4 The Tissue Level of Organization C h a p t e r PowerPoint® Lecture Slides prepared by Jason LaPres Lone Star College - North Harris

Four Types of Tissues Tissues are collections of cells and cell products that perform specific, limited functions Types of tissue Epithelial tissue Covers exposed surfaces Lines internal passageways Forms glands Copyright © 2010 Pearson Education, Inc.

Four Types of Tissues Types of Tissue (cont’d) Connective tissue Fills internal spaces Supports other tissues Transports materials Stores energy Muscle tissue Specialized for contraction Skeletal muscle, heart muscle, and walls of hollow organs Neural tissue Carries electrical signals from one part of the body to another Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Epithelia Glands Layers of cells covering internal or external surfaces Glands Structures that produce secretions Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Characteristics of Epithelia Cellularity (cell junctions) Polarity (apical and basal surfaces) Attachment (basal lamina) Avascularity Regeneration Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Figure 4–1 The Polarity of Epithelial Cells. Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Functions of Epithelial Tissue Provide physical protection Control permeability Provide sensation Produce specialized secretions (glandular epithelium) Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Specializations of Epithelial Cells Move fluids over the epithelium (protection) Move fluids through the epithelium (permeability) Produce secretions (protection and messengers) Free Surface and Attached Surface Polarity Apical surfaces: microvilli increase absorption or secretion cilia (ciliated epithelium) move fluid Basolateral surfaces Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Maintaining the Integrity of Epithelia Intercellular connections Attachment to basal lamina Epithelial maintenance and repair Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Intercellular Connections Support and communication CAMs (cell adhesion molecules): transmembrane proteins Intercellular cement: proteoglycans Hyaluronan (hyaluronic acid): glycosaminoglycans Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Intercellular Connections Cell junctions Form bonds with other cells or extracellular material: occluding (tight) junctions gap junctions macula adherens (desmosomes) Intercellular Connections Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Cell Junctions Occluding (Tight) junctions—between two plasma membranes Adhesion belt attaches to terminal web Prevents passage of water and solutes Isolates wastes in the lumen Gap junctions—allow rapid communication Held together by channel proteins (junctional proteins, connexons) Allow ions to pass Coordinate contractions in heart muscle Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Cell Junctions Macula adherens (Desmosomes) CAMs, dense areas, and intercellular cement Spot desmosomes tie cells together allow bending and twisting Hemidesmosomes attach cells to the basal lamina Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Attachment to the Basal Lamina Clear layer (Lamina lucida) Thin layer Secreted by epithelia Barrier to proteins Dense layer (Lamina densa) Thick fibers Produced by connective tissue Strength and filtration Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Figure 4–2 Intercellular Connections Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Figure 4–2 Intercellular Connections Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Figure 4–2 Intercellular Connections Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Figure 4–2 Intercellular Connections Copyright © 2010 Pearson Education, Inc.

Epithelial Tissues Epithelial Maintenance and Repair Epithelia are replaced by division of germinative cells (stem cells) Near basal lamina Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Singular epithelium; plural epithelia Classes of Epithelia 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 Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Squamous Epithelia Simple squamous epithelium Absorption and diffusion Mesothelium Lines body cavities Endothelium Lines heart and blood vessels Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–3 Squamous Epithelia. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Squamous Epithelia Stratified squamous epithelium Protects against attacks Keratin protein adds strength and water resistance Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–3 Squamous Epithelia. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Cuboidal Epithelia Simple cuboidal epithelium Secretion and absorption Stratified cuboidal epithelia Sweat ducts and mammary ducts Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–4 Cuboidal Epithelia. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–4 Cuboidal Epithelia. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Transitional Epithelium Tolerates repeated cycles of stretching and recoiling and returns to its previous shape without damage Appearance changes as stretching occurs Situated in regions of the urinary system (e.g. urinary bladder) Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–4 Cuboidal Epithelia. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Columnar Epithelia Simple columnar epithelium Absorption and secretion Pseudostratified columnar epithelium Cilia movement Stratified columnar epithelium Protection Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–5 Columnar Epithelia. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–5 Columnar Epithelia. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–5 Columnar Epithelia. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Glandular Epithelia Endocrine glands Release hormones: into interstitial fluid no ducts Exocrine glands Produce secretions: onto epithelial surfaces through ducts Mechanisms of Glandular Secretion Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Modes of Secretion in Glandular Epithelia Merocrine secretion Is produced in Golgi apparatus Is released by vesicles (exocytosis) For example, sweat glands Apocrine secretion Is released by shedding cytoplasm For example, mammary gland Holocrine secretion Is released by cells bursting, killing gland cells Gland cells replaced by stem cells For example, sebaceous gland Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–6 Modes of Glandular Secretion. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–6a Modes of Glandular Secretion. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–6b Modes of Glandular Secretion. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–6 Modes of Glandular Secretion. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Glandular Epithelia Types of secretions Serous glands: watery secretions Mucous glands: secrete mucins Mixed exocrine glands: both serous and mucous Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Glandular Epithelia Gland structure Unicellular glands Mucous (goblet) cells are the only unicellular exocrine glands: scattered among epithelia for example, in intestinal lining Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Glandular Epithelia Gland structure Multicellular glands: structure of the duct: simple (undivided) compound (divided) shape of secretory portion of the gland: tubular (tube shaped) alveolar or acinar (blind pockets) relationship between ducts and glandular areas: branched (several secretory areas sharing one duct) Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–7 A Structural Classification of Exocrine Glands. Copyright © 2010 Pearson Education, Inc.

Classification of Epithelia Figure 4–7 A Structural Classification of Exocrine Glands. Copyright © 2010 Pearson Education, Inc.

Connective Tissues Connect epithelium to the rest of the body (basal lamina) Provide structure (bone) Store energy (fat) Transport materials (blood) Have no contact with environment Copyright © 2010 Pearson Education, Inc.

Connective Tissues Characteristics of Connective Tissues Specialized cells Solid extracellular protein fibers Fluid extracellular ground substance The extracellular components of connective tissues (fibers and ground substance) make up the matrix Majority of tissue volume Determines specialized function Copyright © 2010 Pearson Education, Inc.

Connective Tissues Classification of Connective Tissues Connective tissue proper Connect and protect Fluid connective tissues Transport Supportive connective tissues Structural strength Copyright © 2010 Pearson Education, Inc.

Connective Tissues Categories of Connective Tissue Proper Loose connective tissue More ground substance, less fibers For example, fat (adipose tissue) Dense connective tissue More fibers, less ground substance For example, tendons Copyright © 2010 Pearson Education, Inc.

Connective Tissues Nine Cell Types of Connective Tissue Proper Fibroblasts Fibrocytes Macrophages Adipocytes Mesenchymal cells Melanocytes Mast cells Lymphocytes Microphages Copyright © 2010 Pearson Education, Inc.

Connective Tissues Connective Tissue Proper Cells Fibroblasts The most abundant cell type: found in all connective tissue proper secrete proteins and hyaluronan (cellular cement) Fibrocytes The second most abundant cell type: maintain the fibers of connective tissue proper Copyright © 2010 Pearson Education, Inc.

Connective Tissues Connective Tissue Proper Cells Macrophages Large, amoeba-like cells of the immune system: eat pathogens and damaged cells fixed macrophages stay in tissue free macrophages migrate Adipocytes Fat cells: each cell stores a single, large fat droplet Mesenchymal Cells Stem cells that respond to injury or infection: differentiate into fibroblasts, macrophages, etc. Copyright © 2010 Pearson Education, Inc.

Connective Tissues Connective Tissue Proper Cells Melanocytes Synthesize and store the brown pigment melanin Mast Cells Stimulate inflammation after injury or infection: release histamine and heparin Basophils are leukocytes (white blood cells) that also contain histamine and heparin Copyright © 2010 Pearson Education, Inc.

Connective Tissues Connective Tissue Proper Cells Lymphocytes Specialized immune cells in lymphoid (lymphatic) system: For example, lymphocytes may develop into plasma cells (plasmocytes) that produce antibodies Microphages Phagocytic blood cells: respond to signals from macrophages and mast cells For example, neutrophils and eosinophils Copyright © 2010 Pearson Education, Inc.

Connective Tissues Connective Tissue Fibers Collagen fibers Most common fibers in connective tissue proper Long, straight, and unbranched Strong and flexible Resist force in one direction For example, tendons and ligaments Copyright © 2010 Pearson Education, Inc.

Connective Tissues Connective Tissue Fibers Reticular fibers Network of interwoven fibers (stroma) Strong and flexible Resist force in many directions Stabilize functional cells (parenchyma) and structures For example, sheaths around organs Copyright © 2010 Pearson Education, Inc.

Connective Tissues Connective Tissue Fibers Elastic fibers Contain elastin Branched and wavy Return to original length after stretching For example, elastic ligaments of vertebrae Copyright © 2010 Pearson Education, Inc.

Connective Tissues Ground Substance Is clear, colorless, and viscous Fills spaces between cells and slows pathogen movement Copyright © 2010 Pearson Education, Inc.

Connective Tissues Figure 4–8 The Cells and Fibers of Connective Tissue Proper. Copyright © 2010 Pearson Education, Inc.

Connective Tissues Figure 4–8 The Cells and Fibers of Connective Tissue Proper. Copyright © 2010 Pearson Education, Inc.

Connective Tissues Embryonic Connective Tissues Are not found in adults Mesenchyme (embryonic stem cells) The first connective tissue in embryos Mucous connective tissue Loose embryonic connective tissue Copyright © 2010 Pearson Education, Inc.

Connective Tissues Figure 4–9 Connective Tissues in Embryos. Copyright © 2010 Pearson Education, Inc.

Connective Tissues Figure 4–9 Connective Tissues in Embryos. Copyright © 2010 Pearson Education, Inc.

Connective Tissues Loose Connective Tissues The packing materials of the body Three types in adults Areolar Adipose Reticular Copyright © 2010 Pearson Education, Inc.

Connective Tissues Areolar Tissue Least specialized Open framework Viscous ground substance Elastic fibers Holds blood vessels and capillary beds For example, under skin (subcutaneous layer) Copyright © 2010 Pearson Education, Inc.

Connective Tissues Adipose Tissue Contains many adipocytes (fat cells) Types of adipose tissue White fat: most common stores fat absorbs shocks slows heat loss (insulation) Brown fat: more vascularized adipocytes have many mitochondria when stimulated by nervous system, fat break down accelerates, releasing energy absorbs energy from surrounding tissues Copyright © 2010 Pearson Education, Inc.

Connective Tissues Adipose Tissue 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 Copyright © 2010 Pearson Education, Inc.

Connective Tissues Reticular Tissue Provides support Complex, three-dimensional network Supportive fibers (stroma) Support functional cells (parenchyma) Reticular organs Spleen, liver, lymph nodes, and bone marrow Copyright © 2010 Pearson Education, Inc.

Connective Tissues Figure 4–10 Adipose and Reticular Tissues. Copyright © 2010 Pearson Education, Inc.