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Tissue Level Of Organization Introduction Epithelial Tissue Connective Tissue Muscle Tissue Nervous Tissue Cells, Tissues, & Organ Systems • To View Video: – Move mouse cursor over slide titlelink – When hand appears, click once • ASX Video plays about 31/2 min Learning Objectives • Introduction: Identify the four major tissue types of the body & their roles • Epithelial Tissue: Discuss the types & functions of epithelial cells Describe the relationship between form & function for each epithelial type • Connective Tissues: Compare the structures & functions of the various types of connective tissues Tissue Types & Functions • Epithelial Tissue Covers exposed surfaces Lines internal passages & chambers Forms glands • Connective Tissue Fills internal spaces Provides structural support for other tissues Transports materials w/in the body Stores energy reserves Tissue Types & Functions • Muscle Tissue Contracts to perform specific movements Generates heat to warm the body • Nervous Tissue Carries information from one part of the body to another in the form of electrical impulses Epithelial Tissue • • • • Characteristics Functions Specializations Epithelial Integrity Characteristics • Cellularity cell junctions • Polarity apical surface basal surface • Attachment basal membrane • Avascularity No blood vessels • Regeneration stem cell mitosis Functions • Provide physical protection Protect exposed & internal surfaces from abrasion, dehydration, & destruction by chemical or biological agents • Control of permeability Substances enter & leave body across an epithelium May be regulated by hormones Functions • Provide sensation Extensive innervation by sensory nerves Detect: touch, temperature change Neuroepithelia provide: smell, taste, sight, equilibrium, & hearing • Produce specialized secretions Gland cells Endocrine glands – secretions discharged into interstitial fluid or blood (hormones) Exocrine glands – secretions discharged onto surface of skin or other internal surface (sweat glands; digestive glands) Specializations • Production of secretions – Glandular epithelia • Movement of fluids over the epithelial surface – Ciliated epithelia • Transport of substances through the epithelium – Microvilli – increase surface area for absorption Cell Attachments Maintenance of Epithelial Integrity • Intercellular connections Tight junctions – belt-like connections Partial fusion of lipid bilayer of adjacent cells Desmosomes – bands & rivets Cytoskeletal elements link through cell membrane • Belt desmosomes – band that encircles cell • Button desmosome – fibrous discs Gap junctions – channels Interlocking membrane channel proteins Maintenance of Epithelial Integrity • Basement membrane Basal lamina – secreted by epithelial cells (closest to epithelial cells) Fine network of protein filaments & glycoproteins Provides protective barrier Reticular lamina – secreted by underlying connective tissue cells Course bundles of protein fibers Provides strength Maintenance of Epithelial Integrity • Maintenance & repair Epithelial cells exposed to mechanical abrasion, toxic chemicals, disruptive enzymes, pathogenic bacteria Germinative cells A.k.a., stem cells Located in deepest layers of an epithelium Undergo active mitosis throughout life to replace damaged or dead cells in the epithelium Epithelial Tissue Terminology: Layers • Simple 1 layer of cells all in contact w/ basement membrane • Stratified 2 or > layers of cells bottom layer in contact w/ basement membrane • Pseudostratified 1 layer of cells arrangement of nuclei gives appearance of several layers all in contact w/ basement membrane Epithelial Tissue Terminology: Cell Shapes • Squamous cells thin; flattened; irregular appear spindle-like in sectional view; appear like “fried eggs” in surface view • Cuboidal cells hexagonal; box-like appear square in sectional view • Columnar cells hexagonal; tall & slender appear rectangular in sectional view Epithelial Tissue Classification • Classification of Epithelia: Squamous epithelia Simple Stratified Cuboidal epithelia Simple Stratified Transitional (type of stratified) Columnar epithelia Simple Stratified Pseudostratified General Epithelia cell layer basement membrane underlying connective tissue Simple Squamous Epithelium • Locations mesothelial linings of body cavities endothelial lining of heart & blood vessels kidney tubules (loop of Henle) inner lining of cornea alveoli of lungs • Functions protection reduce friction control vessel permeability absorption & secretion Stratified Squamous Epithelium • Locations