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4 Tissue Level of Organization PowerPoint® Lecture Presentations prepared by Alexander G. Cheroske Mesa Community College at Red Mountain © 2011 Pearson Education, Inc. Section 1: Epithelial Tissue • Learning Outcomes • 4.1 Describe epithelial tissues, including cell shape, layers, and functions. • 4.2 Discuss the types and functions of intercellular connections between epithelial cells. • 4.3 Describe the structure and function of squamous epithelium. • 4.4 Describe the structure, function, and locations of cuboidal and transitional epithelia. © 2011 Pearson Education, Inc. Section 1: Epithelial Tissue • Learning Outcomes • 4.5 Describe the structure, function, and locations of columnar epithelia. • 4.6 Describe the structure, function, and locations of glandular epithelia. © 2011 Pearson Education, Inc. Section 1: Epithelial Tissue • Atoms Molecules Cells Tissues • Chemical level imaged only with special techniques • Cellular level imaged often with electron microscope • Body contains trillions of cells • Only ~200 types of cells • Tissue level can be imaged with light microscope © 2011 Pearson Education, Inc. Section 1: Epithelial Tissue • Tissues (cells working together) • Histology (study of tissues) • Four basic types 1. Epithelial 2. Connective 3. Muscle 4. Neural © 2011 Pearson Education, Inc. The tissue level of organization, which consists of four tissue types The Chemical Level MOLECULES combine to form ATOMS interact to form The Cellular Level that secrete and regulate CELLS EXTRACELLULAR MATERIAL AND FLUIDS combine to form The Tissue Level TISSUES with special functions can be classified as EPITHELIAL TISSUE • Covers exposed surfaces • Lines internal passageways and chambers • Produces glandular secretions CONNECTIVE TISSUE • Fills internal spaces • Provides structural support MUSCLE TISSUE • Contracts to produce active movement NEURAL TISSUE • Conducts electrical impulses • Carries information • Stores energy Figure 4 Section 1 © 2011 Pearson Education, Inc. Module 4.1: Epithelial tissue • Epithelial tissue • Epithelia • Cover exposed surfaces and internal cavities/passageways • Often contain secretory or gland cells • Scattered among other cell types • Glands (derived from epithelia but more secretory cells) • Two types 1. Exocrine glands • 2. Secrete on external areas Endocrine glands • © 2011 Pearson Education, Inc. Secrete hormones into interstitial fluid The components of epithelial tissue Epithelial Tissue Includes Epithelia Glands Epithelia cover exposed surfaces and line internal cavities and passageways; they often contain secretory cells, or gland cells, scattered among the other cell types. Glands are derived from epithelia, but secretory cells predominate; there are two types: Exocrine Glands Endocrine Glands Exocrine glands secrete onto external surfaces or into internal passageways (ducts) that connect to the exterior. Endocrine glands secrete hormones or precursors into the interstitial fluid, usually for distribution by the bloodstream. Figure 4.1 © 2011 Pearson Education, Inc. 1 Module 4.1: Epithelial tissue • Functions of epithelial tissue • Provide physical protection • Control permeability • Provide sensation • Produce specialized secretions © 2011 Pearson Education, Inc. Module 4.1: Epithelial tissue • Basic features of epithelial cells • Apical surface (faces exterior or internal space) • Microvilli often found on cells of digestive, urinary, and reproductive tracts • Cilia often found on cells lining respiratory and some parts of reproductive tracts • Faces lumen (space) when lining hollow organs • Base (attached to adjacent tissues) • Basolateral surfaces • Includes base and lateral surfaces (attached to neighboring cells) • Have membranous organelles comparable to other cell types © 2011 Pearson Education, Inc. Module 4.1: Epithelial tissue • Three epithelial cell shapes (perpendicular section) 1. Squamous (thin and flat) 2. Cuboidal (small boxes) 3. Columnar (slender rectangles) • Can be layered • Single layer (simple epithelium) • Several layers (stratified epithelium) • Generally located in areas that need protection © 2011 Pearson Education, Inc. Module 4.1 Review a. List four essential functions of epithelial tissue. b. Summarize the classification of an epithelium based on cell shape and number of cell layers. c. What is the probable function of an epithelial surface whose cells bear many cilia? © 2011 Pearson Education, Inc. Module 4.2: Epithelial cells are extensively interconnected • Many types of connections to form complete cover or lining • Have ability to replace damaged or lost cells • Lack blood vessels (avascular) • Lowest cell layers must remain attached to underlying tissues to be near blood vessels Animation: Intercellular Connections © 2011 Pearson Education, Inc. Microvilli The structures that connect epithelial cells to each other and to adjacent tissues APICAL SURFACE Intercellular attachments Occluding junctions form a barrier that isolates the basolateral surfaces and deeper tissues from the contents of the lumen. An adhesion belt locks together the terminal webs of neighboring cells, strengthening the apical region and preventing distortion and leakage at the occluding junctions. Gap junctions permit chemical communication that coordinates the activities of adjacent cells. Desmosomes (DEZ-mō-sōms; desmos, ligament + soma, body) provide firm attachment between neighboring cells by interlocking their cytoskeletons. BASE Basal Lamina Hemidesmosome © 2011 Pearson Education, Inc. Figure 4.2 1 Module 4.2: Epithelial cells are extensively interconnected • Hemidesmosomes • Made of peripheral and transmembrane proteins • Attach deepest epithelial cells to basal lamina • Basal lamina (basement membrane) layers 1. Clear layer (lamina lucida) • Contains glycoproteins and fine protein filaments 2. Dense layer (lamina densa) • Contains bundles of coarse protein fibers • Gives strength and restricts diffusion © 2011 Pearson Education, Inc. The structures that connect epithelial cells to each other and to adjacent tissues Basal Lamina Intermediate filaments of the cytoskeleton Hemidesmosome The basal lamina, or basement membrane, is a complex structure produced by the basal surface of the epithelium and