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Tissues o Structures with discrete structural and functional properties o Tissues in combination form organs, such as the heart or liver o Organs can be grouped into 11 organ systems Tissue o Are collections of cells and cell products that perform specific, limited functions o Four types of tissue 1. Epithelial tissue 2. Connective tissue 3. Muscle tissue 4. Neural tissue © 2012 Pearson Education, Inc. Epithelial Tissue o Covers exposed surfaces o Lines internal passageways o Forms glands Connective Tissue o Fills internal spaces o Supports other tissues o Transports materials o Stores energy © 2012 Pearson Education, Inc. Muscle Tissue o Specialized for contraction o Skeletal muscle, heart muscle, and walls of hollow organs Neural Tissue o Carries electrical signals from one part of the body to another © 2012 Pearson Education, Inc. Epithelia o Layers of cells covering internal or external surfaces Glands o Structures that produce secretions © 2012 Pearson Education, Inc. Characteristics of Epithelia o Cellularity (cell junctions) o Polarity (apical and basal surfaces) o Attachment (basement membrane or basal lamina) o Avascularity o Regeneration © 2012 Pearson Education, Inc. Cilia Microvilli Apical surface Golgi apparatus Nucleus Mitochondria Basement membrane Basolateral surfaces Functions of Epithelial Tissue 1. Provide Physical Protection 2. Control Permeability 3. Provide Sensation 4. Produce Specialized Secretions (glandular epithelium) © 2012 Pearson Education, Inc. Specializations of Epithelial Cells 1. Move fluids over the epithelium (protection) 2. Move fluids through the epithelium (permeability) 3. Produce secretions (protection and messengers) Polarity 1. Apical surfaces • Microvilli increase absorption or secretion • Cilia (ciliated epithelium) move fluid 2. Basolateral surfaces © 2012 Pearson Education, Inc. Maintaining the Integrity of Epithelia 1. Intercellular connections 2. Attachment to the basement membrane 3. Epithelial maintenance and repair © 2012 Pearson Education, Inc. Intercellular Connections o Cell junctions • Form bonds with other cells or extracellular material 1. Tight junctions 2. Gap junctions 3. Desmosomes © 2012 Pearson Education, Inc. Attachment to the Basement Membrane o Clear layer (lamina lucida) • Thin layer • Secreted by epithelia • Barrier to proteins o Dense layer (lamina densa) • Thick fibers • Produced by connective tissue • Strength and filtration © 2012 Pearson Education, Inc. Tight junction Adhesion belt Terminal web Spot desmosome Gap junctions Hemidesmosome This is a diagrammatic view of an epithelial cell, showing the major types of intercellular connections. Interlocking junctional proteins Tight junction Terminal web Adhesion belt A tight junction is formed by the fusion of the outer layers of two plasma membranes. Tight junctions prevent the diffusion of fluids and solutes between the cells. A continuous adhesion belt lies deep to the tight junction. This belt is tied to the microfilaments of the terminal web. Embedded proteins (connexons) Gap junctions permit the free diffusion of ions and small molecules between two cells. Intermediate filaments Cell adhesion molecules (CAMs) Dense area Proteoglycans A spot desmosome ties adjacent cells together. Epithelial Maintenance and Repair o Epithelia are replaced by division of germinative cells (stem cells) o Near basement membrane © 2012 Pearson Education, Inc. Singular = Epithelium; Plural = Epithelia Classes of Epithelia 1. 2. Based on shape • Squamous epithelia — thin and flat • Cuboidal epithelia — square shaped • Columnar epithelia — tall, slender rectangles Based on layers • Simple epithelium — single layer of cells • Stratified epithelium — several layers of cells © 2012 Pearson Education, Inc. Squamous Epithelia o Simple squamous epithelium • Absorption and diffusion o Mesothelium • Lines body cavities o Endothelium • Lines heart and blood vessels © 2012 Pearson Education, Inc. Simple Squamous Epithelium LOCATIONS: Mesothelia lining ventral body cavities; endothelia lining heart and blood vessels; portions of kidney tubules (thin sections of nephron loops); inner lining of cornea; alveoli of lungs FUNCTIONS: Reduces friction; controls vessel permeability; performs absorption and secretion Cytoplasm Nucleus Connective tissue Lining of peritoneal cavity LM 238 Squamous Epithelia o Stratified squamous epithelium • Protects