Tissues Living Communities Chapter 4 Cells of similar

Tissues: Living Communities Chapter 4

Cells of similar ______ and _______ cluster together to form tissues. Epithelial tissue Covers and lines Connective tissue Provides support Muscle tissue Enables movement Nervous tissue Controls work The study of microscopic structures of tissues and organs is

Characteristics of Epithelia Sheets of cells that cover and line other tissues. Covers the surface of organs and also lines the lumen of hollow organs. Lines bladder, blood vessels, thorax, etc. Can be composed of single layer or multiple layers depending on location. ____ - Each epithelial cell has an apical surface and a basal surface Apical surfaces the lumen or environment Basal surfaces the underlying connective tissue All epithelial cells are _______. Rely on underlying connective tissue for oxygen and nutrients

Junctional Complexes – specialized attachments between epithelial cells on their lateral surfaces. They connect via plasma membranes. Tight junctions Prevent ______ Ex: Bladder Desmosomes Tough, resist _____ and stretching (like Velcro). Consist of intermediate fibers Ex: Uterus Gap junctions Cytoplasm continuous between cells Linked by tubular channel proteins called ________. Allow exchange of ions, nutrients, and transport signals Ex: Cardiac muscle

Epithelial Cells: Basement Membrane Foundation of epithelial cells Meshwork of fibers that cements epithelial cell to underlying __________ tissue (CT) Helps to prevent the epithelial cell from being torn away Also called basal _____ Oxygen and nutrients diffuse up to epithelium through the basement membrane from the connective tissue. Absorbed substances and waste products produced by epithelium diffuse down through

Surfaces vary depending on location in body and function May be smooth or contain _______ or _______ Cilia found in respiratory and reproductive tracts. Microvilli in intestines and urinary tract. If the cell contains microvilli, it is said to have a _____ border. Brush border helps to increase _______ area, which aids in absorption. (can add up to 20 times the surface area). Epithelial cells of the skin are filled with a waterproof protein called _____. Accumulates as cell matures. Surface Specialization

Classifications of Epithelia Number of cell layers. Single layer is called _____ More than one layer is called _____ Shape of cells Based on shape that is on exposed or _____ surface Squamous, cuboidal, and columnar Presence of surface specializations Keratinized, ciliated, etc.

Simple Squamous Epithelium Flat and smooth; reduce friction Often found lining surfaces involved in the passage of either _____ or ____ ENDOTHELIUM, KIDNEYS, ALVEOLI OF LUNGS

Simple Cuboidal Epithelium Round, dark-staining nuclei aligned in a single row GLANDS (endocrine and exocrine): salivary glands, ovaries, liver, kidneys, pancreas

Simple Columnar Epithelium Elongated cells with elongated nuclei aligned in a row at the base of the cell Line DIGESTIVE TRACT from stomach to rectum ______ cell- apical surface is blanketed by microvilli that maximize absorption by increasing surface contact with nutrient-filled lumen. _____ cell- manufacture and store mucin (component of mucus) for lubrication

Stratified Squamous Epithelium Multilayered Continually worn away or sloughed off Cuboidal cells are attached to the basement membrane. As they mature, they are pushed to the surface away from nutrients. Lose their cytoplasm and nuclei and become squamous. MOUTH, VAGINA, RECTUM, SKIN (keratinized) Areas of the body that encounter mechanical stresses)

Pseudostratified Columnar Epithelium “_______” stratified – truly simple epithelium Cell nuclei are found at different levels across the length of the tissue Some cells do not reach luminal surface, but ALL attach to basement membrane. Usually ____ and often associated with ______ cells.

Transitional Epithelium Stratified epithelium Basal layer of cuboidal or columnar cells Superficial layer of cuboidal cells (domelike) Ability to _______ URINARY TRACT leak-proof As epithelia stretches, layers often thin depending on how much volume is present

Gland- cells that have the ability to manufacture and discharge a secretion. _______- specialized protein molecules that are produced in the RER, packaged by the golgi and discharged from the cell. Glandular epithelial cells have prominent ER, Golgi Secretions may be sent far away in the body for use. Multicellular glands form in utero A layer of epithelial cells folds inward (______). Form _____ that lead to the epithelial surface Some glands (_____) lose the duct and become separated from the original epithelium Glandular Epithelia

Glands can be classified by the following factors: Presence or absence of ducts Endocrine vs. Exocrine Number of cells that compose them Unicellular vs multicellular Shape of secreting ducts Simple or compound Complexity of glandular structure Tubular, acinar, tubuloacinar Type of secretion made Mucoid or serous Manner in which secretion is stored and discharged Merocrine, apocrine, or holocrine

NO DUCTS (cells die) Produce and secrete _______. Blood stream delivers secretions to entire body ______ within the gland bring secretions to the circulatory system Endocrine Glands

Contain ducts (except for ____ cells) Have local effect. Discharge secretions via ducts directly into nearby areas. Secretions act locally and do not enter into the circulatory system Examples of secretions: Saliva Bile Pancreatic and liver digestive enzymes Sweat Egg/Sperm Exocrine Glands

Unicellular Exocrine Gland: Only unicellular exocrine gland Goblet Cell _____less Composed of a modified ______ epithelial cell. Found interspersed among the columnar cells of the respiratory and digestive tracts and conjunctiva of eye Secretes _______: (polysaccharides, proteins, and glycoproteins) when mixed with water → mucus Mucus functions to protect and lubricate the apical surface of the

Multicellular Exocrine Glands Contain 2 distinct components: 1) ______ Unit Secretory cells usually surrounded by connective tissue rich in blood vessels and nerve fibers that provides nourishment and structural support to the unit. 2) ____ carries secretion to its deposit site _____epithelial cells may be present that assist with the discharge of secretions into the glandular duct. Rate of secretion production is controlled by hormonal and nervous influences.

Classification of Multicellular Exocrine Glands: Shape Based on shape and number of tubes If main duct is unbranched, the gland is ____ If main duct is branched, gland is _____ If secretory cells form a long channel of even width, gland is _____ If cells form a rounded sac, it is _____ or acinar Glands with both tubular and alveolar qualities are tubuloalveolar or tubuloacinar

Classification of Exocrine Glands: Manner of secretion How much of a cell is sacrificed in the act of secretion determines its classification: ________ Glands package their secretions and release them via exocytosis as they are manufactured Secretory cells remain intact Majority of glands ________ Glands store their secretions in the apex of the secretory cell after they are manufactured. When apex is full, it is pinched off and released with the secretions into the duct system. Cell is repaired and process is repeated. ________ Glands store their secretions until they are needed. The cell lyses, releasing its contents. Cell dies and is