ureters, and part of the urethra (all part of the urinary system and subject to considerable stretching)
Body Tissues (see worksheet!) Glandular Epithelium Structure: one or more cells that make up a gland Function: secretion Location: various endocrine and exocrine glands throughout the body.
Check for understanding: 1. What two criteria are used to classify epithelial tissues? number of cell layers and shape of cells 2. Which of the following properties apply to epithelial tissues? Has blood vessels, can repair itself, has specialized cell junctions can repair itself and has specialized cell junctions 3. Which epithelial tissue’s primary functions are diffusion and filtration? simple squamous epithelium