surface of skin lining of mouth, pharynx, esophagus, rectum, anus lining of vagina • Functions physical protection against abrasion protection from pathogen & chemical attack Simple Cuboidal Epithelium • Locations Basement exocrine glands Membrane ducts kidney tubules thyroid (endocrine) gland • Functions limited protection Lumen Nuclei of secretion &/or absorption Cells in 1 Layer Stratified Cuboidal Epithelium Basement Membrane • Locations Connective Tissue lining of some ducts (rare) • Functions protection secretion absorption Lumen Nuclei of Cells in 2 Layers Transitional Epithelium relaxed • Locations urinary bladder stretched renal pelvis ureters • Functions Basement Membrane protection permit expansion & recoil after stretching Connective Tissue Simple Columnar Epithelium • Locations lining of stomach, intestine, & gall bladder lining of uterine tubes collecting ducts of kidney • Functions protection secretion & absorption surface movement Stratified Columnar Epithelium • Locations Superficial Columnar Cells small areas of pharynx Deeper Columnar Cells epiglottis salivary gland ducts & anus mammary glands urethra • Function protection Pseudostratified Columnar Epithelium • Locations lining of nasal cavity lining of bronchi • Functions protection secretion surface movement Glandular Epithelial Tissue • Glandular Epithelia: Endocrine glands – no ducts Exocrine glands – w/ ducts Modes of secretion Types of secretions Gland structure Unicellular – goblet cell only Multicellular – all other glands • Simple • Compound Modes of Secretion • Merocrine secretion secretory vesicles released from intact cell by exocytosis; whole cell left intact • Apocrine secretion apical portion of cytoplasm packed w/ secretory vesicles is shed; part of cell destroyed • Holocrine secretion entire cell packed w/ secretory vesicles disintegrates; whole cell destroyed Types of Secretions • Mucus glands mucin – glycoprotein: becomes slippery lubricant • Serous glands watery solution w/ enzymes • Mixed mucus & serous more than 1 type of gland cell; secretes both mucus & watery solution Exocrine Gland Structure • Shape of secretory portion of gland tubular – tube-like arrangement alveolar (acinar) – pocket-like arrangement tubuloalveolar – combination of above • Branching pattern of ducts simple – undivided duct leading to gland cells compound – ducts divide leading to gland cells Exocrine Gland Structure • Relationship btw/ ducts & glandular areas branched – several secretory areas share a common duct Always refers to glandular areas not to duct Connective Tissues • Basic Structure • Functions • Classification Categories: connective tissue proper fluid connective tissues supporting connective tissues Basic Tissue Components • Specialized cell types – widely separated • Extracellular protein fibers • Ground substance (extracellular fluid) Viscosity Syrupy in most connective tissues • proteoglycans • glycoproteins Watery in fluid connective tissues Note: extracellular fibers & ground substance constitute the extracellular matrix Extracellular Matrix fluid ground substance protein fibers Functions Note examples of common connective tissues • Structural framework • Transport of fluids & dissolved materials • Protection/insulation of delicate organs • Support & interconnection of other tissue types • Storage of energy reserves • Defense against microorganisms Examples of Common Connective Tissues Note functions • Adipose (fat) tissue – protection; insulation, & energy storage • Tendons & ligaments – support & anatomical interconnection • Fascia – framework & anatomical interconnection Examples of Common Connective Tissues • Blood & lymph – transport (physiological interconnection) & defense • Cartilage & bone – support, anatomical interconnection & protection Connective Tissue Categories • Connective tissue proper Loose connective tissue Dense connective tissue • Fluid connective tissues Blood Lymph • Supporting connective tissue Cartilage Bone Connective Tissue Proper: Classification • Connective Tissue Proper cell populations fibers types ground substance Connective Tissue Proper: Cell Types • Fibroblasts – make fibers • Macrophages – engulf pathogens & dead cells • Adipocytes – store lipid triglycerides • Mesenchymal cells – stem cells: differentiate into different cell types when needed Connective Tissue Proper: Cell Types • Melanocytes – pigment cells • Mast cells – wound-healing response • Lymphocytes – killer cells & antibodies • Microphages (eosinophils & neutrophils from plasma) – engulf pathogens; produce chemicals important in responses to wounds Connective