Human Anatomy and Physiology Eleventh Edition PDF

Human Anatomy and Physiology Eleventh Edition Chapter 04 Part A Tissue: The Living Fabric PowerPoint® Lectures Slides prepared by Karen Dunbar Kareiva, Ivy Tech Community Colle...

Human Anatomy and Physiology Eleventh Edition Chapter 04 Part A Tissue: The Living Fabric PowerPoint® Lectures Slides prepared by Karen Dunbar Kareiva, Ivy Tech Community College Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Tissue: The Living Fabric Individual body cells are specialized – Each type performs specific functions that maintain homeostasis Tissues – Groups of cells similar in structure that perform common or related function Histology – Study of tissues Four basic tissue types: epithelial, connective, muscle, and nervous tissue Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Overview of Four Basic Tissue Types: Epithelial, Connective, Muscle, and Nervous Tissues Nervous tissue: Internal communication Brain Spinal cord Nerves Muscle tissue: Contracts to cause movement Muscles attached to bones (skeletal) Muscles of heart (cardiac) Muscles of walls of hollow organs (smooth) Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters Lining of digestive tract organs and other hollow organs Glands (e.g., pancreas) Skin surface (epidermis) Connective tissue: Supports, protects, binds other tissues together Bones Tendons Fat and other soft padding tissue Figure 4.1 Overview of four basic tissue types: epithelial, connective, muscle, and nervous tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 4.1 Microscopy of Human Tissue To be viewed under a microscope, tissue must be: – Fixed: tissue is preserved with solvent – Sectioned: cut into slices thin enough to transmit light or electrons – Stained: to enhance contrast, although artifacts (distortions) detract from what the sample looks like in living tissues ▪ Light microscopy uses colored dyes ▪ Electron microscopy uses heavy metal coatings Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Comparison of Transmission and Electron Micrographs Transmission micrograph Scanning electron micrograph Figure 4.2 Comparison of transmission and scanning electron micrographs. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 4.2 Epithelial Tissue Epithelial tissue (epithelium) is a sheet of cells that covers body surfaces or cavities Two main forms: – Covering and lining epithelia ▪ On external and internal surfaces (example: skin) – Glandular epithelia ▪ Secretory tissue in glands (example: salivary glands) Main functions: protection, absorption, filtration, excretion, secretion, and sensory reception Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Special Characteristics of Epithelial Tissues Epithelial tissue has five distinguishing characteristics: 1. Polarity 2. Specialized contacts 3. Supported by connective tissues 4. Avascular, but innervated 5. Regeneration Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Special Characteristics of Epithelial Tissues Polarity – Cells have polarity (top and bottom) – Apical surface, upper free side, is exposed to surface or cavity ▪ Most apical surfaces are smooth, but some have specialized fingerlike projections called microvilli – Basal surface, lower attached side, faces inwards toward body ▪ Attaches to basal lamina, an adhesive sheet that holds basal surface of epithelial cells to underlying cells – Both surfaces differ in structure and function Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Special Characteristics of Epithelial Tissues Plasma membranes Microvilli of adjacent cells Specialized contacts – Epithelial tissues need to fit closely together Space between ▪ Many form cells continuous sheets – Specialized contact points bind adjacent epithelial Extracellular matrix cells together ▪ Lateral contacts include: – Tight junctions Interlocking – Desmosomes junctional proteins Space between cells (a) Tight junctions Impermeable junctions Form continuous seals around the cell Prevent molecules from passing between cells Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Cell Junctions Plasma membranes Microvilli of adjacent cells Space between cells Extracellular matrix Space between cells Plaque Linker Proteins Intermediate filament (cadherins) (keratin) (b) Desmosomes Anchoring junctions Bind adjacent cells together like Figure 3.4b Cell junctions. molecular Velcro® Help keep cells from tearing apart Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Special Characteristics of Epithelial Tissues Supported by connective tissues – All epithelial sheets are supported by connective tissue – Reticular lamina ▪ Deep to basal lamina ▪ Consists of network of collagen fibers – Basement membrane ▪ Made up of basal and reticular lamina ▪ Reinforces epithelial sheet ▪ Resists stretching and tearing ▪ Defines epithelial boundary Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Clinical – Homeostatic Imbalance 4.1 Cancerous epithelial cells are not contained by the basement membrane boundary like other cells They penetrate the boundary and invade underlying tissues, resulting in spread of cancer Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Special Characteristics of Epithelial Tissues Avascular, but innervated – No blood vessels are found in epithelial tissue ▪ Must be nourished by diffusion from underlying connective tissues – Epithelia are supplied by nerve fibers, however Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Special Characteristics of Epithelial Tissues Regeneration – Epithelial cells have high regenerative capacities – Stimulated by loss of apical-basal polarity and broken lateral contacts – Some cells are exposed to friction, some to hostile substances, resulting in damage ▪ Must be replaced ▪ Requires adequate nutrients and cell division Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia All epithelial tissues have two names – First name indicates number of cell layers ▪ Simple epithelia are a single layer thick ▪ Stratified epithelia are two or more layers thick and involved in protection (example: skin) – Second name indicates shape of cells ▪ Squamous: flattened and scale-like ▪ Cuboidal: box-like, cube ▪ Columnar: tall, column-like – In stratified epithelia, shape can vary in each layer, so cell is named according to the shape in apical layer Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia (a) Classification based on number of cell layers Apical surface Basal surface Simple Apical surface Basal surface Stratified Figure 4.3a Classification of epithelia. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia Note: nucleus shape conforms to cell shape (b) Classification based on cell shape Squamous Cuboidal Columnar Figure 4.3b Classification of epithelia. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia Simple epithelia – Involved in absorption, secretion, or filtration processes – Very thin layer ideal for diffusion but not for protection – Simple squamous epithelium ▪ Cells are flattened laterally, and cytoplasm is sparse ▪ Function where rapid diffusion is priority – Example: kidney, lungs ▪ Two specially named simple squamous epithelia are based on locations – Endothelium (“inner covering”): lining of lymphatic vessels, blood vessels, and heart – Mesothelium (“middle covering”): serous membranes in the ventral body cavity, lungs, and covering organs Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Epithelium: Simple Squamous (a) Epithelium: simple squamous Description: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia. Air sacs of lung tissue Nuclei of squamous Function: Allows materials to pass by diffusion and filtration in sites where protection epithelial is not important; secretes lubricating cells substances in serosae (linings of ventral body cavity). Location: Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; serosae. Photomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (140×). Figure 4.4a Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia Simple cuboidal epithelium – Single layer of cells, as tall as they are wide – Involved in secretion and absorption – Forms walls of smallest ducts of glands and many kidney tubules Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Epithelium: Simple Cuboidal (b) Epithelium: simple cuboidal Description: Single layer of cubelike cells with large, spherical central nuclei. Simple cuboidal epithelial cells Nucleus Function: Secretion and absorption. Basement Location: Kidney tubules; ducts and secretory membrane portions of small glands; ovary surface. Connective tissue Photomicrograph: Simple cuboidal epithelium in kidney tubules (430×). Figure 4.4b Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia Simple columnar epithelium – Single layer of tall, closely packed cells ▪ Some cells have microvilli, and some have cilia ▪ Some layers contain mucus-secreting goblet cells – Involved in absorption and secretion of mucus, enzymes, and other substances ▪ Ciliated cells move mucus – Found in digestive tract, gallbladder, ducts of some glands, bronchi, and uterine tubes Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Epithelium: Simple Columnar (c) Epithelium: simple columnar Description: Single layer of tall cells with round to oval nuclei; many cells bear microvilli, some bear cilia; layer may contain mucus- secreting unicellular glands (goblet cells). Cavity inside intestine Microvilli (on apical surfaces) Simple columnar Function: Absorption; secretion of mucus, epithelial enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by cells ciliary action. Location: Nonciliated type lines most of the Mucus of digestive tract (stomach to rectum), goblet cell gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus. Photomicrograph: Simple columnar epithelium of the small intestine mucosa (640×). Figure 4.4c Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia Pseudostratified columnar epithelium – Cells vary in height and appear to be multi-layered and stratified, but tissue is in fact single-layered simple epithelium ▪ “Pseudo” means false ▪ Many cells are ciliated – Involved in secretion, particularly of mucus, and also in movement of mucus via ciliary sweeping action – Located mostly in upper respiratory tract, ducts of large glands, and tubules in testes Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Epithelium: Pseudostratified Columnar (d) Epithelium: pseudostratified columnar Description: Single layer of cells of differing heights, some not reaching the free surface; Goblet cell nuclei seen at different levels; may contain mucus-secreting cells and bear cilia. (contains mucus) Cilia Pseudo- Function: Secrete substances, particularly stratified mucus; propulsion of mucus by ciliary action. epithelial layer Location: Ciliated variety lines the trachea and most of the upper respiratory tract; nonciliated type in males’ sperm-carrying ducts and ducts of large glands. Basement membrane Trachea Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (780×). Figure 4.4d Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia Stratified epithelial tissues – Involve two or more layers of cells – New cells regenerate from below ▪ Basal cells divide and migrate toward surface – More durable than simple epithelia because protection is the major role – Stratified squamous epithelium ▪ Most widespread of stratified epithelia ▪ Free surface is squamous, with deeper cuboidal or columnar layers ▪ Located in areas of high wear and tear (example: skin) ▪ Keratinized cells found in skin; nonkeratinized cells are found in moist linings Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Epithelium: Stratified Squamous (e) Epithelium: stratified squamous Description: Thick epithelium composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers. Stratified squamous epithelium Function: Protects underlying tissues in areas subjected to abrasion. Location: Nonkeratinized type forms the Nuclei moist linings of the esophagus, mouth, and vagina; keratinized variety forms the Basement epidermis of the skin, a dry epithelium. membrane Connective tissue Photomicrograph: Stratified squamous epithelium lining the esophagus (285×). Figure 4.4e Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia Stratified epithelial tissues (cont.) – Stratified cuboidal epithelium ▪ Quite rare ▪ Found in some sweat and mammary glands ▪ Typically only two cell layers thick – Stratified columnar epithelium ▪ Also very limited distribution in body ▪ Small amounts found in pharynx, in male urethra, and lining some glandular ducts ▪ Usually occurs at transition areas between two other types of epithelia ▪ Only apical layer is columnar Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Epithelia Stratified epithelial tissues (cont.) – Transitional epithelium ▪ Forms lining of hollow urinary organs – Found in bladder, ureters, and urethra ▪ Basal layer cells are cuboidal or columnar ▪ Ability of cells to change shape, undergo “transitions”, when stretched allows for increased flow of urine and, in the case of bladder, more storage space Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Epithelium: Transitional (f) Epithelium: transitional Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch. Transitional epithelium Function: Stretches readily, permits stored urine to distend urinary organ. Location: Lines the ureters, bladder, and part of the urethra. Basement membrane Connective tissue Photomicrograph: Transitional epithelium lining the bladder, relaxed state (360×); note the bulbous, or rounded, appearance of the cells at the surface; these cells flatten and elongate when the bladder fills with urine. Figure 4.4f Epithelial tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Concept review All of the following are examples of distinguishing characteristics of epithelial tissue except: A) the existence of both an apical and basal surface B) the existence of tight junctions between cells C) the underlying connection to nervous tissue D) the ability to replace damaged cells with new health cells E) all of the above are examples of distinguishing characteristics of epithelial tissue Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Glandular Epithelia Gland – One or more cells that makes and secretes an aqueous fluid called a secretion Classified by: – Site of product release: ▪ Endocrine: internally secreting (example: hormones) ▪ Exocrine: externally secreting (example: sweat) – Relative number of cells forming the gland ▪ Unicellular (example: goblet cells) or multicellular (example: salivary) Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Formation of Multicellular Exocrine and Endocrine Glands Multicellular epithelial glands Exocrine glands retain the Endocrine glands lose their ducts during form by invagination (inward connecting cells, which form a development. They secrete hormones growth) of an epithelial sheet. duct that transports secretions into the interstitial fluid. These to the epithelial surface. hormones then enter the blood. Epithelial sheet Connecting cells Duct cell are lost during development Endocrine Invaginated Exocrine gland cell epithelial sheet gland cell Blood vessel Figure 4.5 Formation of multicellular exocrine and endocrine glands. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Glandular Epithelia Endocrine glands – Ductless glands ▪ Secretions are not released into a duct; are released into surrounding interstitial fluid, which is picked up by circulatory system – Secrete (by exocytosis) hormones, messenger chemicals that travel through lymph or blood to their specific target organs – Target organs respond in some characteristic way Endocrine glands lose their ducts during development. They secrete hormones into the interstitial fluid. These hormones then enter the blood. Connecting cells are lost during development Endocrine gland cell Blood vessel Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Glandular Epithelia Exocrine glands – Secretions are released onto body surfaces, such as skin, or into body cavities – More numerous than endocrine glands – Secrete products into ducts – Examples include mucous, sweat, oil, and salivary glands – Can be: ▪ Unicellular Exocrine glands retain the connecting cells, which form a ▪ Multicellular duct that transports secretions to the epithelial surface. Duct cell Exocrine gland cell Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Glandular Epithelia Unicellular exocrine glands – The only important unicellular glands are mucous cells and goblet cells – Found in epithelial linings of intestinal and respiratory tracts – All produce mucin, a sugar-protein that can dissolve in water to form mucus, a slimy protective, lubricating coating Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Goblet Cell (Unicellular Exocrine Gland) Microvilli Secretory vesicles containing mucin Golgi apparatus Rough ER Nucleus (a) (b) Figure 4.6 Goblet cell (unicellular exocrine gland). Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Glandular Epithelia Multicellular exocrine glands – Multicellular exocrine glands are composed of a duct and a secretory unit – Usually surrounded by supportive connective tissue that supplies blood and nerve fibers to gland ▪ Connective tissue can form capsule around gland, and also extend into gland, dividing it into lobes – Classified by: ▪ Structure ▪ Mode of secretion Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Glandular Epithelia Multicellular exocrine glands (cont.) – Structure ▪ Simple exocrine glands have unbranched ducts, but compound glands have branched ducts ▪ In a tubular gland, secretory cells form a duct, whereas in alveolar glands, secretory cells form sacs – Tubuloalveolar glands have both types Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Multicellular Exocrine Glands Simple duct structure Compound duct structure (duct does not branch) (duct branches) Tubular secretory structure Simple tubular Simple branched tubular Example Example Compound tubular Intestinal glands Stomach (gastric) Example glands Duodenal glands of small intestine Alveolar secretory structure Simple alveolar Simple branched alveolar Example Example Compound alveolar Compound tubuloalveolar No important example Sebaceous (oil) glands Example Example in humans Mammary glands Salivary glands Surface epithelium Duct Secretory epithelium Figure 4.7 Types of multicellular exocrine glands. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Glandular Epithelia Multicellular exocrine glands (cont.) – Mode of secretion ▪ Merocrine: most secrete products by exocytosis as secretions are produced (sweat, pancreas) ▪ Holocrine: accumulate products within, then rupture (sebaceous oil glands) ▪ Apocrine: accumulate products within, but only apex ruptures; whether this type exists in humans is controversial (maybe mammary cells?) Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Chief Modes of Secretion in Human Exocrine Glands Secretory cell fragments Secretory vesicles (a) Merocrine glands secrete their (b) In holocrine glands, the entire secretory products by exocytosis. cell ruptures, releasing secretions and dead cell fragments. Figure 4.8 Chief modes of secretion in human exocrine glands. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Human Anatomy and Physiology Eleventh Edition Chapter 04 Part B Tissue: The Living Fabric PowerPoint® Lectures Slides prepared by Karen Dunbar Kareiva, Ivy Tech Community College Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 4.3 Connective Tissue Connective tissue is the most abundant and widely distributed of primary tissues Major functions: binding and support, protecting, insulating, storing reserve fuel, and transporting substances (blood) Four main classes – Connective tissue proper – Cartilage – Bone – Blood Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Table 4.1-1 Comparison of Classes of Connective Tissues Table 4.1-1 Comparison of Classes of Connective Tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Table 4.1-2 Comparison of Classes of Connective Tissues Table 4.1-2 Comparison of Classes of Connective Tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Common Characteristics of Connective Tissue Three characteristics make connective tissues different from other primary tissues: – All have common embryonic origin: all arise from mesenchyme tissue as their tissue of origin – Have varying degrees of vascularity (cartilage is avascular, bone is highly vascularized) – Cells are suspended/embedded in extracellular matrix (ECM) (protein-sugar mesh, non-living) ▪ Matrix supports cells so they can bear weight, withstand tension, endure abuse Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Structural Elements of Connective Tissue All connective tissues have three main elements – Ground substance – Fibers – Cells ▪ The first two elements (ground substance and fibers) together make up the extracellular matrix – Composition and arrangement of these three elements vary considerably in different types of connective tissues Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Structural Elements of Connective Tissue Ground substance – Unstructured gel-like material that fills space between cells ▪ Medium through which solutes diffuse between blood capillaries and cells – Components ▪ Interstitial fluid ▪ Cell adhesion proteins (“glue” for attachment) ▪ Proteoglycans (sugar proteins), made up of protein core + large polysaccharides – Example: chrondroitin sulfate and hyaluronic acid ▪ Water also is trapped in varying amounts, affecting viscosity of ground substance Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Structural Elements of Connective Tissue Connective tissue fibers Three types of fibers provide support – Collagen ▪ Strongest and most abundant type ▪ Tough; provides high tensile strength – Elastic fibers ▪ Networks of long, thin, elastin fibers that allow for stretch and recoil – Reticular ▪ Short, fine, highly branched collagenous fibers (different chemistry and form from collagen fibers) ▪ Branching forms networks that offer more “give” Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Structural Elements of Connective Tissue Cells – “Blast” cells ▪ Immature form of cell that actively secretes ground substance and ECM fibers ▪ Fibroblasts found in connective tissue proper ▪ Chondroblasts found in cartilage ▪ Osteoblasts found in bone ▪ Hematopoietic stem cells in bone marrow – “Cyte” cells ▪ Mature, less active form of “blast” cell that now becomes part of and helps maintain health of matrix – Blood is an exception Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Structural Elements of Connective Tissue Other cell types in connective tissues – Fat cells ▪ Store nutrients – White blood cells ▪ Neutrophils, eosinophils, lymphocytes ▪ Tissue response to injury – Mast cells ▪ Initiate local inflammatory response against foreign microorganisms they detect – Macrophages ▪ Phagocytic cells that “eat” dead cells, microorganisms; function in immune system Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved  Areolar Connective Tissue: A Prototype (Model) Connective Tissue Connective tissue is composed of (1) fibers, (2) ground substance, and (3) cells. Extracellular matrix Fibers Ground substance Cells Capillary Collagen fiber Elastic fiber Fat cell Reticular fiber Mast cell Neutrophil (a type of white blood cell) Fibroblast Macrophage Lymphocyte (a type of white blood cell) Figure 4.9 Areolar connective tissue: A prototype (model) connective tissue. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Overview of Types of Connective Tissue Areolar Loose Adipose Reticular Connective tissue Regular proper Dense Irregular Elastic Connective Tissue Hyaline Cartilage Elastic Fibrocartilage Bone Blood Figure 4.10 Overview of types of connective tissue. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues Connective tissue proper – Consists of all connective tissues except bone, cartilage, and blood – Two subclasses ▪ CT proper: loose connective tissues – Areolar – Adipose – Reticular ▪ CT proper: dense connective tissues – Dense regular – Dense irregular – Elastic Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues CT proper: loose connective tissues – Areolar connective tissue ▪ Most widely distributed CT ▪ Supports and binds other tissues (fibers) ▪ Universal packing material between other tissues ▪ Contains fibroblasts that secrete loose arrangement of mostly collagen fibers ▪ Loose fibers allow for increased ground substance, which can act as water reservoir by holding more interstitial fluid ▪ Macrophages and fat cells are contained in spaces Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Proper-Loose-Areolar (a) Connective tissue Proper Loose Areolar Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells. Elastic fibers Ground Function: Wraps and cushions organs; its substance macrophages phagocytize bacteria; plays important role in inflammation; holds and Fibroblast conveys tissue fluid. nuclei Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds Collagen capillaries. fibers Epithelium Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (340X). Lamina propria Figure 4.11a Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues CT proper: loose connective tissues (cont.) – Adipose tissue ▪ White fat – Similar to areolar tissue but greater nutrient storage – Cells are called adipocytes – Scanty matrix – Richly vascularized – Functions in shock absorption, insulation, and energy storage ▪ Brown fat – Use lipid fuels to heat bloodstream rather than to produce ATP, as does white fat Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Proper-Loose-Adipose (b) Connective tissue Proper Loose Adipose Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet. Nucleus of adipose (fat) cell Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs. Location: Under skin in subcutaneous tissue; Fat droplet around kidneys and eyeballs; within abdomen; in breasts. Adipose tissue Photomicrograph: Adipose tissue from the subcutaneous Mammary layer under the skin (350×). glands Figure 4.11b Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues CT proper: loose connective tissues (cont.) – Reticular connective tissue ▪ Resembles areolar tissue, but fibers are thinner reticular fibers ▪ Fibroblast cells are called reticular cells – Secrete reticular fibers made up of thin collagen ▪ Reticular fibers form a mesh-like stroma that acts as a support for blood cells in lymph nodes, spleen, and bone marrow Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Proper-Loose-Reticular (c) Connective tissue Proper Loose Reticular Description: Loose network of reticular fibers in a gel-like ground substance; reticular cells lie on the fibers. White blood cell Function: Fibers form a soft internal skeleton (lymphocyte) (stroma) that supports other cell types including white blood cells, mast cells, and macrophages. Location: Lymphoid organs (lymph nodes, Reticular bone marrow, and spleen). fibers Spleen Photomicrograph: Dark-staining network of reticular connective tissue fibers forming the internal skeleton of the spleen (350×). Figure 4.11c Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues CT proper: dense connective tissues – Three varieties of dense connective tissue ▪ Dense regular ▪ Dense irregular ▪ Elastic Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues CT proper: dense connective tissues (cont.) – Dense regular connective tissue ▪ Very high tensile strength; can withstand high tension and stretching ▪ Closely packed bundles of thick collagen fibers run parallel to direction of pull – Fibers appear as white structures Great resistance to pulling – Fibers slightly wavy, so stretch a little ▪ Fibroblasts manufacture collagen fibers and ground substance ▪ Very few cells and ground substance, mostly fibers ▪ Poorly vascularized ▪ Example: tendons and ligaments Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Proper-Dense-Regular (d) Connective tissue Proper Dense Regular Description: Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast. Collagen fibers Function: Attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. Nuclei of fibroblasts Location: Tendons, most ligaments, aponeuroses. Shoulder joint Ligament Photomicrograph: Dense regular connective tissue from a Tendon tendon (430×). Figure 4.11d Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues CT proper: dense connective tissues (cont.) – Dense irregular connective tissue ▪ Same elements as dense regular, but bundles of collagen are thicker and irregularly arranged ▪ Forms sheets rather than bundles ▪ Resists tension from many directions ▪ Found in: – Dermis – Fibrous joint capsules – Fibrous coverings of some organs Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Proper-Dense-Irregular (e) Connective tissue Proper Dense Irregular Description: Primarily irregularly arranged collagen fibers; some elastic fibers; fibroblast is the major cell type. Nuclei of fibroblasts Function: Withstands tension exerted in