against attacks • Keratin protein adds strength and water resistance © 2012 Pearson Education, Inc. Stratified Squamous Epithelium LOCATIONS: Surface of skin; lining of mouth, throat, esophagus, rectum, anus, and vagina FUNCTIONS: Provides physical protection against abrasion, pathogens, and chemical attack Squamous superficial cells Stem cells Basement membrane Connective tissue Surface of tongue LM 310 Cuboidal Epithelia o Simple cuboidal epithelium • Secretion and absorption o Stratified cuboidal epithelia • Sweat ducts and mammary ducts © 2012 Pearson Education, Inc. Simple Cuboidal Epithelium LOCATIONS: Glands; ducts; portions of kidney tubules; thyroid gland Connective tissue FUNCTIONS: Limited protection, secretion, absorption Nucleus Cuboidal cells Basement membrane Kidney tubule LM 650 Stratified Cuboidal Epithelium LOCATIONS: Lining of some ducts (rare) FUNCTIONS: Protection, secretion, absorption Lumen of duct Stratified cuboidal cells Basement membrane Nuclei Connective tissue Sweat gland duct LM 500 Transitional Epithelium o Tolerates repeated cycles of stretching and recoiling and returns to its previous shape without damage o Appearance changes as stretching occurs o Situated in regions of the urinary system (e.g., urinary bladder) © 2012 Pearson Education, Inc. Transitional Epithelium LOCATIONS: Urinary bladder; renal pelvis; ureters FUNCTIONS: Permits expansion and recoil after stretching Epithelium (relaxed) Basement membrane Empty bladder Connective tissue and smooth muscle layers LM 400 Epithelium (stretched) Full bladder Urinary bladder Basement membrane Connective tissue and smooth muscle layers LM 400 LM 400 Columnar Epithelia o Simple columnar epithelium • Absorption and secretion o Pseudostratified columnar epithelium • Cilia movement o Stratified columnar epithelium • Protection © 2012 Pearson Education, Inc. Simple Columnar Epithelium LOCATIONS: Lining of stomach, intestine, gallbladder, uterine tubes, and collecting ducts of kidneys FUNCTIONS: Protection, secretion, absorption Microvilli Cytoplasm Nucleus Intestinal lining Basement membrane Loose connective tissue LM 350 Pseudostratified Ciliated Columnar Epithelium LOCATIONS: Lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract Cilia Cytoplasm FUNCTIONS: Protection, secretion, move mucus with cilia Nuclei Basement membrane Trachea Loose connective tissue LM 350 Stratified Columnar Epithelium LOCATIONS: Small areas of the pharynx, epiglottis, anus, mammary glands, salivary gland ducts, and urethra FUNCTION: Protection Lumen Loose connective tissue Deeper basal cells Superficial columnar cells Lumen Cytoplasm Nuclei Salivary gland duct Basement membrane LM 175 Glandular Epithelia o Endocrine glands • Release hormones • Into interstitial fluid • No ducts o Exocrine glands • Produce secretions • Onto epithelial surfaces • Through ducts © 2012 Pearson Education, Inc. Glandular Epithelia o Modes of Secretion 1. Merocrine secretion 2. Apocrine secretion 3. Holocrine secretion © 2012 Pearson Education, Inc. o Merocrine Secretion • Produced in Golgi apparatus • Released by vesicles (exocytosis) • For example, sweat glands o Apocrine Secretion • Produced in Golgi apparatus • Released by shedding cytoplasm • For example, mammary glands o Holocrine Secretion • Released by cells bursting, killing gland cells • Gland cells replaced by stem cells • For example, sebaceous glands Secretory vesicle Golgi apparatus Nucleus TEM 3039 Salivary gland Mammary gland Breaks down Golgi apparatus Secretion Regrowth Hair Sebaceous gland Cells burst, releasing cytoplasmic contents Hair follicle Cells produce secretion, increasing in size Cell division replaces lost cells Stem cell Glandular Epithelia o Types of Secretions • Serous glands • Watery secretions • Mucous glands • Secrete mucins • Mixed exocrine glands • Both serous and mucous © 2012 Pearson Education, Inc. Glandular Epithelia o Gland Structure • Unicellular glands • Mucous (goblet) cells are the only unicellular exocrine glands • Scattered among epithelia • For example, in intestinal lining © 2012 Pearson Education, Inc. Gland Structure • Multicellular glands 1. Structure of the duct • Simple (undivided) • Compound (divided) 2. Shape of secretory portion of the gland • Tubular (tube shaped) • Alveolar or acinar (blind pockets) 3. Relationship between ducts and glandular areas • Branched (several secretory areas sharing one duct) © 2012 Pearson Education, Inc. SIMPLE GLANDS