Tissue Proper: Fiber Types • Collagen fibers protein: collagen long; thick; straight; unbranched skin; bone; tendons & ligaments most common fiber in body • Reticular fibers collagen-like protein short; thin; branched stabilize organs Connective Tissue Proper: Fiber Types • Elastic fibers protein: elastin long; thin; wavy; branched elastic ligaments of vertebrae Connective Tissue Proper: Ground Substance • Characteristics Clear Colorless Viscous Syrupy in most connective tissues • proteoglycans • glycoproteins Connective Tissue Proper: Characteristics • Loose Connective Tissues Areolar tissue Specialized loose connective tissues Adipose tissue Reticular tissue Loose Connective Tissue: Areolar • Locations Wide-spread “packing material” of the body Fills spaces btw/ organs Supports epithelia Surrounds blood vessels & nerves • Functions Provides cushioning Provides routes for diffusion of nutrients btw/ other tissues Specialized varieties: adipose tiss. & reticular tiss. Loose Connective Tissue: Adipose Tissue • Locations Under skin Breasts, buttocks, groin Eye sockets Surrounds kidneys & heart Fat “apron” covers abdominal cavity • Functions Body contouring associated w/ sexual attraction Padding against mechanical shock Insulation – preventing heat loss Packing around delicate structures Loose Connective Tissue: Reticular Tissue Spleen, liver Lymph nodes, bone marrow • Functions Structural framework of body organs Reticular Fibers • Locations Connective Tissue Proper: Characteristics • Dense Connective Tissues Regular dense connective tissue Elastic tissue Irregular dense connective tissue • Locations collagen fibers Dense Connective Tissue: Regular • Functions provide firm attachment conducts pull of muscles reduce friction betw/ muscles stabilizes position of bones fibroblast nuclei tendons - betw/ skeletal muscles & skeleton ligaments – betw/ bones covering skeletal muscles (deep fascia) vertebral ligaments under transitional epithelium walls of blood vessels walls of respiratory passages • Functions stabilizes position of vertebrae allows cycles of expansion & contraction fibroblast nuclei • Locations elastin fibers Dense Regular Connective Tissue: Elastic Dense Connective Tissue: Irregular • Locations collagen capsules of visceral organs fiber periostea & perichondria (membranes bundles around bones & cartilage) nerve & muscle sheaths dermis • Functions provide strength to resist multidirectional forces prevents over-expansion of organs (e.g., urinary bladder) Fluid Connective Tissue • Blood formed elements plasma proteins plasma • Lymph white blood cells lymph interstitial fluid Fluid Connective Tissue • Blood Cell Types: formed elements red blood cells (RBCs) white blood cells (WBCs) platelets (cell fragments) Extracellular Proteins – plasma proteins Ground Substance – plasma Blood: Formed Elements Transport O2 & CO2 Defense against disease Blood clotting Fluid Connective Tissue • Lymph Cell Types: lymphocytes – WBCs (99%) macrophages microphages Ground Substance: interstitial fluid lymph Supporting Connective Tissue • Types of Cartilage hyaline cartilage elastic cartilage fibrocartilage • Bone osseus tissue Supporting Connective Tissue • Cartilage Cell Types – chondrocytes Matrix – collagen & elastin fibers embedded in chondroitin sulfates • Bone Cell Types – osteocytes Matrix – collagen fibers embedded in calcium salts btw/ tips of ribs & sternum covering bone surfaces of synovial joints supporting larynx, trachea, & bronchi nasal septum • Functions stiff – flexible support reduces friction matrix • Locations chondrocytes Hyaline Cartilage • Locations tip of nose pinna of external ear epiglottis • Functions chondrocytes in lacunae Elastic Cartilage matrix support elastic tolerates distortion w/out damage fibers pads w/in knee joint btw/ pubic bones of pelvis intervertebral discs • Functions resists compression prevents bone-to-bone contact limits relative movement chondrocyte in lacunae • Locations collagen fibers Fibrocartilage Bone canaliculi • Locations central canal of osteon organs of the skeletal system • Functions support of the body protection of other organs movement mineral storage blood formation matrix osteocyte in lacuna Differences btw Cartilage & Bone Cartilage Vol of ground subst – greater Ground subst – firm gel Avascular – no blood Bone vessels w/in tissue Vol of ground subst – very little Ground subst – mineralized Vascular ized – blood vessels w/in tissue Learning Objectives • Membranes: Explain how epithelial membranes & connective tissues combine to form four different types of membranes Specify the functions of the