the underlying connective tissue. The clear layer, or lamina lucida (LAM-i-nah LOO-si-dah; lamina, thin layer + lucida, clear) contains glycoproteins and a network of fine protein filaments. A hemidesmosome, which attaches the deepest epithelial cells to the basal lamina The dense layer, or lamina densa, containing bundles of coarse protein fibers, gives the basal lamina its strength and acts as a filter that restricts diffusion between the adjacent tissues and the epithelium. Figure 4.2 © 2011 Pearson Education, Inc. 2 Module 4.2: Epithelial cells are extensively interconnected • Types of intercellular attachments • Occluding junctions • Form barrier that prevents lumen contents from getting past cells • Adjacent plasma membranes tightly bound with proteins • Adhesion belt • Attaches terminal webs of adjacent cells • Reinforces occluding junctions • Dense protein band surrounding cell © 2011 Pearson Education, Inc. The structures that connect epithelial cells to each other and to adjacent tissues At an occluding junction, the lipid portions of the two plasma membranes are tightly bound together by interlocking membrane proteins. An occluding junction Figure 4.2 © 2011 Pearson Education, Inc. 3 The structures that connect epithelial cells to each other and to adjacent tissues An adhesion belt Figure 4.2 © 2011 Pearson Education, Inc. 4 Module 4.2: Epithelial cells are extensively interconnected • Types of intercellular attachments (continued) • Gap junctions • Permit chemical communication to coordinate activities of adjacent cells • Formed by interlocking junctional proteins (connexons) • Examples: ciliated epithelial tissues, cardiac muscle tissue • Desmosomes (desmos, ligament + soma, body) • Interlock cytoskeletons of adjacent cells • Very strong • Formed by: • Cell adhesion molecules (CAMs) • Intercellular cement (thin layer of proteoglycans, notably hyaluronan) © 2011 Pearson Education, Inc. The structures that connect epithelial cells to each other and to adjacent tissues Connexons are channel proteins that form a narrow passageway and let small molecules and ions pass from cell to cell. An jap junction Figure 4.2 © 2011 Pearson Education, Inc. 5 The structures that connect epithelial cells to each other and to adjacent tissues Cell adhesion molecules (CAMs) are transmembrane proteins that bind to each other and to extracellular materials. A desmosome The membranes of adjacent cells may also be bonded by intercellular cement, a thin layer of proteoglycans that contain polysaccharide derivatives, most notably hyaluronan. Figure 4.2 © 2011 Pearson Education, Inc. 6 Module 4.2 Review a. Identify the various types of epithelial intercellular connections. b. How do epithelial tissues, which are avascular, obtain needed nutrients? c. What is the functional significance of gap junctions? © 2011 Pearson Education, Inc. Module 4.3: Squamous epithelia • Simple squamous epithelium (squama, plate or scale) • Thin and flat, irregular in shape • Surface view: like fried eggs side to side • Sectional view: jigsaw pieces with disc-shaped nucleus • Found in protected regions • Where absorption or diffusion takes place • Examples: along kidney passages, inside eye, alveoli of the lung • Where a slippery surface reduces friction • Lining ventral body cavity (mesothelium) • Lining heart and blood vessels (endothelium) © 2011 Pearson Education, Inc. Simple squamous epithelia, which include the specially named endothelium and mesothelium Endothelium lining the inside of the heart and blood vessels Mesothelium lining the pericardial cavity and the peritoneal cavity Connective tissue Nucleus Cytoplasm Sectioned epithelial cell The surface of a simple squamous epithelium Section of peritoneum Simple squamous epithelium LM x 270 Figure 4.3 © 2011 Pearson Education, Inc. 1 Module 4.3: Squamous epithelia • Stratified squamous epithelium • Located where mechanical or chemical stresses are severe • Series of layers • Example locations: skin, mouth, throat, esophagus, rectum, anus, vagina © 2011 Pearson Education, Inc. A stratified squamous epithelium Squamous superficial cells Stem cells Basal lamina Connective tissue Surface of the tongue LM x 400 Figure 4.3 © 2011 Pearson Education, Inc. 2 Module 4.3: Squamous epithelia • Stratified squamous epithelium • Two types 1. Keratinized (with keratin proteins) • Tough and water resistant • Found at surface of skin 2. Nonkeratinized • Resists abrasion but can dry out • Found in oral cavity, pharynx, esophagus, anus, vagina © 2011 Pearson Education, Inc. The structure of a keratinized stratified squamous epithelium Keratinized skin cells Keratin fibers Surface of human skin Figure 4.3 © 2011 Pearson Education, Inc. 3 Module 4.3 Review a. What properties are common to keratinized epithelia? b. Why do the pharynx, esophagus, anus, and vagina have a similar epithelial organization? c. Under a light microscope, simple squamous epithelium is seen on the outer surface. Could this be a skin surface sample? Why or why not? © 2011 Pearson Education, Inc. Module 4.4: Cuboidal and transitional epithelia • Cuboidal epithelium • Cells resemble hexagonal boxes with nucleus in center • Types 1. Simple cuboidal epithelium • Locations • Lining exocrine glands and ducts • Portions of kidney • Secretory chambers of thyroid gland 2. Stratified cuboidal epithelium • Rare • Locations • © 2011 Pearson Education, Inc. Ducts of various exocrine glands Examples of cuboidal epithelia Connective tissue Basal lamina Simple cuboidal cells Lumen of duct Nucleus A cuboidal epithelium LM x 1400 The simple cuboidal epithelium in a sectioned kidney tubule Lumen of duct Stratified cuboidal cells Basal lamina Nuclei Connective tissue The stratified cuboidal epithelium in a sweat gland duct © 2011 Pearson Education, Inc. LM x 1413 Figure 4.4 1 – 3 Module 4.3: Squamous epithelia • Transitional epithelium • Unusual stratified epithelium that stretches and recoils • Transitional = changes • Locations • Urinary bladder • Urethra • Urine-collecting chambers of kidneys © 2011 Pearson Education, Inc. The transitional epithelium in an empty and a full urinary bladder Epithelium in a Relaxed Bladder In an empty urinary bladder, the superficial cells are typically plump and cuboidal. Epithelium (relaxed) Basal lamina Relaxed bladder