Duct Gland cells SIMPLE TUBULAR Examples: • Intestinal glands SIMPLE COILED TUBULAR Examples: • Merocrine sweat glands SIMPLE ALVEOLAR (ACINAR) Examples: • Not found in adult; a stage in development of simple branched glands SIMPLE BRANCHED TUBULAR Examples: • Gastric glands • Mucous glands of esophagus, tongue, duodenum SIMPLE BRANCHED ALVEOLAR Examples: • Sebaceous (oil) glands COMPOUND GLANDS COMPOUND TUBULAR Examples: • Mucous glands (in mouth) • Bulbo-urethral glands (in male reproductive system) • Testes (seminiferous tubules) COMPOUND ALVEOLAR (ACINAR) Examples: • Mammary glands COMPOUND TUBULOALVEOLAR Examples: • Salivary glands • Glands of respiratory passages • Pancreas Characteristics of Connective Tissue 1. Specialized cells 2. Solid extracellular protein fibers 3. Fluid extracellular ground substance The Extracellular Components of Connective Tissue (Fibers and Ground Substance) o Make up the matrix • Majority of tissue volume • Determines specialized function © 2012 Pearson Education, Inc. Functions of Connective Tissue o Establishing a structural framework for the body o Transporting fluids and dissolved materials o Protecting delicate organs o Supporting, surrounding, and interconnecting other types of tissue o Storing energy reserves, especially in the form of triglycerides o Defending the body from invading microorganisms © 2012 Pearson Education, Inc. Classification of Connective Tissues 1. Connective tissue proper • Connect and protect 2. Fluid connective tissues • Transport 3. Supporting connective tissues • Structural strength © 2012 Pearson Education, Inc. Categories of Connective Tissue Proper o Loose connective tissue • More ground substance, fewer fibers • For example, fat (adipose tissue) o Dense connective tissue • More fibers, less ground substance • For example, tendons © 2012 Pearson Education, Inc. Connective Tissue Proper Cell Populations Fibroblasts Mast cells Fibrocytes Lymphocytes Adipocytes Microphages Mesenchymal cells Melanocytes Macrophages © 2012 Pearson Education, Inc. Fibroblasts o The most abundant cell type • Found in all connective tissue proper • Secrete proteins and hyaluronan (cellular cement) Fibrocytes o The second most abundant cell type • Found in all connective tissue proper • Maintain the fibers of connective tissue proper © 2012 Pearson Education, Inc. Adipocytes o Fat cells • Each cell stores a single, large fat droplet Mesenchymal Cells o Stem cells that respond to injury or infection • Differentiate into fibroblasts, macrophages, etc. © 2012 Pearson Education, Inc. Macrophages o Large, amoeba-like cells of the immune system • Eat pathogens and damaged cells • Fixed macrophages stay in tissue • Free macrophages migrate © 2012 Pearson Education, Inc. Mast Cells o Stimulate inflammation after injury or infection • Release histamine and heparin o Basophils are leukocytes (white blood cells) that also contain histamine and heparin © 2012 Pearson Education, Inc. Lymphocytes o Specialized immune cells in lymphatic (lymphoid) system • For example, lymphocytes may develop into plasma cells (plasmocytes) that produce antibodies © 2012 Pearson Education, Inc. Microphages o Phagocytic blood cells • Respond to signals from macrophages and mast cells • For example, neutrophils and eosinophils Melanocytes o Synthesize and store the brown pigment melanin © 2012 Pearson Education, Inc. Connective Tissue Fibers 1. Collagen fibers 2. Reticular fibers 3. Elastic fibers © 2012 Pearson Education, Inc. Collagen Fibers o Most common fibers in connective tissue proper o Long, straight, and unbranched o Strong and flexible o Resist force in one direction o For example, tendons and ligaments Reticular Fibers o Network of interwoven fibers (stroma) o Strong and flexible o Resist force in many directions o Stabilize functional cells (parenchyma) and structures o For example, sheaths around organs © 2012 Pearson Education, Inc. Elastic Fibers o Contain elastin o Branched and wavy o Return to original length after stretching o For example, elastic ligaments of vertebrae © 2012 Pearson Education, Inc. Ground Substance o Is clear, colorless, and viscous o Fills spaces between cells and slows pathogen movement © 2012 Pearson Education, Inc. Reticular fibers Melanocyte Fixed macrophage Plasma cell Mast cell Elastic fibers Free macrophage Collagen fibers Blood in vessel Fibroblast Adipocytes (fat cells) Mesenchymal cell Ground substance Lymphocyte Elastic fibers