many directions; provides structural strength. Location: Fibrous capsules of organs and of joints; dermis of the skin; submucosa of Collagen digestive tract. fibers Shoulder joint Fibrous joint capsule Photomicrograph: Dense irregular connective tissue from the fibrous capsule of a joint (430×). Figure 4.11e Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues CT proper: dense connective tissues (cont.) – Elastic connective tissue ▪ Some ligaments are very elastic – Example: ligaments connecting adjacent vertebrae must be very elastic ▪ Also found in walls of many large arteries – Arteries need to stretch when blood enters and recoil to push blood out Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Proper-Dense-Elastic (f) Connective tissue Proper Dense Elastic Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows tissue to recoil after stretching; maintains pulsatile flow of blood Elastic fibers through arteries; aids passive recoil of lungs following inspiration. Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. Aorta Photomicrograph: Elastic connective tissue in the wall of the aorta (250×). Heart Figure 4.11f Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Concept review 2 Which of the following cell types is most associated with the initiation of local inflammatory responses to foreign microorganisms? A) macrophages B) chondroblasts C) fibroblasts D) mast cells E) white blood cells Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues Cartilage – Matrix secreted from chondroblasts (during growth) and chondrocytes (adults) ▪ Chondrocytes found in cavities called lacunae ▪ 80% water, with packed collagen fibers and sugar proteins (chondroitin and hyaluronic acid) – Tough yet flexible material, withstands tension and compression – lacks nerve fibers – Avascular: receives nutrients from membrane surrounding it (perichondrium) ▪ Periochondrium gives rise to chondroblasts and chondrocytes Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues Three types of cartilage: – Hyaline cartilage ▪ Most abundant; “gristle” ▪ Appears as shiny bluish glass ▪ Found at tips of long bones, nose, trachea, larynx, and cartilage of the ribs – Elastic cartilage ▪ Similar to hyaline but with more elastic fibers ▪ Found in ears and epiglottis – Fibrocartilage ▪ Properties between hyaline and dense regular tissue ▪ Strong, so found in areas such as intervertebral discs and knee Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Cartilage-Hyaline (g) Connective tissue Cartilage Hyaline Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (as chondrocytes) lie in lacunae. Chondrocyte in lacuna Function: Supports and reinforces; serves as resilient cushion; resists compressive stress. Location: Forms most of the embryonic Matrix skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx. Costal cartilages Photomicrograph: Hyaline cartilage from a costal cartilage of a rib (470×). Figure 4.11g Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Cartilage-Elastic (h) Connective tissue Cartilage Elastic Description: Similar to hyaline cartilage, but more elastic fibers in matrix. Elastic fibers Chondrocyte in lacuna Function: Maintains the shape of a structure while allowing great flexibility. Matrix Location: Supports the external ear (pinna); epiglottis. Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (510×). Figure 4.11h Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Cartilage-Fibrocartilage (i) Connective tissue Cartilage Fibrocartilage Description: Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate. Function: Tensile strength allows it to absorb compressive shock. Chondrocytes Location: Intervertebral discs; pubic in lacunae symphysis; discs of knee joint. Intervertebral Collagen discs fiber Photomicrograph: Fibrocartilage of an intervertebral disc (125×). Special staining produced the blue color seen. Figure 4.11i Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Clinical – Homeostatic Imbalance 4.2 Avascular cartilage loses ability to divide as we age, so injuries heal slowly – Common in people with sports injuries Later in life, cartilage can calcify or ossify (become bony), causing chondrocytes to die Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues Bone – Also called osseous tissue – Supports and protects body structures – Stores fat and synthesizes blood cells in cavities – Has more collagen compared to cartilage – Has inorganic calcium salts – Osteoblasts produce matrix – Osteocytes maintain the matrix ▪ Reside in cavities in matrix called lacunae – Osteons: individual structural units – Richly vascularized Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Bone (j) Connective tissue Bone Description: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized. Central canal Lacunae Function: Supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for Lamella blood cell formation (hematopoiesis). Location: Bones. Photomicrograph: Cross-sectional view of bone (125×). Figure 4.11j Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Types of Connective Tissues Blood – Most atypical connective tissue because it is fluid ▪ Consists of cells surrounded by matrix (plasma) ▪ Originates from the mesenchyme – Red blood cells are most common cell type – Also contains white blood cells and platelets – Fibers are soluble proteins that precipitate during blood clotting – Functions in transport and in carrying nutrients, wastes, gases, and other substances Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Connective Tissues-Blood (k) Connective tissue Blood Description: Red and white blood cells in a fluid matrix (plasma). Red blood cells (erythrocytes) White blood cells: Lymphocyte Neutrophil Function: Transports respiratory gases, nutrients, wastes, and other substances. Location: Contained within blood