various types of membranes in the body • Connective Tissue Framework: Describe how connective tissue establishes the framework of the body Membranes • Functions • Classification: Mucous membranes Serous membranes Cutaneous membrane Synovial membranes Membrane Structure & Functions • General Structure: derived from – epithelia loose connective tissue • General Functions: cover & protect organ surfaces & body cavities reduce friction due to organ & body movements absorption & secretion Mucus Membranes Structure – simple epithelium underlain by loose c.t. (lamina propria) Characteristics – thin to thick; moist; often ciliated or w/ microvilli Locus – line digestive, respiratory, urinary, & reproductive tracts Functions – protection from microorganisms, etc; absorption/secretion; surface transport Serous Membranes Structure – simple squamous mesothelium supported by loose c.t. Characteristics – thin; moist; permeable to fluids Locus – line ventral body cavity (peritoneum) & pleural & pericardial cavities Function – minimize friction btw/ internal organs Cutaneous Membrane Structure – stratified squamous epithelium underlain by loose c.t. & supported by dense c.t. Characteristics – thick, waterproof, dry Locus – outer surface of the skin Functions – protection; secretion of waste; temperature regulation, etc Synovial Membranes Structure – incomplete simple squamous or cuboidal layer supported by loose c.t. Characteristics – medium thick; highly fibrous; synovial fluid Locus – joint cavities of freely moveable joints Functions – minimize friction; prevent direct bone-bone contact Membrane Structure Connective Tissue Framework • Functions • Classification: superficial fascia deep fascia subserous fascia Fascia Structure & Functions • General Structure: membranes • General Functions: provide strength & stability maintain relative positions of internal organs provide route for distribution of blood vessels, lymphatics, & nerves Superficial Fascia Hypodermis or subcutaneous layer Locus – betw/ skin & underlying organs Structure – loose connective tissue Functions – insulation & padding; allows skin to move independently of underlying organs Deep Fascia Locus – surrounds internal organs (liver, kidneys, etc), bones (including ligaments), muscles (including tendons) Structure – dense connective tissue Functions – binding structural elements together (i.e., muscles to bones, bones to each other) Subserous Fascia Locus – betw/ deep fascia & serous membranes of the body cavities Structure – loose connective tissue Functions – prevents distortion of body cavity by movements of skeletal muscles or internal organs Learning Objectives • Muscle Tissue: Describe the three types of muscle tissue & the special structural features of each type Discuss the functions of the three types of muscle tissue • Neural Tissue: Discuss the basic structure & role of neural tissue Muscle Tissue • Functions • Classification: skeletal muscle tissue cardiac muscle tissue smooth muscle tissue Skeletal Muscle Structure & Functions • Cellular Structure: multinucleate cells long, thin “fibers” striated – due to overlapping arrangement of contractile, microfilament proteins • Functions: gross movement of the body voluntary control Skeletal Muscle Cell Structure Cardiac Muscle Structure & Functions • Cellular Structure: single nucleate cells branched w/ intercalated discs joining cells striated – overlap arrangement of contractile, microfilament proteins • Functions: pumping blood through the cardiovascular system involuntary control Cardiac Muscle Tissue Smooth Muscle Structure & Functions • Cellular Structure: single nucleate cells spindle-shaped unstriated – due to more random arrangement of contractile proteins • Functions: regulation of blood flow through vessels; movement of food through digestive system; regulation of respiratory passage diameter, etc involuntary control Smooth Muscle Cells Neural Tissue • Functions • Classification: neurons neuroglia Neurons • Cellular Structure: variable typical: tree like dendrites; soma w/ nucleus & most organelles; long, thin axon (nerve fiber) • Functions: conscious & unconscious communication by propagation of electrical impulses Neuron Structure Impulse Transmission: dendrites soma axon soma axon dendrites Neuroglia • Cellular Structure: several types of neuroglia cells: 4 major types in CNS; 2 major types in PNS • Functions: support maintain physical structure of nervous tissue repair tissue framework after injury perform phagocytosis of dead cells & microorganisms provide nutrition to neurons Neuron & Neuroglial Cells neuron neuroglial cells