Connective tissue and smooth muscle layers LM x 400 Figure 4.4 © 2011 Pearson Education, Inc. 4 Module 4.4 Review a. Identify the epithelium that lines the urinary bladder and changes in appearance as stretching occurs. b. Describe the appearance of simple cuboidal epithelial cells in sectional view. c. Stratified cuboidal epithelia are associated with what epithelial structures? © 2011 Pearson Education, Inc. Module 4.5: Columnar epithelia • Columnar epithelium • Cells appear rectangular in sectional view • Elongated nuclei near basal lamina • Types 1. Simple columnar epithelium • Locations • Stomach • Intestine • Uterine tubes • Kidney ducts © 2011 Pearson Education, Inc. The simpler columnar epithelium in the intestinal lining Microvilli Cytoplasm Nucleus Basal lamina Loose connective tissue LM x 350 Figure 4.5 © 2011 Pearson Education, Inc. 1 Module 4.5: Columnar epithelia • Columnar epithelium • Types (continued) 2. Pseudostratified columnar epithelium • Varying cell shapes and functions • Nuclei located at different areas of cell, so appears stratified • Every cell attached to basal lamina • Cells typically possess cilia • Locations • Nasal cavities • Trachea • Larger airways of lungs © 2011 Pearson Education, Inc. The pseudostratified columnar epithelium in the trachea Cilia Cytoplasm Nuclei Basal lamina Loose connective tissue LM x 394 Figure 4.5 © 2011 Pearson Education, Inc. 2 Module 4.5: Columnar epithelia • Columnar epithelium • Types (continued) 3. Stratified columnar epithelium • Relatively rare • Either two or multiple layers • • In multiple layers, only superficial cells are columns Located in large ducts of salivary glands and pancreas © 2011 Pearson Education, Inc. The stratified columnar epithelium in a salivary gland duct Loose connective tissue Basal cells Lumen Superficial columnar cells Lumen Cytoplasm Nuclei Basal lamina LM x 175 Figure 4.5 © 2011 Pearson Education, Inc. 3 Module 4.5 Review a. Describe the appearance of simple columnar epithelial cells in a sectional view. b. Explain why a pseudostratified columnar epithelium is not truly stratified. c. The columnar epithelium lining the intestine typically has ___________ on its apical surface. © 2011 Pearson Education, Inc. Module 4.6: Glandular epithelia • Glands • Collections of epithelial cells that produce secretions • Can be scattered cells or complex organs • Two types of glandular organs 1. Endocrine glands (secretions into interstitial fluid) • More information in later chapter 2. Exocrine glands (secretions into ducts that open onto epithelial surface) © 2011 Pearson Education, Inc. Module 4.6: Glandular epithelia • Exocrine glands • Three types of secretion 1. Merocrine secretion (meros, part) • Product released from secretory vesicles by exocytosis • Most common type of secretion • Mucin • Merocrine secretion that mixes with water to form mucus • Used as lubricant, protective barrier, and trap for foreign particles and microorganisms © 2011 Pearson Education, Inc. Module 4.6: Glandular epithelia • Exocrine glands • Three types of secretion (continued) 2. Apocrine secretion (apo-, off) • Loss of apical surface and cytoplasm with secretion • Example: mammary glands • Merocrine and apocrine secretions in milk 3. Holocrine secretion (holos, entire) • Entire cell bursts, releasing secretion and killing cell • Replaced by stem cell division Animation: Mechanisms of Glandular Secretion © 2011 Pearson Education, Inc. Mucin is a merocrine secretion that mixes with water to form mucus. Mucus is an effective lubricant, a protective barrier, and a sticky trap for foreign particles and microorganisms. Secretory vesicle (containing mucin) Golgi apparatus Nucleus TEM x 3120 The three types of secretion by glandular epithelial cells In merocrine secretion (MER-u-krin; meros, part), the product is released from secretory vesicles by exocytosis. This is the most common mode of secretion. Breaks down Regrowth Salivary gland Secretion Golgi apparatus Mammary gland Apocrine secretion (AP-ō-krin; apo-, off) involves the loss of cytoplasm as well as the secretory product. The apical portion of the cytoplasm becomes packed with secretory vesicles and is then shed. Milk production in the mammary glands involves a combination of merocrine and apocrine secretions. Cells burst, releasing cytoplasmic contents. Hair Cells produce secretion, increasing in size. Sebaceous gland Hair follicle Start Cell division replaces lost cells. Stem cell Holocrine secretion (HOL-ō-krin; holos, entire), by contrast, destroys the gland cell. During holocrine secretion, the entire cell becomes packed with secretory products and then bursts, releasing the secretion and killing the cell. Further secretion depends on the replacement of destroyed gland cells by the division of stem cells. © 2011 Pearson Education, Inc. Figure 4.6 1 Module 4.6: Glandular epithelia • Multicellular exocrine gland structure • Gland classification • Based on duct structure • Simple (single duct that does not divide) • Compound (duct divides one or more times) • Based on structure of secretory area • Tubular (glandular cells form tubes) • Alveolar or acinar (glandular cells form sacs) • Tubuloalveolar (glandular cells form tubes and sacs) © 2011 Pearson Education, Inc. A gland is branched if several secretory areas (tubular or acinar) share a duct. Note that “branched” refers to the glandular areas and not to the duct. Simple exocrine glands Duct Gland cells SIMPLE TUBULAR Examples: • Intestinal glands SIMPLE COILED TUBULAR Examples: • Merocrine sweat glands SIMPLE BRANCHED TUBULAR Examples: • Gastric glands • Mucous glands of esophagus, tongue, duodenum Glands whose glandular cells form tubes are tubular; the tubes may be straight or coiled. SIMPLE ALVEOLAR (ACINAR) Examples: • A stage in the embryonic development of simple branched glands SIMPLE BRANCHED ALVEOLAR Examples: • Sebaceous (oil) glands Glands whose glandular cells form sac-like pockets are alveolar (al-VĒ-ō-lar; alveolus, sac) or acinar (AS-i-nar; acinus, chamber). Figure 4.6 © 2011 Pearson Education, Inc. 2 Compound exocrine glands Glands whose secretory cells form both tubes and sacs are called tubuloalveolar. COMPOUND TUBULAR COMPOUND ALVEOLAR (ACINAR) COMPOUND TUBULOALVEOLAR Examples: • Mucous glands (in mouth) • Bulbo-urethral