vessels. Plasma Photomicrograph: Smear of human blood (1670×); shows two white blood cells surrounded by red blood cells. Figure 4.11k Connective tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 4.4 Muscle Tissue Highly vascularized Responsible for most types of movement – Muscle cells possess myofilaments made up of actin and myosin proteins that bring about contraction Three types of muscle tissues: – Skeletal muscle – Cardiac muscle – Smooth muscle Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Skeletal Muscle Skeletal muscle tissue – Attached to and causes movement of bones – Also called voluntary muscle ▪ Skeletal muscles can be consciously controlled – Cells are called muscle fibers ▪ Contain multiple nuclei ▪ Appear striated or banded Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Skeletal Muscle (a) Skeletal muscle Description: Long, cylindrical, multinucleate cells; obvious striations. Part of Function: Voluntary movement; locomotion; muscle manipulation of the environment; facial fiber (cell) expression; voluntary control. Nuclei Location: In skeletal muscles attached to bones or occasionally to skin. Striations Photomicrograph: Skeletal muscle (440×). Notice the obvious banding pattern and the fact that these large cells are multinucleate. Figure 4.12a Muscle tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Cardiac Muscle Cardiac muscle tissue – Found only in walls of heart – Involuntary muscle – Like skeletal muscle, contains striations; but cells have only one nucleus – Cells can have many branches that join branches of other cardiac cells ▪ Intercalated discs are special joints where cardiac cells are joined Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Cardiac Muscle (b) Cardiac muscle Description: Branching, striated, generally uninucleate cells that connect at specialized junctions (intercalated discs). Function: As it contracts, it propels blood Intercalated into the circulation; involuntary control. discs Striations Location: The walls of the heart. Nucleus Photomicrograph: Cardiac muscle (475×); notice the striations, branching of cells, and the intercalated discs. Figure 4.12b Muscle tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Smooth Muscle Smooth muscle tissue – Found mainly in walls of hollow organs (other than heart) – Involuntary muscle – Has no visible striations – Spindle-shaped cells with one nucleus Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Smooth Muscle (c) Smooth muscle Description: Cells are spindle shaped (tapered on both ends) with central nuclei; no striations; cells arranged closely to form sheets. Smooth muscle Function: Propels substances or objects cell (foodstuffs, urine, a baby) along internal passageways; involuntary control. Nuclei Location: Mostly in the walls of hollow organs. Photomicrograph: Sheet of smooth muscle from the digestive tract (465×). Figure 4.12c Muscle tissues. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 4.5 Nervous Tissue Main component of nervous system (brain, spinal cord, nerves) – Regulates and controls body functions Made up of two specialized cells: – Neurons: specialized nerve cells that generate and conduct nerve impulses – Glial or neuroglia - supporting cells that support, insulate, and protect neurons Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Nervous Tissue Nervous tissue Description: Neurons are branching cells; cell processes that may be quite long extend from the nucleus-containing cell body; also contributing to nervous Nuclei of tissue are nonexcitable supporting cells. supporting cells Neuron processes Cell body Axon Dendrites Cell body of a neuron Function: Neurons transmit electrical signals from sensory receptors and to effectors (muscles and glands); supporting cells support and protect neurons. Neuron processes Location: Brain, spinal cord, and nerves. Photomicrograph: Neurons (350×) Figure 4.13 Nervous tissue. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 4.6 Covering and Lining Membranes Composed of at least two primary tissue types: an epithelium bound to underlying connective tissue proper layer Three types – Cutaneous membranes – Mucous membranes – Serous membranes Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Cutaneous Membranes Another name for skin Keratinized stratified squamous epithelium (epidermis) attached to a thick layer of connective tissue (dermis) Unlike other membranes, skin is a dry membrane Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classes of Covering and Lining Membranes (a) Cutaneous membrane The cutaneous membrane (the skin) covers the body surface. Cutaneous membrane (skin) Figure 4.14a Classes of covering and lining membranes. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Mucous Membranes Mucosa indicates location, not cell composition Also called mucosae – Line body cavities that are open to the exterior (example: digestive, respiratory, urogenital tracts) Moist membranes bathed by secretions (or urine) Epithelial sheet lies over layer of loose (areolar) connective tissue called lamina propria May secrete mucus Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classes of Covering and Lining Membranes (b) Mucous membranes (mucosae) Mucous membranes line body cavities that are open to the exterior. Mucosa of nasal cavity Mucosa of mouth Esophagus lining Mucosa of lung bronchi Figure 4.14b Classes of covering and lining membranes. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Serous Membranes Also called serosae Found in closed ventral body cavities Constructed from simple squamous epithelium (called mesothelium) resting on thin areolar connective tissue Parietal serosae line internal body cavity walls Visceral serosae cover internal organs Cavity between layers is filled with slippery serous fluid, so these are moist membranes Special names given to show location: pleurae (lungs), pericardium (heart), peritoneum (abdomen) Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classes of Covering and Lining Membranes (c) Serous membranes Serous membranes line body cavities that are closed to the exterior. The pleurae surround the lungs. Parietal pleura Visceral pleura Parietal Visceral The pericardium pericardium pericardium surrounds the heart. The peritoneum surrounds the digestive organs. Parietal peritoneum Visceral peritoneum Figure 4.14c Classes of covering and lining membranes. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 4.7 Tissue Repair When the body’s barriers are compromised, the inflammatory and immune responses are activated Repair starts very quickly Repair is the function of the inflammatory process Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Steps in Tissue Repair Repair can occur in two major ways: – Regeneration: same kind of tissue replaces destroyed tissue, so original function is restored – Fibrosis: connective tissue replaces destroyed tissue with scar tissue (dense connective tissue) and original function lost Step 1: Inflammation sets stage – Release of inflammatory chemicals causes: ▪ Dilation of blood vessels ▪ Increase in blood vessel permeability – Clotting of blood occurs Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Tissue Repair of a Nonextensive Skin Wound: Regeneration and Fibrosis Scab Blood clot in cut skin 1 Inflammation sets the stage: Epidermis Trauma causes injured tissue cells, mast cells, and others to release inflammatory chemicals. Vein Inflammatory chemicals make local blood vessels leaky, allowing white blood cells, fluid, clotting proteins, and other plasma proteins to seep into the injured area. Clotting seals off the injured area Inflammatory Migrating Artery and prevents bacteria, toxins, and chemicals white blood cell other harmful substances from spreading. The surface of the clot exposed to air dries and forms a scab. Figure 4.15 Tissue repair of a nonextensive skin wound: regeneration and fibrosis. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Steps in Tissue Repair Step 2: Organization restores blood supply – Organization begins as the blood clot is replaced with granulation tissue (new capillary-enriched tissue) – Epithelium begins to regenerate – Fibroblasts produce collagen fibers to bridge the gap until regeneration is complete – Any debris in area is phagocytized Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Tissue Repair of a Nonextensive Skin Wound: Regeneration and Fibrosis Regenerating epithelium 2 Organization restores the blood supply: Area of The clot is replaced by the ingrowth of granulation fragile capillaries that are characteristic tissue ingrowth of granulation tissue. This restores the Fibroblast vascular supply. Macrophage Fibroblasts multiply and produce Budding growth factors and collagen fibers that capillary bridge the gap. When healing is complete, these fibroblasts revert to the resting stage or undergo apoptosis (cell suicide). Macrophages phagocytize dead and dying cells and other debris. Surface epithelial cells multiply and begin to migrate over the granulation tissue. Figure 4.15 Tissue repair of a nonextensive skin wound: regeneration and fibrosis. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Steps in Tissue Repair Step 3: Regeneration and fibrosis effect permanent repair – The scab detaches – Fibrous tissue matures – Epithelium thickens and begins to resemble adjacent tissue – Results in a fully regenerated epithelium with underlying scar tissue, which may or may not be visible Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Tissue Repair of a Nonextensive Skin Wound: Regeneration and Fibrosis Regenerated epithelium 3 Regeneration and fibrosis effect permanent repair: The fibrosed area matures and contracts, pulling the margins of the wound together. Fibrosed area As it regenerates, the epithelium thickens under the scab, which detaches. A fully regenerated epithelium with an underlying area of scar tissue results. The scar may be visible as a white line, depending on the severity of the wound. Figure 4.15 Tissue repair of a nonextensive skin wound: regeneration and fibrosis. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Regenerative Capacity of Different Tissues Tissues that regenerate extremely well include: – Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, blood-forming tissue Tissue with moderate regenerating capacity: – Smooth muscle and dense regular connective tissue Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Regenerative Capacity of Different Tissues Tissues with virtually no functional regenerative capacity: – Cardiac muscle and nervous tissue of brain and spinal cord – New research shows cell division does occur, and efforts are underway to coax them to regenerate better Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Clinical – Homeostatic Imbalance 4.3 Scar tissue that forms in organs, particularly the heart, can severely impair the function of that organ – May cause the organ to lose volume capacity – May block substances from moving through organ – May interfere with ability of muscles to contract or may impair nerve transmissions Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Midterm 1 Monday Sept. 30th, in-person, from 4:10pm-6:10pm (2 hours), ENG 103 Will only cover material from: – Lec 1 Chemistry comes alive – Lec 2 Cell: the living units – Lec 3 Tissues: the living fabric Will be entirely multiple choice and true/false Questions will be generated from slide material only, not sections of the textbook which were never discussed in-class. Bring student ID, pen and pencil No aids allowed Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved