Histology

Histology - BIO 201 Histology Study of Tissues Epithelial...

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Unformatted text preview: BIO 201 Histology Study of Tissues Epithelial Tissue Intercellular Junctions and Glands Connective Tissue Membranes Muscular Tissue Nervous Tissue 1 The Study of Tissues Histology (microscopic anatomy) study of tissues and how they form organs group of similar cells and cell products (i.e., ECM) composed of 2 or more tissue types (almost always connective and epithelial; usually includes muscle and nervous) epithelial ti ith li l tissue connective tissue muscular tissue nervous tissue 2 Tissue Organ Four primary tissue classes Tissues 1 BIO 201 Features of Tissues Differences between tissues type and function of cells characteristics of the surrounding matrix (extracellular (extracellular matrix; ECM) ECM) ground substance made from proteins, sugars, and sometimes minerals called many different names (ECF, ECM, tissue fluid, interstitial fluid, basement membrane) amount of space occupied by cells versus matrix very little ECM exists between epithelial and muscle cells connective tissue cells are widely separated by ECM 3 Epithelial Tissue One or more layers of closely adhering cells Forms a flat sheet with the upper surface exposed to the environment or an internal body cavity one side of tissue exposed to "outside" thin layer of collagen and adhesive proteins anchors epithelium to underlying connective tissue; provides support Sits on basement membrane (at the basal surface of cells) 4 Tissues 2 BIO 201 Layers Simple epithelium contains one layer of cells named by shape of cells Stratified epithelium contains more than one layer named by shape of apical (surface) cells deepest cells (b d t ll (b (basal cells) sit on basal cells) it l ll basement membrane 5 Shape Squamous (squashed) Allows rapid diffusion of substances; secretes serous fluid Cuboidal (square) Absorption & secretion; produces mucus Columnar (rectangular) Absorption & secretion; produces mucus Often ciliated 6 Tissues 3 BIO 201 Epithelial Functions 7 Intercellular Junctions All cells except blood cells are anchored to each other (or to the matrix surrounding them) by intercellular junctions formed by adhesion proteins 8 Tissues 4 BIO 201 Desmosomes Patch between 2 cells holding them together g g against mechanical stress CONNECTING gap between cells is spanned by mesh of filaments often called adhesion junction 9 Tight Junctions Encircle the cell joining it cell, to surrounding cells BARRIER prevents substances and bacteria from passing between cells 10 Tissues 5 BIO 201 Gap Junctions Transmembrane proteins form a water-filled channel waterSmall solutes (metabolites and ions) pass directly from cell to cell COMMUNICATING aka electrical synapse 11 Cell to Cell Junctions 12 Tissues 6 BIO 201 Endocrine and Exocrine Glands Glands secrete substances Exocrine glands connect to surface with a duct (tube) Endocrine glands secrete their products (hormones) (hormones) directly into bloodstream Some glands are mixed gonads release gametes and secrete hormones into blood pancreas secretes digestive enzymes and hormones 13 Types of Exocrine Secretions Serous glands produce thin, watery secretions sweat, milk sweat milk, tears and digestive juices Mucous glands produce a glycoprotein, mucin, mucin, that helps form a sticky secretion called mucus nasal, reproductive, respiratory secretions Cytogenic g y g glands release whole cells produce gametes 14 Tissues 7 BIO 201 Endocrine Glands Produce chemical signals that cause a response hormone Released into blood!! 15 Connective Tissue Consists of widely spaced cells separated by fibers and ground substance Most abundant and variable tissue type Functions connects structures to each other gives support and protection (physical & immune) stores energy movement and transport of materials 16 Tissues 8 BIO 201 Ground Substance of Connective Tissue Gelatinous or rubbery material found in between cells Consists of large molecules proteoglycans embedded in plasma membranes create a strong bond to other cells or extracellular matrix proteinprotein-carbohydrate complexes that bind plasma membrane to collagen or proteoglycans outside the cells glycoproteins 17 Cells of Connective Tissue