glands (in male reproductive system) • Seminiferous tubules of testes Examples: Examples: • Salivary glands • Glands of respiratory passages • Pancreas • Mammary glands Figure 4.6 © 2011 Pearson Education, Inc. 3 Module 4.6: Glandular epithelia • Unicellular glands • Individual, scattered secretory cells (mucous cells) • Secrete mucin • Apical cytoplasm filled with large secretory vesicles © 2011 Pearson Education, Inc. A mucous cell in a ciliated columnar epithelium Mucin Golgi apparatus Nucleus Mucous cell Figure 4.6 © 2011 Pearson Education, Inc. 4 Module 4.6 Review a. Name the two primary types of glands. b. What mode of secretion occurs in the secretory cells of sebaceous glands, which fill with secretions and then rupture, releasing their contents? c. Which type of gland has no ducts to carry the glandular secretions, and the gland’s secretions are released directly into the interstitial fluid? © 2011 Pearson Education, Inc. Section 2: Connective Tissues • Learning Outcomes • 4.7 Describe the structure, function, and locations of areolar connective tissue, adipose tissue, and reticular tissue. • 4.8 Describe the structure, function, and locations of dense connective tissues and fluid connective tissues. • 4.9 Describe the structure, function, and locations of cartilage. © 2011 Pearson Education, Inc. Section 2: Connective Tissues • Learning Outcomes • 4.10 Describe the structure and function of bone. • 4.11 Describe the arrangements of epithelial and connective tissues in the four types of membranes. © 2011 Pearson Education, Inc. Section 2: Connective Tissues • Connective tissues • • • Vary in appearance and function Throughout body but never exposed to outside Many have blood vessels and sensory receptors • All share three basic components 1. Specialized cells 2. Extracellular protein fibers 3. Fluid (ground substance) • Extracellular fibers and fluid make up matrix that surrounds cells • Fewer cells and more extracellular material compared to epithelial cells © 2011 Pearson Education, Inc. The three types of connective tissue and examples of each Connective Tissue The various types of connective tissue are situated throughout the body but they are never exposed to the outside environment. Many types of connective tissue are highly vascular (that is, they have many blood vessels) and contain sensory receptors that detect pain, pressure, temperature, and other stimuli. Connective Tissue Proper Connective tissue proper includes those connective tissues with many types of cells and extracellular fibers in a syrupy ground substance. Fluid Connective Tissues Supporting Connective Tissues Fluid connective tissues have distinctive populations of cells suspended in a watery matrix that contains dissolved proteins. Supporting connective tissues differ from connective tissue proper in having a less diverse cell population and a matrix containing much more densely packed fibers. Supporting connective tissues protect soft tissues and support the weight of part or all of the body. Loose Dense Blood Lymph Cartilage Bone Fibers create loose, open framework Fibers densely packed • dense regular • dense irregular • elastic Flows within cardiovascular system Flows within lymphatic system Solid, rubbery matrix Solid, crystalline matrix • areolar tissue • adipose tissue • reticular tissue • hyaline cartilage • elastic cartilage • fibrous cartilage Figure 4 Section 2 © 2011 Pearson Education, Inc. Section 2: Connective Tissues • Connective tissue types • Connective tissue proper (many types of cells, fibers with syrupy ground substance) • Loose (fibers create loose, open framework) • Dense (fibers densely packed) • Fluid connective tissues (watery matrix) • Blood (in cardiovascular system) • Lymph (in lymphatic system) © 2011 Pearson Education, Inc. Section 2: Connective Tissues • Connective tissue types (continued) • Supporting connective tissues (less diverse cells, matrix with densely packed fibers) • Cartilage (solid, rubbery matrix) • Bone (solid, crystalline matrix) © 2011 Pearson Education, Inc. Figure 4 Section 2 © 2011 Pearson Education, Inc. Module 4.7: Loose connective tissues • Connective tissue proper components • Extracellular protein fibers • Viscous ground substance • Two classes of cells 1. Fixed • Stationary • Function in maintenance, repair, and storage 2. Wandering • Move throughout tissue • Function in defense and repair © 2011 Pearson Education, Inc. Module 4.7: Loose connective tissues • Connective tissue proper components (continued) • Extracellular protein fibers (continued) • Reticular fibers (strong and form branching network) • Collagen fibers (thick, very strong) • Elastic fibers (slender, very stretchy) © 2011 Pearson Education, Inc. Module 4.7: Loose connective tissues • Connective tissue proper components (continued) • Ground substance • Clear • Colorless • Viscous (syrupy) due to presence of proteoglycans and glycoproteins © 2011 Pearson Education, Inc. Module 4.7: Loose connective tissues • Connective tissue proper components (continued) • Fixed cells • Melanocytes (synthesize melanin pigment) • Fixed macrophage (engulfs cell debris and pathogens) • Mast cells (stimulate inflammation and mobilize defenses) • Fibroblasts (synthesize extracellular fibers) • Adipocytes (store lipid reserves) © 2011 Pearson Education, Inc. Module 4.7: Loose connective tissues • Connective tissue proper components (continued) • Wandering cells • Plasma cells (immune cell producing antibodies) • Free macrophages (engulf debris and pathogens) • Mesenchymal cells (stem cells that aid tissue repair) • Neutrophils and eosinophils (phagocytic blood cells) • Lymphocytes (immune system cells) © 2011 Pearson Education, Inc. The components of areola tissue Fibers Reticular fibers are strong and form a branching network. Collagen fibers are thick, straight or wavy, and often form bundles. They are very strong and resist stretching. Elastic fibers are slender, unbranching, and very stretchy. They recoil to their original length after stretching or distortion. Fixed Cells Wandering Cells A melanocyte is a fixed pigment cell that synthesizes melanin, a brownish-yellow pigment. A plasma cell is an active, mobile immune cell that produces antibodies. A fixed macrophage is a stationary phagocytic cell that engulfs