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PowerPoint® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community College CHAPTER 4 Tissue: The Living Fabric: Part A © Annie Leibovitz/Contact Press Images © 2013 Pearson Education, Inc. Tissue: The Living Fabric • Individual body cells 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 © 2013 Pearson Education, Inc. Types of Primary Tissues • Epithelial tissue – Covers • Connective tissue – Supports • Muscle tissue – Produces movement • Nerve tissue – Controls © 2013 Pearson Education, Inc. Figure 4.1 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 • Skin surface (epidermis) Connective tissue: Supports, protects, binds other tissues together • Bones • Tendons • Fat and other soft padding tissue © 2013 Pearson Education, Inc. Studying Human Tissue: Microscopy • Tissue is fixed – Preserved • Cut – Sliced thin enough to transmit light or electrons • Stained – Enhances contrast © 2013 Pearson Education, Inc. Epithelial Tissue (Epithelium) • Form boundaries • Two main types (by location) – Covering and lining epithelia • On external and internal surfaces – Glandular epithelia • Secretory tissue in glands © 2013 Pearson Education, Inc. Epithelial Tissue Functions • • • • • • Protection Absorption Filtration Excretion Secretion Sensory reception © 2013 Pearson Education, Inc. Five Characteristics of Epithelial Tissues • • • • • Polarity Specialized contacts Supported by connective tissues Avascular, but innervated Can regenerate © 2013 Pearson Education, Inc. Characteristics of Epithelial Tissue: Polarity • Cells have polarity – Apical surface (upper free) exposed to exterior or cavity – Basal surface (lower, attached) – Both surfaces differ in structure and function © 2013 Pearson Education, Inc. Figure 4.2a Classification of epithelia. Apical surface Basal surface Simple Apical surface Basal surface Stratified Classification based on number of cell layers. © 2013 Pearson Education, Inc. Apical Surface of Epithelial Tissues • May be smooth & slick • Most have microvilli (e.g., brush border of intestinal lining) – Increase surface area • Some have cilia (e.g., lining of trachea) © 2013 Pearson Education, Inc. Basal Surface of Epithelial Tissues • Noncellular basal lamina – Glycoprotein and collagen fibers lies adjacent to basal surface – Adhesive sheet – Selective filter – Scaffolding for cell migration in wound repair © 2013 Pearson Education, Inc. Characteristics of Epithelial Tissue: Specialized Contacts • Covering and lining epithelial tissues fit closely together – Form continuous sheets • Specialized contacts bind adjacent cells – Lateral contacts • Tight junctions • Desmosomes © 2013 Pearson Education, Inc. Characteristics of Epithelial Tissue: Connective Tissue Support • All are supported by connective tissue • Reticular lamina – Deep to basal lamina – Network of collagen fibers • Basement membrane – Basal lamina + reticular lamina – Reinforces epithelial sheet – Resists stretching and tearing – Defines epithelial boundary © 2013 Pearson Education, Inc. Characteristics of Epithelial Tissue: Avascular but Innervated • No blood vessels in epithelial tissue – Must be nourished by diffusion from underlying connective tissues • Is supplied by nerve fibers © 2013 Pearson Education, Inc. Characteristics of Epithelial Tissue: Regeneration • High regenerative capacity • Stimulated by loss of apical-basal polarity and lateral contacts – Some exposed to friction – Some exposed to hostile substances • If adequate nutrients can replace lost cells by cell division © 2013 Pearson Education, Inc. Classification of Epithelia • All epithelial tissues have two names – One indicates number of cell layers • Simple epithelia = single layer of cells • Stratified epithelia = two or more layers of cells – Shape can change in different layers – One indicates shape of cells • Squamous • Cuboidal • Columnar • In stratified epithelia, epithelia classified by cell shape in apical layer © 2013 Pearson Education, Inc. Figure 4.2a Classification of epithelia. Apical surface Basal surface Simple Apical surface Basal surface Stratified Classification based on number of cell layers. © 2013 Pearson Education, Inc. Cells of Epithelial Tissues • Squamous cells – Flattened and scalelike – Nucleus flattened • Cuboidal cells – Boxlike – Nucleus round • Columnar cells – Tall; column shaped – Nucleus elongated © 2013 Pearson Education, Inc. Figure 4.2b Classification of epithelia. Squamous Cuboidal Columnar Classification based on cell shape. © 2013 Pearson Education, Inc. Classification of Epithelia: Simple Epithelia • • • • Absorption Secretion Filtration Very thin © 2013 Pearson Education, Inc. Simple Squamous Epithelium • Cells flattened laterally • Cytoplasm sparse • Function where rapid diffusion