Collagen fibers Fibroblast Free macrophage Connective tissue proper LM 502 Embryonic Connective Tissues o Are not found in adults o Mesenchyme (embryonic stem cells) • The first connective tissue in embryos o Mucous connective tissue • Loose embryonic connective tissue © 2012 Pearson Education, Inc. Mesenchymal cells Mesenchyme LM 136 This is the first connective tissue to appear in an embryo. Mesenchymal cells Blood vessel Mucous connective tissue (Wharton’s jelly) LM 136 This sample was taken from the umbilical cord of a fetus. Loose Connective Tissues o The “packing materials” of the body o Three types in adults 1. Areolar 2. Adipose 3. Reticular © 2012 Pearson Education, Inc. Areolar Tissue o Least specialized o Open framework o Viscous ground substance o Elastic fibers o Holds blood vessels and capillary beds • For example, under skin (subcutaneous layer) © 2012 Pearson Education, Inc. Adipose Tissue o Contains many adipocytes (fat cells) o 2 types of adipose tissue 1. White fat 2. Brown fat © 2012 Pearson Education, Inc. White fat o Most common o Stores fat o Absorbs shocks o Slows heat loss (insulation) Brown fat o More vascularized o Adipocytes have many mitochondria o When stimulated by nervous system, fat breakdown accelerates, releasing energy o Absorbs energy from surrounding tissues © 2012 Pearson Education, Inc. Adipose Tissue o Adipose cells • Adipocytes in adults do not divide • Expand to store fat • Shrink as fats are released • Mesenchymal cells divide and differentiate • To produce more fat cells • When more storage is needed © 2012 Pearson Education, Inc. Reticular Tissue o Provides support o Complex, three-dimensional network o Supportive fibers (stroma) • Support functional cells (parenchyma) o Reticular organs • Spleen, liver, lymph nodes, and bone marrow © 2012 Pearson Education, Inc. Adipose Tissue LOCATIONS: Deep to the skin, especially at sides, buttocks, breasts; padding around eyes and kidneys FUNCTIONS: Provides padding and cushions shocks; insulates (reduces heat loss); stores energy Adipocytes (white adipose cells) Adipose tissue LM 300 Reticular Tissue LOCATIONS: Liver, kidney, spleen, lymph nodes, and bone marrow FUNCTIONS: Provides supporting framework Reticular fibers Reticular tissue from liver Reticular Tissue LM 375 Dense Connective Tissues o Connective tissues proper, tightly packed with high numbers of collagen or elastic fibers • Dense regular connective tissue • Dense irregular connective tissue • Elastic tissue © 2012 Pearson Education, Inc. Dense Regular Connective Tissue o Tightly packed, parallel collagen fibers • Tendons attach muscles to bones • Ligaments connect bone to bone and stabilize organs • Aponeuroses attach in sheets to large, flat muscles © 2012 Pearson Education, Inc. Dense Regular Connective Tissue LOCATIONS: Between skeletal muscles and skeleton (tendons and aponeuroses); between bones or stabilizing positions of internal organs (ligaments); covering skeletal muscles; deep fasciae FUNCTIONS: Provides firm attachment; conducts pull of muscles; reduces friction between muscles; stabilizes relative positions of bones Collagen fibers Fibroblast nuclei Tendon LM 440 Dense Irregular Connective Tissue o Interwoven networks of collagen fibers • Layered in skin • Around cartilages (perichondrium) • Around bones (periosteum) • Form capsules around some organs (e.g., liver, kidneys) © 2012 Pearson Education, Inc. Dense Irregular Connective Tissue LOCATIONS: Capsules of visceral organs; periostea and perichondria; nerve and muscle sheaths; dermis FUNCTIONS: Provides strength to resist forces applied from many directions; helps prevent overexpansion of organs such as the urinary bladder Collagen fiber bundles Deep dermis LM 111 Elastic Tissue o Made of elastic fibers • For example, elastic ligaments of spinal vertebrae © 2012 Pearson Education, Inc. Elastic Tissue LOCATIONS: Between vertebrae of the spinal column (ligamentum flavum and ligamentum nuchae); ligaments supporting penis; ligaments supporting transitional epithelia; in blood vessel walls Elastic fibers FUNCTIONS: Stabilizes positions of vertebrae and penis; cushions shocks; permits expansion and contraction of organs Fibroblast nuclei Elastic ligament LM 887 Fluid Connective Tissues o Blood and lymph o Watery matrix of dissolved proteins o Carry specific cell types (formed elements) • Formed elements of blood • Red blood cells (erythrocytes) • White blood cells (leukocytes) • Platelets © 2012 Pearson Education, Inc. Fluid Elements of Connective Tissues o Extracellular • Plasma • Interstitial fluid • Lymph © 2012 Pearson Education, Inc. Red blood cells Red blood cells, or erythrocytes (e-RITH-ro-sıts), are ¯ ¯ responsible for the transport of oxygen (and, to a lesser degree, of carbon dioxide) in the blood. Red blood cells account for roughly half the volume of whole blood and give blood its color. White blood cells White blood cells, or leukocytes ¯ ¯ (LOO-ko-sıts; leuko-, white), help defend the body from infection and disease. Neutrophil Eosinophil Monocytes are phagocytes similar to the free macrophages in other tissues. Lymphocytes are uncommon in the blood but they are the dominant cell type in lymph, the second type of fluid connective tissue. Basophil Eosinophils and neutrophils are phagocytes. Basophils promote inflammation much like mast cells in other connective tissues. Platelets Platelets are membrane-enclosed packets of cytoplasm that function in blood clotting. These cell fragments are involved in the clotting response that seals leaks in damaged or broken blood vessels. Lymph o Extracellular fluid • Collected from interstitial space • Monitored by immune system • Transported by lymphatic (lymphoid) system • Returned to venous system © 2012 Pearson Education, Inc. Fluid Tissue Transport Systems o Cardiovascular system (blood) • Arteries • Capillaries • Veins o Lymphatic (lymphoid) system (lymph) • Lymphatic vessels © 2012 Pearson Education, Inc. Support Soft Tissues and Body Weight o Cartilage • Gel-type ground substance • For shock absorption and protection o Bone • Calcified (made rigid by calcium salts, minerals) • For weight support © 2012 Pearson Education, Inc. Cartilage Matrix o Proteoglycans derived from chondroitin sulfates o Ground substance proteins Chondrocytes (cartilage cells) surrounded by lacunae (chambers) © 2012 Pearson Education, Inc. Cartilage Structure o No blood vessels • Chondrocytes produce antiangiogenesis factor o Perichondrium • Outer, fibrous layer (for strength) • Inner, cellular layer (for growth and maintenance) © 2012 Pearson Education, Inc. Matrix New matrix Chondrocyte Lacuna Chondrocyte undergoes division within a lacuna surrounded by cartilage matrix. Interstitial growth As daughter cells secrete additional matrix, they move apart, expanding the cartilage from within. Dividing stem cell Fibroblast Perichondrium New matrix Chondroblasts Immature chondrocyte Older matrix Cells in the cellular layer of the perichondrium differentiate into chondroblasts. Appositional growth These immature chondroblasts secrete new matrix. Mature chondrocyte As the matrix enlarges, more chondroblasts are incorporated; they are replaced by divisions of stem cells in the perichondrium. Types of Cartilage 1. Hyaline cartilage 2. Elastic cartilage 3. Fibrocartilage (fibrous cartilage) © 2012 Pearson Education, Inc. Hyaline Cartilage o Stiff, flexible support o Reduces friction between bones o Found in synovial joints, rib tips, sternum, and trachea Elastic Cartilage o Supportive but bends easily o Found in external ear and epiglottis © 2012 Pearson Education, Inc. Fibrocartilage (Fibrous Cartilage) o Limits movement o Prevents bone-to-bone contact o Pads knee joints o Found between pubic bones and intervertebral discs © 2012 Pearson Education, Inc. Hyaline Cartilage LOCATIONS: Between tips of ribs and bones of sternum; covering bone surfaces at synovial joints; supporting larynx (voice box), trachea, and bronchi; forming part of nasal septum FUNCTIONS: Provides stiff but somewhat flexible support; reduces friction between bony surfaces Chondrocytes in lacunae Matrix LM 500 Hyaline cartilage Elastic Cartilage LOCATIONS: Auricle of external ear; epiglottis; auditory canal; cuneiform cartilages of larynx FUNCTIONS: Provides support, but tolerates distortion without damage and returns to original shape Chondrocyte in lacuna Elastic fibers in matrix LM 358 Elastic cartilage Fibrocartilage LOCATIONS: Pads within knee joint; between pubic bones of pelvis; intervertebral discs FUNCTIONS: Resists compression; prevents boneto-bone contact; limits movement Chondrocytes in lacunae Fibrous matrix LM 400 Fibrocartilage Bone or Osseous Tissue o Strong (calcified calcium salt deposits) o Resists shattering (flexible collagen fibers) Bone Cells or Osteocytes o Arranged around central canals within matrix o Small channels through matrix (canaliculi) access blood supply Periosteum o Covers bone surfaces o Fibrous layer o Cellular layer © 2012 Pearson Education, Inc. Canaliculi Osteocytes in lacunae Matrix Osteon Central canal Blood vessels Osteon LM 375 Fibrous layer Cellular layer Periosteum Membranes o Physical barriers o Line or cover portions of the body o Consist of: • An epithelium • Supported by connective tissue © 2012 Pearson Education, Inc. Four Types of Membranes 1. Mucous membranes 2. Serous membranes 3. Cutaneous membrane 4. Synovial membranes © 2012 Pearson Education, Inc. Mucous Membranes (Mucosae) o Line passageways that have external connections o In digestive, respiratory, urinary, and reproductive tracts o Epithelial surfaces must be moist • To reduce friction • To facilitate absorption and excretion o Lamina propria • Is areolar tissue © 2012 Pearson Education, Inc. Mucous secretion Epithelium Lamina propria (areolar tissue) Mucous membranes are coated with the secretions of mucous glands. These membranes line the digestive, respiratory, urinary, and reproductive tracts. Serous Membranes o Line cavities not open to the outside o Are thin but strong o Have fluid transudate to reduce friction o Have a parietal portion covering the cavity o Have a visceral portion (serosa) covering the organs © 2012 Pearson Education, Inc. Three Serous Membranes 1. Pleura • Lines pleural cavities • Covers lungs 2. Peritoneum • Lines peritoneal cavity • Covers abdominal organs 3. Pericardium • Lines pericardial cavity • Covers heart © 2012 Pearson Education, Inc. Cutaneous Membrane o Is skin, surface of the body o Thick, waterproof, and dry Synovial Membranes o Line moving, articulating joint cavities o Produce synovial fluid (lubricant) o Protect the ends of bones o Lack a true epithelium © 2012 Pearson Education, Inc. Epithelium Areolar tissue Dense irregular connective tissue The cutaneous membrane, or skin, covers the outer surface of the body. Articular (hyaline) tissue Synovial fluid Capsule Capillary Adipocytes Areolar tissue Epithelium Synovial membrane Bone Synovial membranes line joint cavities and produce the fluid within the joint. Connective Tissues 1. Provide strength and stability 2. Maintain positions of internal organs 3. Provide routes for blood vessels, lymphatic vessels, and nerves Fasciae o Singular form = fascia • The body’s framework of connective tissue • Layers and wrappings that support or surround organs © 2012 Pearson Education, Inc. Three Types of Fasciae 1. Superficial fascia 2. Deep fascia 3. Subserous fascia © 2012 Pearson Education, Inc. Body wall Connective Tissue Framework of Body Body cavity Superficial Fascia • Between skin and underlying organs • Areolar tissue and adipose tissue • Also known as subcutaneous layer or hypodermis Skin Deep Fascia • Forms a strong, fibrous internal framework • Dense connective tissue • Bound to capsules, tendons, and ligaments Subserous Fascia Rib • Between serous membranes and deep fascia • Areolar tissue Serous membrane Cutaneous membrane Muscle Tissue o Specialized for contraction o Produces all body movement o Three types of muscle tissue 1. Skeletal muscle tissue • Large body muscles responsible for movement 2. Cardiac muscle tissue • Found only in the heart 3. Smooth muscle tissue • Found in walls of hollow, contracting organs (blood vessels; urinary bladder; respiratory, digestive, and reproductive tracts) © 2012 Pearson Education, Inc. Classification of Muscle Cells o Striated (muscle cells with a banded appearance) o Nonstriated (not banded; smooth) o Muscle cells can have a single nucleus o Muscle cells can be multinucleate o Muscle cells can be controlled voluntarily (consciously) o Muscle cells can be controlled involuntarily (automatically) © 2012 Pearson Education, Inc. Skeletal Muscle Cells o Long and thin o Usually called muscle fibers o Do not divide o New fibers are produced by stem cells (myosatellite cells) © 2012 Pearson Education, Inc. Skeletal Muscle Tissue Cells are long, cylindrical, striated, and multinucleate. Nuclei LOCATIONS: Combined with connective tissues and neural tissue in skeletal muscles FUNCTIONS: Moves or stabilizes the position of the skeleton; guards entrances and exits to the digestive, respiratory, and urinary tracts; generates heat; protects internal organs Muscle fiber Striations Skeletal muscle LM 180 Cardiac Muscle Cells o Called cardiocytes o Form branching networks connected at intercalated discs o Regulated by