Fibroblasts produce protein fibers and ground substance White blood cells Macrophages phagocytose foreign material Neutrophils phagocytose bacteria Plasma cells synthesize antibodies Mast cells in skin secrete heparin that inhibits clotting and histamine that dilates blood vessels Adipocytes or fat cells store triglycerides 18 Tissues 9 BIO 201 Fibers of Connective Tissue Collagen fibers tough resistant to stretch, yet flexible tendons, ligaments and deep layer of the skin (dermis) Elastic fibers thin branching fibers made of elastin stretch & recoil like rubberband (elasticity) give skin, lungs and arteries ability to stretch and recoil Reticular fibers thin collagen fibers coated with glycoprotein form framework for spleen and lymph nodes 19 Types of Fibrous Connective Tissue Loose connective tissue contains gel-like ground gelsubstance between cells Dense connective tissue fibers fill the spaces between fib th b t cells 2 types varying in fiber orientation dense regular connective tissue dense irregular connective tissue 20 Tissues 10 BIO 201 Adipose Tissue Large, empty-looking cells with thin margins empty Nucleus pressed against cell membrane Subcutaneous fat beneath skin and surrounding organs 21 Energy storage, insulation, cushioning Cartilage Supportive connective tissue with rubbery matrix Chondroblasts produce cartilage matrix, once surrounded by cartilage chondrocytes y g y No blood vessels so diffusion must bring in nutrients and remove wastes injured cartilage heals slowly hyaline, fibrocartilage and elastic cartilage Major types of cartilage depend upon fiber types 22 Tissues 11 BIO 201 Cartilage Fibrocartilage Cartilage containing extensive parallel collagen fibers Resists compression and absorbs shock in some joints Pubic symphysis and intervertebral discs Hyaline Clear, glassy matrix; fine dispersed collagen fibers; chondrocytes in small clusters enclosed in lacunae Joints; supportive material in larynx, trachea, bronchi 23 Bone Spongy bone looks spongy in appearance delicate struts of bone always covered by compact bone Compact bone looks solid in appearance more complex arrangement cells and matrix vertically oriented 24 Tissues 12 BIO 201 Blood Variety of cells and cell fragments white blood cells, red blood cells, and platelets 25 Found in heart and blood vessels Mucous Membranes Consists of epithelium, connective (basal lamina or lamina propria) and underlying muscular tissues Lines passageways that open to the exterior: digestive, respiratory, urinary and reproductive Mucous coating and movement of cilia trap and remove 26 foreign particles and bacteria from internal surfaces of body Tissues 13 BIO 201 Cutaneous, Synovial and Serous Membranes Cutaneous membrane (skin) stratified squamous epithelium resting on layer of connective tissue relatively dry layer serves protective function secretes synovial fluid rich in hyaluronic acid into the joint covers organs and walls of body cavities, produces serous fluid Synovial membrane li S i l b lines j i t joints Serous membrane (serosa) internal membrane 27 Muscular Tissue Elongated cells that respond to stimuli by contracting Function is to exert physical force on other tissues move h d hand push blood through a vessel expel urine Important source of body heat Three types of muscle skeletal, cardiac and smooth 28 Tissues 14 BIO 201 Skeletal Muscle Long, cylindrical, unbranched cells with striations Movement, facial expression, posture, breathing, speech, swallowing and excretion 29 Cardiac Muscle Short branched cells with striations and intercalated discs Pumps blood 30 Tissues 15 BIO 201 Smooth Muscle Short cells; nonstriated Sheets of muscle in viscera; iris; hair follicles and sphincters Swallowing, GI tract functions, labor contractions, control of airflow, erection of hairs and control of pupil 31 Nervous Tissue Large neurons with long cell processes surrounded by much smaller glial cells lacking dendrites and axons Found in brain, spinal cord, nerves & ganglia Communication and control of bodily functions 32 Tissues 16 ...
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This note was uploaded on 05/18/2010 for the course BIO 201 taught by Professor Oberstein during the Spring '08 term at ASU.

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