is priority – i.e., kidney, lungs • Note description, function, location on next slide © 2013 Pearson Education, Inc. Figure 4.3a Epithelial tissues. Simple squamous epithelium 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 epithelial cells Function: Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae. Location: Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae). Photomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (140x). © 2013 Pearson Education, Inc. Simple Squamous Epithelium • Two other locations – Endothelium • The lining of lymphatic vessels, blood vessels, and heart – Mesothelium • The epithelium of serous membranes in the ventral body cavity © 2013 Pearson Education, Inc. Simple Cuboidal Epithelia • • • • Single layer of cells Secretion Absorption Forms walls of smallest ducts of glands and many kidney tubules • Note description, function, location on next slide © 2013 Pearson Education, Inc. Figure 4.3b Epithelial tissues. Simple cuboidal epithelium Description: Single layer of cubelike cells with large, spherical central nuclei. Simple cuboidal epithelial cells Nucleus Function: Secretion and absorption. Basement membrane Location: Kidney tubules; ducts and secretory portions of small glands; ovary surface. Connective tissue Photomicrograph: Simple cuboidal epithelium in kidney tubules (430x). © 2013 Pearson Education, Inc. Simple Columnar Epithelium • • • • Single layer of tall, closely packed cells Absorption Secretion Note description, function, location on next slide © 2013 Pearson Education, Inc. Figure 4.3c Epithelial tissues. Simple columnar epithelium Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells). Microvilli Simple columnar epithelial cell Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action. Location: Nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus. © 2013 Pearson Education, Inc. Mucus of goblet cell Basement membrane Photomicrograph: Simple columnar epithelium of the small intestine mucosa (660x). Pseudostratified Columnar Epitheliem • Cells vary in height – Cell nuclei at different levels – Appears stratified, but is not – Secretion – Absorption – Note description, function, location on next slide © 2013 Pearson Education, Inc. Figure 4.3d Epithelial tissues. Pseudostratified columnar epithelium Description: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia. Cilia Pseudostratified epithelial layer Function: Secrete substances, particularly mucus; propulsion of mucus by ciliary action. Location: Nonciliated type in male’s sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract. Trachea © 2013 Pearson Education, Inc. Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (800x). Basement membrane Stratified Epithelial Tissues • Two or more cell layers • Regenerate from below – Basal cells divide, cells migrate to surface • More durable than simple epithelia • Protection is major role © 2013 Pearson Education, Inc. Stratified Squamous Epithelium • Most widespread of stratified epithelia • Free surface squamous; deeper layers cuboidal or columnar • Located for wear and tear • Those farthest from basal layer (and therefore nutrients) less viable • Note description, function, location on next slide © 2013 Pearson Education, Inc. Figure 4.3e Epithelial tissues. Stratified squamous epithelium Description: Thick membrane 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 moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane. © 2013 Pearson Education, Inc. Nuclei Basement membrane Connective tissue Photomicrograph: Stratified squamous epithelium lining the esophagus (285x). Stratified Cuboidal Epithelium • Quite rare • Found in some sweat and mammary glands • Typically two cell layers thick © 2013 Pearson Education, Inc. Stratified Columnar Epithelium • Limited distribution in body • Small amounts in pharynx, male urethra, and lining some glandular ducts • Also occurs at transition areas between two other types of epithelia • Only apical layer columnar © 2013 Pearson Education, Inc. Transitional Epithelium • • • • • Forms lining of hollow urinary organs Basal layer cells are cuboidal or columnar Ability to change shape with stretch Apical cells vary in appearance Note description, function, location on next slide © 2013 Pearson Education, Inc. Figure 4.3f Epithelial tissues. Transitional epithelium 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. Photomicrograph: Transitional epithelium lining the bladder, relaxed state (360x); note the bulbous, or rounded, appearance of the cells at the surface; these cells flatten and elongate when the bladder fills with urine. © 2013 Pearson Education, Inc. Basement membrane Connective tissue Glandular Epithelia • Gland – One or more cells that makes and secretes an aqueous fluid called a secretion • Classified by – Site of product release—endocrine or exocrine – Relative number of cells forming the gland • unicellular (e.g., goblet cells) or multicellular © 2013 Pearson Education, Inc. Endocrine Glands • Ductless glands – Secretions not released into a duct • Secrete (by exocytosis) hormones that travel through lymph or blood to their specific target organs • Target organs respond in some characteristic way © 2013 Pearson Education, Inc. Exocrine Glands • Secretions released onto body surfaces (skin) or into body cavities • More numerous than endocrine glands • Secrete products into ducts • Examples include mucous, sweat, oil, and salivary glands © 2013 Pearson Education, Inc. Connective Tissue • Most abundant and widely distributed of primary tissues • Four main classes – Connective tissue proper – Cartilage – Bone – Blood © 2013 Pearson Education, Inc. Table 4.1 Comparison of Classes of Connective Tissues (1 of 2) © 2013 Pearson Education, Inc. Table 4.1 Comparison of Classes of Connective Tissues (2 of 2) © 2013 Pearson Education, Inc. Major Functions of Connective Tissue • • • • • Binding and support Protecting Insulating Storing reserve fuel Transporting substances (blood) © 2013 Pearson Education, Inc. Characteristics of Connective Tissue • Three characteristics make connective tissues different from other primary tissues – Have mesenchyme (an embryonic tissue) as their common tissue of origin – Have varying degrees of vascularity (blood vessels) – Have extracellular matrix • Connective tissue not composed mainly of cells • Largely nonliving extracellular matrix separates cells – So can bear weight, withstand tension, endure abuse © 2013 Pearson Education, Inc. Structural Elements of Connective Tissue • Three elements – Ground substance – Fibers – Cells • Composition and arrangement varies in different connective tissues © 2013 Pearson Education, Inc. Ground Substance • Unstructured 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 • Protein core + large polysaccharides (chrondroitin sulfate and hyaluronic acid) • Trap water in varying amounts, affecting viscosity of ground substance © 2013 Pearson Education, Inc. 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 than collagen fibers) • Branch, forming networks that offer more "give" © 2013 Pearson Education, Inc. Cells • "Blasts" cells – Immature forum; mitotically active; secrete ground substance and fibers – Fibroblasts in connective tissue proper – Chondroblasts in cartilage – Osteoblasts in bone – Hematopoietic stem cells in bone marrow – "Cyte" cells – Mature form; maintain matrix – Chondrocytes in cartilage – Osteocytes in bone © 2013 Pearson Education, Inc. 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 © 2013 Pearson Education, Inc. Figure 4.7 Areolar connective tissue: A prototype (model) connective tissue. Cell types Macrophage Fibroblast Lymphocyte Fat cell Mast cell Neutrophil Capillary © 2013 Pearson Education, Inc. Extracellular matrix Ground substance Fibers • Collagen fiber • Elastic fiber • Reticular fiber Types of Connective Tissues: Connective Tissue Proper • All connective tissues except bone, cartilage and blood • Two subclasses – Loose connective tissues • Areolar • Adipose • Reticular – Dense connective tissues (also called fibrous connective tissues) • Dense regular • Dense irregular • Elastic © 2013 Pearson Education, Inc. Areolar Connective Tissue • Support and bind other tissues – Universal packing material between other tissues • • • • • • • • Most widely distributed Provide reservoir of water and salts Defend against infection Store nutrients as fat Fibroblasts Loose arrangement of fibers Ground substance When inflamed soaks up fluid edema © 2013 Pearson Education, Inc. Figure 4.8a Connective tissues. Connective tissue proper: loose connective tissue, areolar Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells. Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid. Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries. Elastic fibers Ground substance Fibroblast nuclei Collagen fibers Epithelium Lamina propria © 2013 Pearson Education, Inc. Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (340x). Adipose Tissue • White fat – Similar to areolar but greater nutrient storage – Cell is adipocyte • Stores nutrients – Scanty matrix – Richly vascularized – Shock absorption, insulation, energy storage • Brown fat – Use lipid fuels to heat bloodstream not to produce atp © 2013 Pearson Education, Inc. Figure 4.8b Connective tissues. Connective tissue proper: loose connective tissue, 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. Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs. Nucleus of adipose (fat) cell Location: Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts. Adipose tissue Fat droplet Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (350x). Mammary glands © 2013 Pearson Education, Inc. Dense Regular Connective Tissue • Closely packed bundles of collagen fibers running parallel to direction of pull – White structures with great resistance to pulling – Fibers slightly wavy so stretch a little • Tendons/ligaments • Few cells • Poorly vascularized © 2013 Pearson Education, Inc. Figure 4.8d Connective tissues. Connective tissue proper: dense connective tissue, dense regular Description: Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast. Function: Attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. Collagen fibers Location: Tendons, most ligaments, aponeuroses. Nuclei of fibroblasts Shoulder joint Ligament Tendon © 2013 Pearson Education, Inc. Photomicrograph: Dense regular connective tissue from a tendon (430x). Dense Irregular Connective Tissue • Same elements but bundles of collagen thicker and irregularly arranged • Found in Joints and fibrous organs • Resists tension from many directions – Dermis – Fibrous joint capsules – Fibrous coverings of some organs © 2013 Pearson Education, Inc. Figure 4.8e Connective tissues. Connective tissue proper: dense connective tissue, 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 digestive tract. Collagen fibers Shoulder joint Fibrous joint capsule Photomicrograph: Dense irregular connective tissue from the fibrous capsule of a joint (430x). © 2013 Pearson Education, Inc. Elastic Connective Tissue • Some ligaments very elastic – Those connecting adjacent vertebrae • Many of larger arteries have in walls © 2013 Pearson Education, Inc. Figure 4.8f Connective tissues. Connective tissue proper: dense connective tissue, 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 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. Elastic fibers Aorta Heart © 2013 Pearson Education, Inc. Photomicrograph: Elastic connective tissue in the wall of the aorta (250x). Cartilage • • • • Chondroblasts and chondrocytes Tough yet flexible Lacks nerve fibers Up to 80% water - can rebound after compression • Avascular – Receives nutrients from membrane surrounding it • Perichondrium • Three types of cartilage: – Hyaline cartilage – Elastic cartilage – Fibrocartilage © 2013 Pearson Education, Inc. Figure 4.8g Connective tissues. Cartilage: hyaline Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; serves as resilient cushion; resists compressive stress. Chondrocyte in lacuna Location: Forms most of the embryonic 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 © 2013 Pearson Education, Inc. Matrix Photomicrograph: Hyaline cartilage from a costal cartilage of a rib (470x). Figure 4.8h Connective tissues. Cartilage: elastic Description: Similar to hyaline cartilage, but more elastic fibers in matrix. Function: Maintains the shape of a structure while allowing great flexibility. Chondrocyte in lacuna Matrix Location: Supports the external ear (pinna); epiglottis. Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (800x). © 2013 Pearson Education, Inc. Figure 4.8i Connective tissues. 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. Location: Intervertebral discs; pubic symphysis; discs of knee joint. Chondrocytes in lacunae Intervertebral discs Collagen fiber Photomicrograph: Fibrocartilage of an intervertebral disc (125x). Special staining produced the blue color seen. © 2013 Pearson Education, Inc. Bone • • • • • • • • • Also called osseous tissue Supports and protects body structures Stores fat and synthesizes blood cells in cavities More collagen than cartilage Has inorganic calcium salts Osteoblasts produce matrix Osteocytes maintain the matrix Osteons – structural units Richly vascularized © 2013 Pearson Education, Inc. Figure 4.8j Connective tissues. Others: bone (osseous tissue) Description: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized. 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 blood cell formation (hematopoiesis). Central canal Lacunae Lamella Location: Bones Photomicrograph: Cross-sectional view of bone (125x). © 2013 Pearson Education, Inc. Blood • Most atypical connective tissue – is a fluid • Red blood cells most common cell type • Also contains white blood cells and platelets • Fibers are soluble proteins that precipitate during blood clotting • Functions in transport © 2013 Pearson Education, Inc. Figure 4.8k Connective tissues. Connective tissue: blood Description: Red and white blood cells in a fluid matrix (plasma). Red blood cells (erythrocytes) Function: Transport respiratory gases, nutrients, wastes, and other substances. White blood cells: • Lymphocyte • Neutrophil Location: Contained within blood vessels. Plasma Photomicrograph: Smear of human blood (1670x); shows two white blood cells surrounded by red blood cells. © 2013 Pearson Education, Inc.