pacemaker cells Smooth Muscle Cells o Small and tapered o Can divide and regenerate © 2012 Pearson Education, Inc. Cardiac Muscle Tissue Nucleus Cells are short, branched, and striated, usually with a single nucleus; cells are interconnected by intercalated discs. Cardiac muscle cells LOCATION: Heart FUNCTIONS: Circulates blood; maintains blood (hydrostatic) pressure Intercalated discs Striations Cardiac muscle LM 450 Smooth Muscle Tissue Cells are short, spindle-shaped, and nonstriated, with a single, central nucleus. LOCATIONS: Found in the walls of blood vessels and in digestive, respiratory, urinary, and reproductive organs Nucleus FUNCTIONS: Moves food, urine, and reproductive tract secretions; controls diameter of respiratory passageways; regulates diameter of blood vessels Smooth muscle cell Smooth muscle LM 235 Neural Tissue o Also called nervous or nerve tissue • Specialized for conducting electrical impulses • Rapidly senses internal or external environment • Processes information and controls responses o Neural tissue is concentrated in the central nervous system • Brain • Spinal cord © 2012 Pearson Education, Inc. Two Types of Neural Cells 1. Neurons • Nerve cells • Perform electrical communication 2. Neuroglia • Supporting cells • Repair and supply nutrients to neurons © 2012 Pearson Education, Inc. Cell Parts of a Neuron o Cell body • Contains the nucleus and nucleolus o Dendrites • Short branches extending from the cell body • Receive incoming signals o Axon (nerve fiber) • Long, thin extension of the cell body • Carries outgoing electrical signals to their destination © 2012 Pearson Education, Inc. NEURONS NEUROGLIA (supporting cells) Nuclei of neuroglia Cell body Axon • Maintain physical structure of tissues • Repair tissue framework after injury • Perform phagocytosis • Provide nutrients to neurons • Regulate the composition of the interstitial fluid surrounding neurons Nucleolus Nucleus of neuron Dendrites LM 600 Dendrites (contacted by other neurons) Mitochondrion Nucleus Axon (conducts information to other cells) Microfibrils and microtubules Nucleolus Contact with other cells Cell body (contains nucleus and major organelles) A representative neuron (sizes and shapes vary widely) Nuclei of neuroglia Cell body Axon Nucleolus Nucleus of neuron Dendrites LM 600 NEUROGLIA (supporting cells) • Maintain physical structure of tissues • Repair tissue framework after injury • Perform phagocytosis • Provide nutrients to neurons • Regulate the composition of the interstitial fluid surrounding neurons Dendrites (contacted by other neurons) Mitochondrion Nucleus Axon (conducts information to other cells) Microfibrils and microtubules Nucleolus Cell body (contains nucleus A representative neuron and major organelles) (sizes and shapes vary widely) Contact with other cells Tissues Respond to Injuries o To maintain homeostasis • Cells restore homeostasis with two processes 1. Inflammation 2. Regeneration © 2012 Pearson Education, Inc. Inflammation = Inflammatory Response o The tissue’s first response to injury Signs and symptoms of the inflammatory response include: o Swelling o Redness o Heat o Pain © 2012 Pearson Education, Inc. Inflammatory Response o Can be triggered by: • Trauma (physical injury) • Infection (the presence of harmful pathogens) © 2012 Pearson Education, Inc. The Process of Inflammation o Damaged cells release chemical signals into the surrounding interstitial fluid • Prostaglandins • Proteins • Potassium ions © 2012 Pearson Education, Inc. The Process of Inflammation o As cells break down: • Lysosomes release enzymes that destroy the injured cell and attack surrounding tissues • Tissue destruction is called necrosis © 2012 Pearson Education, Inc. The Process of Inflammation o Necrotic tissues and cellular debris (pus) accumulate in the wound • Abscess – pus trapped in an enclosed area o Injury stimulates mast cells to release: • Histamine • Heparin • Prostaglandins © 2012 Pearson Education, Inc. The Process of Inflammation o Dilation of blood vessels • Increases blood circulation in the area • Causes warmth and redness • Brings more nutrients and oxygen to the area • Removes wastes © 2012 Pearson Education, Inc. The Process of Inflammation o Plasma diffuses into the area • Causes swelling and pain o Phagocytic white blood cells • Clean up the area © 2012 Pearson Education, Inc. Regeneration o When the injury or infection is cleaned up • Healing (regeneration) begins