cell debris and pathogens. Free macrophages are wandering phagocytic cells that patrol the tissue, engulfing debris or pathogens. Mast cells are fixed cells that stimulate local inflammation and mobilize tissue defenses. Mesenchymal cells are mobile stem cells that participate in the repair of damaged tissues. Fibroblasts are fixed cells that synthesize the extracellular fibers of the connective tissue. Neutrophils and eosinophils are small, mobile, phagocytic blood cells that enter tissues during infection or injury. Adipocytes (fat cells) are fixed cells that store lipid reserves in large intracellular vesicles. © 2011 Pearson Education, Inc. Red blood cell in vessel Ground substance fills the spaces between cells and surrounds connective tissue fibers. In all forms of connective tissue proper, ground substance is clear, colorless, and viscous (syrupy) due to the presence of proteoglycans and glycoproteins. Lymphocytes are mobile cells of the immune system. Figure 4.7 1 Module 4.7: Loose connective tissues • Three types of loose connective tissues 1. Areolar tissue • Most common connective tissue proper • Packing material of the body • Has all connective tissue proper cell types 2. Adipose tissue • Found deep to skin in various areas of body • Mostly cells (adipocytes) © 2011 Pearson Education, Inc. The structure of adipose tissue deep to the skin Adipocytes LM x 340 Figure 4.7 © 2011 Pearson Education, Inc. 2 Module 4.7: Loose connective tissues • Three types of loose connective tissues (continued) 3. Reticular tissue • Found in liver, kidney, spleen, lymph nodes, and bone marrow • Provides support and resists distortion • Many reticular fibers forming network (stroma) © 2011 Pearson Education, Inc. The structure of reticular tissue in the liver Reticular fibers LM x 375 Figure 4.7 © 2011 Pearson Education, Inc. 3 Module 4.7 Review a. Identify the types of cells found in connective tissue proper. b. Which type of connective tissue contains primarily lipids? c. Describe the role of fibroblasts in connective tissue. © 2011 Pearson Education, Inc. Module 4.8: Dense and fluid connective tissues • Dense connective tissues • Most volume occupied by extracellular fibers • Three types 1. Dense regular connective tissue • Found in tendons, ligaments, organ cords • Has parallel collagen fibers 2. Dense irregular connective tissue • Found covering visceral organs; in superficial layers of bones, cartilages, and peripheral nerves; in dermis • No consistent pattern of fiber arrangement © 2011 Pearson Education, Inc. Module 4.8: Dense and fluid connective tissues • Dense connective tissues (continued) • Three types (continued) 3. Elastic tissue • More elastic fibers than collagen • Is springy and resilient • Found between vertebrae, in walls of large blood vessels, erectile tissues of penis © 2011 Pearson Education, Inc. The three types of dense connective tissues Collagen fiber Fibroblast nuclei LM x 440 Dense regular connective tissue in a tendon from the triceps muscle Collagen fiber bundles LM x 111 Dense irregular connective tissue from the dermis Elastic fibers Fibroblast nuclei LM x 887 Elastic tissue from a ligament between vertebrae © 2011 Pearson Education, Inc. Figure 4.8 1 – 3 Module 4.8: Dense and fluid connective tissues • Fluid connective tissues • Fluid matrix with many suspended proteins • Normally without fibers • Types 1. Blood • Components • Watery matrix (plasma) • Cells and cell fragments (formed elements) 2. Lymph • Components • Watery matrix (lymph) • Cells (mainly lymphocytes) © 2011 Pearson Education, Inc. Module 4.8: Dense and fluid connective tissues • Formed elements of blood • Red blood cells (transport oxygen) • White blood cells (bodily defense) • • Monocytes (large phagocytes) • Lymphocytes (uncommon in blood) • Eosinophils/neutrophils (small phagocytes) • Basophils (promote inflammation) Platelets (involved in clotting response) © 2011 Pearson Education, Inc. Module 4.8: Dense and fluid connective tissues • Fluid connective tissue locations and functions • Blood • • Normally moved by heart through blood vessels • Arteries (away from heart) • Capillaries (smallest vessels; sites of exchange) • Veins (toward heart) Exchanges water and solutes between plasma and interstitial fluid © 2011 Pearson Education, Inc. The formed elements in blood, a fluid connective tissue with a watery matrix called plasma Red Blood Cells White Blood Cells Platelets Red blood cells are formed elements responsible for the transport of oxygen (and, to a lesser degree, of carbon dioxide) in the blood. White blood cells are formed elements that help defend the body from infection and disease. Platelets are formed elements consisting of membrane-enclosed packets of cytoplasm. Red blood cells account for roughly half the volume of whole blood and give blood its color. Monocytes are phagocytes similar to the free macrophages in other tissues. Eosinophil Lymphocytes are uncommon in the blood but they are the dominant cell type in lymph, the second type of fluid connective tissue. Neutrophil Basophil Eosinophils and neutrophils are phagocytes. Basophils promote inflammation much like mast cells in other connective tissues. These cell fragments are involved in the clotting response that seals leaks in damaged or broken blood vessels. Figure 4.8 © 2011 Pearson Education, Inc. 4 Module 4.8: Dense and fluid connective tissues • Fluid connective tissue locations and functions (continued) • Lymph • Located in lymphatic vessels • Collected from interstitial fluid • Returned to blood at large veins near heart • Functions to maintain solute levels, blood volume, and alert immune system of infection © 2011 Pearson Education, Inc. Capillaries are the smallest and most delicate blood vessels. All exchange between the blood and interstitial fluid occurs at capillaries. Start Arteries carry blood away from the heart and into the tissues of the body. Heart Water and solutes from bloodstream At capillary networks, blood pressure forces water and small solutes out of the bloodstream and into the surrounding interstitial fluid. Lymph forms as interstitial fluid enters lymphatic vessels. Veins carry blood from capillary beds to the heart. Lymphatic vessels form a network that returns lymph to large veins near the heart. The continuous