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Unformatted text preview: Chapter 4: Tissue: The Living Fabric What are tissues and how are they studied? Tissue: a group of cells similar in structure that perform a similar or common function
Histology is the study of tissues Four types: Epithelial (covering) Connective (support) Muscle (movement) Nervous (control) Characteristics of Epithelia Cellularity, with little extracellular matrix Specialized contacts, with desmosomes and tight junctions Polarity, with apical and basal surfaces Basal lamina for support Microvilli and cilia may be on surface Further characteristics Supported by connective tissue, the reticular lamina + basal lamina = basement membrane Avascular, but innervated Regenerative, at high levels Types of epithelial membranes Cutaneous Mucous Serous Classification of epithelia Types of structure Simple vs. stratified Squamous Cuboidal Columnar Pseudostratified Transitional Classification of epithelia Epithelial tissues Specialized squamous epithelia Endothelium: slick, friction reducing lining of lymphatic and blood vessels Mesothelium: epithelium of serous membranes Epithelial tissues: Cuboidal Epithelial tissues: Columnar Epithelial tissues: Pseudostratified Epithelial tissues: Stratified squamous Epithelial tissues: Stratified columnar Epithelial tissues: Transitional Classes of epithelial membranes Skin Integumentary system Dry (keritanized) stratified squamous epithelial Classes of epithelial membranes Mucous Wet (moist) membranes Refers to the location, not composition Often adapted for absorption and secretion Classes of epithelial membranes Visceral and Parietal Glandular epithelia Exocrine versus endocrine glands Exocrine: duct, with local influence (secretion) Endocrine: ductless, with systemic influence (hormones) Unicellular Multicellular Generalized structure of a typical multicellular exocrine gland Types of multicellular exocrine glands Unicellular Exocrine: Produce mucin (glycoprotein) once dissolved in water, mucous, which protects and lubricates surfaces Chief modes of secretion in human exocrine glands Most are merocrine: secrete products by exocytosis Chief modes of secretion in human exocrine glands: Holocrine Holocrine: accumulate products until they rupture (ex. sebaceous) Apocrine: accumulate product, pinch off end (apex) releasing product Holocrine gland Common origin: Mesenchyme Various levels of Vascularity, from none (cartilage) to high (bone) Extracellular matrix: nonliving material Characteristics of Connective Tissue Hydroxyappetite CaPO4 (bone) Ground substances Fibers Interstitial fluid, cell adhesion proteins, proteoglycans Collagen, elastin, reticular Fundamental type (osteocyte, chondrocyte) blast: forming, clast: breakdown Cells Major classes of connective tissue Areolar connective tissue: A prototype connective Connective tissues: Loose Mesenchyme: Star shaped cells and ground substance From mesoderm Connective tissues: Loose Connective tissues: Loose Types of Adipose: White Stores nutrients and energy Brown Consumes energy to produce heat. Found in babies. Connective tissues: Loose Reticular: reticular cells forming a labyrinth or stroma Found in: Lymph nodes, Spleen, Bone Marrow Connective tissues: Dense or Fibrous Connective tissues Connective tissues Articular cartilage between bones Connective tissues Connective tissues Bone: Hard, Vascularized, Haversian canals, Lacunae Volkmann's canals Connective tissues Blood Fluid connective tissue: Has plasma and formed elements RBC's, WBC's, platelets Connective tissues Nervous tissue Neuron: nerve cell and Support cells Muscle tissues Muscle tissues Muscle tissues Steps of Tissue Repair Regeneration: replacement of destroyed tissue with the same kind Fibrosis: proliferation of fibrous connective tissue (scar tissue) Inflammation Steps for tissue repair Organization Vasoconstriction to allow clotting and inflammation to attract WBC's (produces scab) Granulation tissue allows reformation of capillary bed, macrophages reabsorb damaged tissue Fibrous reorganization matures and contracts Regeneration Tissue repair of a nonextensive skin wound: regeneration and fibrosis Tissue repair of a nonextensive skin wound: regeneration and fibrosis Tissue repair of a nonextensive skin wound: regeneration and fibrosis Embryonic germ layers and the primary tissue types they produce Embryonic development: Ectoderm: forms the outer epithelial tissues (skin) Endoderm: forms the inner epithelial tissues (digestive) Mesoderm: forms the bulk of the systems (bone, muscle) The End ...
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