The Process of Regeneration o Fibrocytes move into necrotic area • Lay down collagen fibers • To bind the area together (scar tissue) © 2012 Pearson Education, Inc. The Process of Regeneration o New cells migrate into area • Or are produced by mesenchymal stem cells o Not all tissues can regenerate • Epithelia and connective tissues regenerate well • Cardiac cells and neurons do not regenerate (or regenerate poorly) © 2012 Pearson Education, Inc. Mast Cell Activation stimulates Exposure to Pathogens and Toxins Injured tissue contains an abnormal concentration of pathogens, toxins, waste products, and the chemicals from injured cells. When a tissue is injured, a general defense mechanism is activated. When an injury damages connective tissue, mast cells release a variety of chemicals. This process, called mast cell activation, stimulates inflammation. Mast cell Mast Cell Activation When an injury damages connective tissue, mast cells release a variety of chemicals. This process, called mast cell activation, stimulates inflammation. Mast cell Histamine Heparin Prostaglandins INFLAMMATION Inflammation produces several familiar indications of injury, including swelling, redness, warmth, and pain. Inflammation may also result from the presence of pathogens, such as harmful bacteria, within the tissues; the presence of these pathogens constitutes an infection. Increased Blood Flow Increased Vessel Permeability Pain In response to the released chemicals, blood vessels dilate, increasing blood flow through the damaged tissue. Vessel dilation is accompanied by an increase in the permeability of the capillary walls. Plasma now diffuses into the injured tissue, so the area becomes swollen. The abnormal conditions within the tissue and the chemicals released by mast cells stimulate nerve endings that produce the sensation of pain. PAIN Increased Local Temperature Increased Oxygen and Nutrients Increased Phagocytosis Removal of Toxins and Wastes The increased blood flow and permeability causes the tissue to become warm and red. Vessel dilation, increased blood flow, and increased vessel permeability result in enhanced delivery of oxygen and nutrients. Phagocytes in the tissue are activated, and they begin engulfing tissue debris and pathogens. Enhanced circulation carries away toxins and waste products, distributing them to the kidneys for excretion, or to the liver for inactivation. O2 Toxins and wastes Regeneration Regeneration is the repair that occurs after the damaged tissue has been stabilized and the inflammation has subsided. Fibroblasts move into the area, laying down a collagenous framework known as scar tissue. Over time, scar tissue is usually “remodeled” and gradually assumes a more normal appearance. Inflammation Subsides Over a period of hours to days, the cleanup process generally succeeds in eliminating the inflammatory stimuli. Normal tissue conditions restored Inhibits mast cell activation Regeneration Regeneration is the repair that occurs after the damaged tissue has been stabilized and the inflammation has subsided. Fibroblasts move into the area, laying down a collagenous framework known as scar tissue. Over time, scar tissue is usually “remodeled” and gradually assumes a more normal appearance. Aging and Tissue Structure o Speed and efficiency of tissue repair decrease with age, due to: • Slower rate of energy consumption (metabolism) • Hormonal alterations • Reduced physical activity © 2012 Pearson Education, Inc. Effects of Aging o Chemical and structural tissue changes • Thinning epithelia and connective tissues • Increased bruising and bone brittleness • Joint pain and broken bones • Cardiovascular disease • Mental deterioration © 2012 Pearson Education, Inc. Aging and Cancer Incidence o Cancer rates increase with age • 25% of all people in the United States develop cancer • Cancer is the #2 cause of death in the United States • Environmental chemicals and cigarette smoke cause cancer © 2012 Pearson Education, Inc. Primary germ layers: ectoderm, mesoderm, and endoderm o Three layers of cells formed early in embryonic development o Specialize to form the four primary tissues Nerve tissue arises from ectoderm © 2012 Pearson Education, Inc. Muscle, connective tissue, endothelium, and mesothelium arise from mesoderm Most mucosae arise from endoderm Epithelial tissues arise from all three germ layers © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. Figure 4.14