circulation of extracellular fluid, including the fluid connective tissue called lymph Figure 4.8 © 2011 Pearson Education, Inc. 5 Module 4.8 Review a. Which two types of connective tissue have a liquid matrix? b. Lack of vitamin C in the diet interferes with the ability of fibroblasts to produce collagen. How might this affect connective tissue function? c. Summarize the role of extracellular fluid in maintaining homeostasis. © 2011 Pearson Education, Inc. Module 4.9: Cartilage • Cartilage • Matrix is firm gel containing polysaccharide derivatives (chondroitin sulfates [chondros, cartilage]) • Forms complexes with proteins producing proteoglycans • Cells (chondrocytes) • Only cells in cartilage matrix • Occupy small chambers (lacunae [lacus, lake]) © 2011 Pearson Education, Inc. Module 4.9: Cartilage • Cartilage properties • Depend on matrix proteoglycans as well as type and abundance of extracellular fibers • Set apart from surrounding tissues by perichondrium (peri-, around) • Two layers of perichondrium 1. Outer layer of dense regular connective tissue • Mechanical support, protection, attachment 2. Inner cellular layer • © 2011 Pearson Education, Inc. Where cartilage growth and maintenance occur The perichondrium, which separates cartilage from surrounding tissues Perichondrium Hyaline cartilage LM x 250 Figure 4.9 © 2011 Pearson Education, Inc. 4 Module 4.9: Cartilage • Three types 1. Hyaline cartilage • Found between ribs and sternum, covering bones in mobile joints, certain areas of respiratory system • Stiff but flexible support and reduces friction 2. Elastic cartilage • Supports external ear and other smaller internal structures • Increased flexibility © 2011 Pearson Education, Inc. Module 4.9: Cartilage • Three types (continued) 3. Fibrous cartilage • Found within knee joint, between pubic bones of pelvis, in intervertebral discs • Resists compression, prevents bone-to-bone contact, and limits relative movement © 2011 Pearson Education, Inc. The three types of cartilage Chondrocytes in lacunae Matrix LM x 500 Hyaline cartilage from shoulder joint Chondrocyte in lacuna Elastic fibers in matrix LM x 358 Elastic cartilage from external ear Collagen fibers in matrix Chondrocytes LM x 400 Fibrous cartilage from intervertebral disc © 2011 Pearson Education, Inc. Figure 4.9 1 – 3 Module 4.9: Cartilage • Cartilage growth • Two types 1. Appositional growth (at cartilage surface) • Chondroblasts (immature chondrocytes) divide in cellular layer of perichondrium • Chondroblasts secrete new matrix • Once surrounded by matrix, chondroblasts mature into chondrocytes © 2011 Pearson Education, Inc. Module 4.9: Cartilage • Cartilage growth • Two types (continued) 2. Interstitial growth (within cartilage) • Chondrocytes divide within a lacuna • Daughter cells secrete additional matrix and move apart • Both types occur during development • Normally no growth and repair in adults • With slight damage or with hormonal stimulation, some appositional growth possible © 2011 Pearson Education, Inc. The types of cartilage growth Appositional Growth Fibroblasts Dividing stem cell Perichondrium New matrix Chondroblasts Mature chondrocytes Older matrix In appositional growth, the cartilage enlarges by the addition of cartilage to the outer surface. Cells in the cellular layer of the perichondrium differentiate into chrondroblasts (immature chrondrocytes). The chondroblasts secrete new matrix and become separated from each other. Divisions of stem cells in the perichondrium continuously produce additional chondroblasts. Meanwhile, chondroblasts completely surrounded by matrix gradually mature into chondrocytes. Interstitial Growth New matrix Matrix Chondrocyte Lacuna In interstitial growth, the cartilage expands from within. A chondrocyte undergoes division within a lacuna surrounded by cartilage matrix. As daughter cells secret additional matrix, they move apart, expanding the cartilage from within. Figure 4.9 © 2011 Pearson Education, Inc. 5 Module 4.9 Review a. Mature cartilage cells are called __________. b. Which connective tissue fiber is characteristic of the cartilage supporting the ear? c. If a person has a herniated intervertebral disc, which type of cartilage has been damaged? © 2011 Pearson Education, Inc. Module 4.10: Bone • Osseous tissue (os, bone) structure • Bony matrix • Small volume of ground substance • 2/3 of matrix is calcium salts (provide strength) • Mostly calcium phosphate • Some calcium carbonate • Many collagen fibers (provide flexibility) © 2011 Pearson Education, Inc. Module 4.10: Bone • Comparison of cartilage and bone • Both support and protect • Cartilage is avascular; bone is highly vascular • Cartilage cannot grow/repair; extensive remodeling and repair in bone © 2011 Pearson Education, Inc. Figure 4.10 © 2011 Pearson Education, Inc. 2 Module 4.10: Bone • Typical long bone structure • Hollow with two types of bone 1. Spongy bone • Lines internal cavity 2. Compact bone • Outer layer of bone © 2011 Pearson Education, Inc. The structure of a long bone, which consists of compact bone and spongy bone In compact bone the matrix is organized in concentric layers around branches of blood vessels within the bone. Compact bone Compact bone also has a superficial layer of bone that was deposited during appositional growth of the bone. Because the matrix is solid and calcified, interstitial growth cannot occur in bone. Unlike cartilage, bone is highly vascular. Large vessels outside the bone are connected to smaller vessels that supply areas of compact bone and the soft tissues that fill the interior cavity. Spongy bone Figure 4.10 © 2011 Pearson Education, Inc. 1 Module 4.10: Bone • Compact bone structure • Matrix organized in concentric layers • Organized into functional units (osteons) • Central canal contains blood vessels in center • Cells (osteocytes) located between layers • Canaliculi (little canals) connect osteocytes • Superficial layer of bone prevents interstitial growth © 2011 Pearson Education, Inc. Module 4.10: Bone • Compact bone structure (continued) • Surrounded by periosteum • Two layers 1. Outer fibrous layer allows attachment of ligaments 2. Inner cellular layer allows appositional growth and repair © 2011 Pearson Education, Inc. The structural features of compact bone, including