Chapter 4 Tissues: Living Communities

Introduction Since cells are differentiated, they have lost ability to perform all metabolic functions required to sustain life as an isolated entity. Cells exist in cooperative communities in multicellular organisms Cells of similar type and function cluster together to form _____________. Tissues cluster to form organs.

Classification of Tissues Epithelial tissue Covers and lines Connective tissue Provides support Muscle tissue Enables movement Nervous tissue Controls work Most organs contain all 4 tissue types. The study of microscopic structures of tissues and organs is called _________

Epithelial Tissue Composed of sheets of cells that cover and line other tissues. Lines bladder, mouth, blood vessels, thorax, etc. Have an exposed surface that affords access to the surrounding environment or to the inner openings of chambers and ducts. Functions: ____________, covers, lines ____________ of biochemical substances May be _____________ May play an important role in ____________ input ____________ and ____________ of biochemical substances Glandular epithelia Individual glandular epithelial cells are goblet cells, groups are referred to as glands.

Characteristics of Epithelia Organized into tightly packed groups that form _________ of tissue. Can be composed of single layer or multiple layers depending on _________. Epithelial cells share the following characteristics: ________ - Each epithelial cell has an apical surface and a basal surface Apical surface faces the lumen or body cavity Basal surface faces the underlying connective tissue Lateral surfaces are connected to neighboring cells by ________________ complexes Epithelial cells are avascular Rely on underlying connective tissue for oxygen and nutrients Most epithelial cells are innervated

Between the cell membranes of adjacent epithelial cells are channels that carry nutrients to the cells and wastes away from them. Junctional Complexes – specialized attachments between epithelial cells at their plasma membranes. Give epithelial tissue strength. Tight junctions Nothing can penetrate Prevent ____________ Bladder, GI tract Desmosomes Welded plaque Tough, resist __________ and stretching (like Velcro). Consist of intermediate fibers (tonofilaments) Skin, heart, uterus Gap junctions Cytoplasm continuous Linked by tubular channel proteins called _______________. Allow exchange of ions, nutrients, and transport signals Cardiac, smooth muscles

Epithelial Cells: Basement Membrane Foundation of epithelial cells and made by epithelial cells Meshwork of fibers that cements epithelial cell to underlying _____________________ tissue (CT) Its strength and elasticity help to prevent the epithelial cell from being torn away Also called basal _________ Varies in thickness Oxygen and nutrients diffuse through the basement membrane from the connective tissue. Absorbed substances and waste products produced by epithelium diffuse through basement membrane to the connective tissue.

Surface Specialization Surfaces vary depending on location in body and function May be smooth or contain ___________(fingerlike projections) or _______(hairs) 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 surface area, which aids in absorption. (can add up to 20 times of surface area). Epithelial cells of the skin are filled with a waterproof called __________. Accumulate as cell matures

Classifications of Epithelia Classified according to 3 characteristics: Number of cell layers. Single layer is called __________ Found in protected parts of body where they provide minimal protection to underlying structures More than one layer is called __________ Thicker and stronger and are on parts of body that are subjected to mechanical or chemical stress. 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 Fragile and thin Flat and smooth; reduce friction Found lining surfaces involved in the passage of either _____ or ________ lining of lungs, kidneys ______thelium – lining of chest (pleura), abdomen (peritoneum), and pericardium ______thelium – lining of blood vessels

Simple Cuboidal Epithelium Single layer of cubical cells Round, dark-staining nuclei aligned in a single ______ Occurs in areas of the body where ___________ and ______________ take place Surface of ovaries, glands, lining of ducts of liver, kidneys, pancreas Found throughout the ____________ system

Simple Columnar Epithelium Elongated and closely packed together – thick and protective Nuclei aligned in a row (not central) at the base of the cell near the basement membrane Also found in areas of absorption and secretion Line the _____ tract from stomach to rectum ____________ cell- apical surface is blanketed by dense microvilli that maximize absorption by increasing surface contact with nutrient-filled lumen. __________ cell- manufacture and store mucus for lubrication Also found in many excretory ducts ________ in respiratory tract and uterus

Stratified Squamous Epithelium Multilayered Continually being _____ away or __________ off Replaced by cells from deeper layers _________ 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 Occur in areas of the body subject to __________ and ___________ stresses Mouth, esophagus, vagina, rectum Skin (keratinized)

Stratified Cuboidal Epithelium Usually ______ layers of cuboidal cells Provides protection to deeper, delicate tissues Found primarily along large excretory ducts Salivary glands, mammary glands, sweat glands

Rare Basal cells are _________ Function in secretion and protection Found only in select parts of the respiratory, digestive, reproductive systems and along some excretory ducts Stratified Columnar Epithelium

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. Found in respiratory tract and in portions of male reproductive tract

Transitional Epithelium Stratified epithelium Basal layer of cuboidal or columnar cells Superficial layer of cuboidal or squamous cells Ability to _______ - found in areas where changes in volume occur __________ tract As epithelia stretches, layers often thin depending on how much volume is present Forms a _____-proof barrier