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Tissues Definition- group of similar cells that together perform a specialized function Histology- study of tissues Basic types – Epithelial- covers body surfaces, lines cavities, organs, ducts, and forms glands – Connective- protection, supports body, binds organs together, stores energy as fat, produces immunity – Muscle- movement – Nervous- initiates and transmits impulses that coordinate body activity Epithelial tissue Consist of closely packed cells, little intercellular fluid Single or multiple layers Avascular- no blood vessels Have nerve supply High turn over rate- constantly making more Functions – Protection, filtration, lubrication, secretion, digestion, absorption, transportation, excretion, sensory receptors, reproduction Simple- single layer found where transport is needed Stratified- 2+ layers used for protection Psuedostratified- one layer but looks like more Squamous- flat and attached together like tiles Cubiodal- cube or hexagonal shape – Produce secretions (sweat, enzymes) – Can absorb- intestinal tract Simple Squamous Simple cuboidal Stratified squamous Stratified cuboidal Columnar- tall and cylindrical – Protection of underlying tissue – Specialized for secretion and absorption Transitional – Vary in shape – Flat to columnar due to stretching Stratified columnar Simple columnar Transitional Pseudostratified columnar Glandular Epithelium Functions for secretions- cells lie below outer epithelium Endocrine- ductless- hormones Exocrine- secreted into ducts- mucous, sweat, oil, digestive enzymes Connective Tissue Most abundant tissue in the body All connective tissue comes from embryonic mesenchyme – Stem cells Connective Tissue Proper Intercellular material and matrix – Hyaluronic acid Viscous, slippery substance that binds cells – Chondroitin sulfate Provides support and adhesiveness in cartilage, bone, skin, and blood vessels Loose (areolar) tissue Most widely distributed Location- widespread- mucous membranes, around blood Fibrous vessels and nerves, subcutaneous – Collagenous (white) Tough, resistant to pulling Made of collagen – Elastic (yellow) Smaller, provides strength, skin, blood vessels, and lungs – Reticular Thin, immature collagen Collagen coated with glyco-protein Supports walls of blood vessels, nerve cells, and smooth cells Forms stroma- framework of spleen and lymph nodes Cells Fibroblasts- most numerous, especially active Macrophages- large and function to engulf in repair bacteria and cellular debris by phagocytosis Plasma cells- secrete antibodies- immunity Melanocytes- pigmented cells below deepest layer of skin- produce melanin Mast cells- produce heparin (anti-coagulant) and histamine- a chemical that dilates small blood vessels during inflammation Adipose tissue Cells called adipocytes- fat storage Shape – Signet ring shaped Location – Subcutaneous Functions – Good insulation, energy reserve, protection of internal organs Dense collagenous tissue – More numerous cells and thicker fibers – Location: muscles, ligaments, tendons – Functions: provide elasticity Elastic tissue – Structure: freely branched fibersstretch and snap back – Location: muscles, ligaments, tendons – Function: allow for elasticity Cartilage- no blood vessels or nerves (except in the perichondrium- tissue around carilage) – Characteristics Dense network of collagen and chondroitin sulfate Resistant strong – Types Hyaline- gristle- bluish white color, shiny, most abundant – Found in embryonic skeleton (exclusively) – Found on end of long bones and costal Fibrocartilage – Found in matrix to give strength – Bundles of collagen fibers Elastic – Threadlike network for elasticity Hyaline cartilage Elastic Cartilage Cartilage from the external ear Osseous tissue (bone) Skeletal system- basic unit called an osteon- made of: – Lamellae Concentric rings of hard matrix- calcium – Lacunae Spaces between lamellae- has Haversian canal- contains blood vessels and nerves Vascular tissue (blood) Connective tissue Plasma- mostly water with dissolved substances (nutrients, wastes, enzymes, hormones, respiratory gasses) – Erythrocytes- red blood cells – Leucocytes (WBC)- phagocytes, immunity – Platelets- clotting Other tissues Muscle tissue- highly specialized cells for contraction – Smooth- walls of internal organs (hollow)- involuntary- non striated – Cardiac- wall of heart- involuntarystriated- 1 nucleus – Skeletal- striated- voluntary- fibers are cylindrical and striated- multiple nuclei Smooth muscle Skeletal muscle Cardiac muscle Nerve tissue – Consists of neurons – Neurons Calls that receive stimuli and convert to impulse- carry impulses to other nerves, muscles, or glands – Dendrites- converging branches that take impulse to cell body – Axons- long, single strand that conduct impulses AWAY from cell body – Neuroglea Cells for protection and support of neurons DO NOT CONDUCT Common sites of tumors Membranes – Mucous- line cavities that open to the outside world – Serous- line cavities that do not open to outside, cover organs, produce serous fluid – Synovial- line freely moving joints, not open to outside