its functional unit, the osteon Layers of the Periosteum The fibrous layer assists in the attachment of a bone to surrounding tissues and to associated tendons and ligaments. Except in joint cavities, where they are covered by a layer of hyaline cartilage, bone surfaces are sheathed by a periosteum (per-ē-OS-tē-um) composed of fibrous (outer) and cellular (inner) layers. The cellular layer functions in appositional bone growth and participates in repairs after an injury. Lacunae in the matrix contain osteocytes (OS-tē- ō-sīts), or bone cells. The lacunae are typically organized around blood vessels that branch through the bony matrix. Layers of matrix separate the lacunae. These layers are oriented along the main axis of the bone. Canaliculi (kan-a- LIK-ū-lē; little canals) are fine passageways that form a branching network for the exchange of materials between blood vessels and osteocytes. This is important because diffusion cannot occur through the calcified matrix of bone. A central canal at the center of an osteon contains the blood vessels that provide oxygen and nutrients to the osteocytes. Matrix Osteon Lacunae Canaliculi LM x 320 Figure 4.10 © 2011 Pearson Education, Inc. 3 – 4 Module 4.10 Review a. Mature bone cells in lacunae are called ____________. b. Distinguish between the two types of supporting connective tissues with respect to their characteristic fibers. c. Explain why bone does not undergo interstitial growth. © 2011 Pearson Education, Inc. Module 4.11: Membranes and fasciae • Membranes • Line or cover body surfaces • Consist of epithelium supported by connective tissue • Four types 1. Mucous membranes • Line organs that communicate to exterior • Must be kept moist to facilitate movement, absorption, or secretion • • Lubricated by mucus or bodily fluids Supported by areolar connective tissue (lamina propria) © 2011 Pearson Education, Inc. Module 4.11: Membranes and fasciae • Membranes (continued) • Four types (continued) 2. Serous membranes • Mesothelium supported by areolar connective tissue • Delicate and never connected to exterior • Transudate (liquid layer) coats surface • Three line subdivisions of ventral body cavity • Pleura (pleural cavity and lungs) • Peritoneum (peritoneal cavity and visceral organs) • Pericardium (pericardial cavity and heart) © 2011 Pearson Education, Inc. Module 4.11: Membranes and fasciae • Membranes (continued) • Four types (continued) 3. Cutaneous membrane • Covers surface of body • = Skin • Relatively thick, waterproof, and dry comparatively © 2011 Pearson Education, Inc. Module 4.11: Membranes and fasciae • Membranes (continued) • Four types (continued) 4. Synovial membranes • Line mobile joint cavities • Similar to epithelia but not • Develops within connective tissue • No basal lamina • Gaps between cells (up to 1 mm) • Exchange fluid (synovial fluid) and solutes with cardiovascular capillaries © 2011 Pearson Education, Inc. Module 4.11: Membranes and fasciae • Fasciae • Connective tissue layers and wrappings • Support and surround organs • Three types 1. Superficial fascia • Under skin • Consists of areolar and adipose tissue 2. Deep fascia • Continuous with capsules, ligaments, and other connective tissue structures • Consists of dense irregular connective tissue © 2011 Pearson Education, Inc. Module 4.11: Membranes and fasciae • Fasciae (continued) • Three types (continued) 3. Subserous fascia • Between serous membranes and deep fascia • Consists entirely of areolar tissue © 2011 Pearson Education, Inc. Connective Tissue Framework of Body Body wall Body cavity Skin The Superficial Fascia The Deep Fascia The Subserous Fascia • Lies between the skin and underlying organs • Forms a strong, fibrous internal framework • Lies between serous membranes and deep fascia • Consists of areolar tissue and adipose tissue • Consists of dense irregular connective tissue • Consists entirely of areolar tissue • Is continuous with or bound to capsules, ligaments, and other connective tissue structures Serous membrane lining body cavity Rib Cutaneous membrane of the skin The structure and function of fasciae Figure 4.11 © 2011 Pearson Education, Inc. 1 Module 4.11 Review a. Name the four types of membranes found in the body. b. Which cavities in the body are lined by serous membranes? c. A sheet of tissue has many layers of collagen fibers that run in different directions in successive layers. Which type of tissue is this? © 2011 Pearson Education, Inc. Section 3: Muscle Tissue and Neural Tissue • Learning Outcomes • 4.12 Specify the functions of muscle tissue and neural tissue. • 4.13 CLINICAL MODULE Describe the roles of inflammation and regeneration in response to tissue injury. © 2011 Pearson Education, Inc. Section 3: Muscle Tissue and Neural Tissue • Muscle and neural tissue contribute significantly to various systems in the body • These two tissue types contribute the most (muscle) and least (neural) to body weight © 2011 Pearson Education, Inc. Epithelial tissue 3% Connective tissue 45% Neural tissue 2% Muscle tissue 50% The relative contributions of muscle tissue and neural tissue to the weight of the body The three types of muscle tissue Muscle Tissue Skeletal Muscle Tissue Cardiac Muscle Tissue Smooth Muscle Tissue Skeletal muscle tissue moves the body by pulling on bones of the skeleton, making it possible for us to walk, dance, bite an apple, or play the ukulele. Cardiac muscle tissue contractions move blood through the blood vessels. Smooth muscle tissue contractions move fluids and solids along the digestive tract and regulate the diameters of small arteries, among other functions. Figure 4 Section 3 © 2011 Pearson Education, Inc. Module 4.12: Muscle tissue for contraction and neural tissue for communication • Muscle tissue • All functions involve movement • Movement of body • Movement of blood around cardiovascular system • Movement of materials along digestive tract • Three types 1. Skeletal muscle tissue 2. Cardiac muscle tissue 3. Smooth muscle tissue © 2011 Pearson Education, Inc. Module 4.12: Muscle tissue for contraction and neural tissue for communication • Muscle tissue • Three types 1. Skeletal muscle tissue • Found in skeletal muscle • Cells are long, cylindrical, banded (striated), and have multiple nuclei (multinucleate) • Functions • Move skeleton • Guard organ entrances for digestive, respiratory, and urinary system • Generate heat • Protect internal organs © 2011 Pearson Education, Inc. Module 4.12: Muscle tissue for contraction and neural tissue for communication • Muscle tissue (continued) • Three types (continued) 2. Cardiac muscle tissue • Found only in heart • Cells are short, branched, and have a single nucleus • • Interconnected with special junctions (intercalated discs) Functions to move blood and maintain blood pressure © 2011 Pearson Education, Inc. Module 4.12: Muscle tissue for contraction and neural tissue for communication • Muscle tissue (continued) • Three types (continued) 3. Smooth muscle tissue • Found throughout body (skin, blood vessel walls, many organs of various systems) • Cells are short, spindle-shaped, nonstriated, have a single nucleus • Functions • Move food, urine, and reproductive secretions • Control diameter of respiratory passageways and blood vessels © 2011 Pearson Education, Inc. The structure and function of the three types of muscle tissue Nuclei Muscle fiber Striations LM x 180 Skeletal muscles move or stabilize the position of the skeleton; guard entrances and exits to the digestive, respiratory, and urinary tracts; generate heat; and protect internal organs. Nucleus Cardiac muscle cells Intercalated discs Striations LM x 450 Cardiac muscle moves blood and maintains blood pressure. Smooth muscle cell Nucleus LM x 235 Smooth muscle moves food, urine, and reproductive tract secretions; controls diameter of respiratory passageways and regulates diameter of blood vessels. © 2011 Pearson Education, Inc. Figure 4.12 1 - 3 Module 4.12: Muscle tissue for contraction and neural tissue for communication • Neural tissue (nervous tissue) • Specialized for conduction of electrical impulses • 98% found in brain and spinal cord • Two basic types of cells 1. Neurons (neuros, nerve) 2. Neuroglia or glial cells (glia, glue) • Various supporting cells © 2011 Pearson Education, Inc. Module 4.12: Muscle tissue for contraction and neural tissue for communication • Neurons • Transfer information around body and perform information processing • = Conscious and unconscious thought in the brain • Vary in size and shape • Longest cells in body are neurons (up to 1 meter) © 2011 Pearson Education, Inc. Module 4.12: Muscle tissue for contraction and neural tissue for communication • Neuron structure • Dendrites (dendron, tree) • Receive information • Axon • Conducts information to other cells • Also called nerve fibers • Cell body • Contains large nucleus and other organelles • Cell control center and site of information processing • Most lack centrioles and cannot divide © 2011 Pearson Education, Inc. The shapes of different types of neuroglia Figure 4.12 © 2011 Pearson Education, Inc. 5 Module 4.12: Muscle tissue for contraction and neural tissue for communication • Neuroglia • Several different structural types with associated functions • Maintain physical structure of neural tissue • Repair neural tissue framework after injury • Perform phagocytosis • Provide nutrients to neurons • Regulate the composition of the interstitial fluid surrounding neurons © 2011 Pearson Education, Inc. Module 4.12 Review a. Identify the three types of muscle tissue in the body. b. Which type of muscle tissue has small, tapering cells with single nuclei and no obvious striations? c. Irregularly shaped cells with many fibrous projections, some several centimeters long, are probably which type of cell? © 2011 Pearson Education, Inc. Module 4.13 CLINICAL MODULE: Response to injury • Organs are comprised of different tissue types • Damage to an organ affects many tissues • Tissues respond in a coordinated way to restore homeostasis • Each tissue has a different ability to regenerate • Epithelial, connective (except cartilage), and smooth muscle regenerate well • Other muscle types and neural tissue regenerate poorly, if at all • Scar tissue replaces tissues that do not regenerate (= fibrosis) © 2011 Pearson Education, Inc. Module 4.13 CLINICAL MODULE: Response to injury • Injury • Exposure to pathogens and toxins (infection) • Stimulates mast cell activation, which causes inflammation • Inflammation • Familiar symptoms of swelling, redness, warmth, and pain • Occurs in connective tissue • So can occur anywhere in body because part of all organs • Leads to increased oxygen/nutrients, phagocytosis, and removal of toxins and wastes © 2011 Pearson Education, Inc. Module 4.13 CLINICAL MODULE: Response to injury • Regeneration • Repair after tissue stabilized and inflammation ends • Fibroblasts secrete collagen fibers to stabilize area (= scar tissue) • Gradually remodeled or replaced • Normal conditions restored © 2011 Pearson Education, Inc. Inflammation The events that occur during tissue injury and repair Injury When a tissue is injured, a general defense mechanism is activated. Exposure to Pathogens and Toxins Mast Cell Activation An injured tissue contains an abnormal concentration of pathogens, toxins, waste products, and the chemicals from injured cells. When an injury damages connective tissue, mast cells release a variety of chemicals. This process, called mast cell activation, stimulates inflammation. stimulates Histamine Mast cell Heparin Prostaglandins Figure 4.13 © 2011 Pearson Education, Inc. 1 Injury Mast Cell Activation Regeneration, the repair to the injured tissue once inflammation has subsided. Regeneration inhibits mast cell activation Regeneration Normal tissue conditions restored As tissue conditions return to normal, fibroblasts move into the area, laying down a network of collagen fibers that stabilizes the injury site. This process produces a dense, collagenous framework known as scar tissue. Over time, scar tissue is usually “remodeled” and gradually assumes a more normal appearance. Over a period of hours to days, the cleanup process generally succeeds in eliminating the inflammatory stimuli. Inflammation Scar tissue Figure 4.13 © 2011 Pearson Education, Inc. 3 Module 4.13 CLINICAL MODULE: Review a. Identify the two processes in the response to tissue injury. b. What are the four indications of inflammation that occur following an injury? c. Why can inflammation occur in any organ in the body? © 2011 Pearson Education, Inc.