Anatomy and Physiology: Tissue Level of Organization PDF

JLAT,RMT ANATOMY AND PHYSIOLOGY LECTURE NOTES Prepared by: John Larry Amis Taberna, RMT...

JLAT,RMT ANATOMY AND PHYSIOLOGY LECTURE NOTES Prepared by: John Larry Amis Taberna, RMT TOPIC 3: TISSUE LEVEL OF ORGANIZATION Histology – microscopic study of tissue structure Histopathology – microscopic study of diseased tissues Histologic/Histopathologic Techniques – involves the procedures in preparation of materials for such studies Pathologist – a physician who examines cells and tissues to help other physicians make accurate diagnoses TISSUE group of cells with similar structure and extracellular substances located between them cells that functions together to carry out specialized activities Changes in tissues can result in development, growth, aging, trauma, or disease Four basic tissue types according to structure and function 1. Epithelial tissue a. covers body surfaces and lines hollow organs, body cavities, and ducts and it also forms glands 2. Connective tissue a. protects and supports the body and its organs. b. Various types of connective tissues bind organs together c. help provide the body with immunity to disease-causing organisms 3. Muscular tissue a. composed of cells specialized for contraction and generation of force. b. muscular tissue generates heat that warms the body 4. Nervous tissue a. detects changes in a variety of conditions inside and outside the body b. responds to stimuli by generating electrical signals called nerve action potentials (nerve impulses) that activate muscular contractions and glandular secretions CELL JUNCTIONS contact points between the plasma membranes of tissue cells held cells together to form tissues 5 types: Tight junctions, Adherens junctions, Desmosomes, Hemidesmosomes, and Gap junctions JLAT,RMT  JLAT,RMT Tight Junction ✓ bind adjacent cells together and form permeability barriers ✓ prevent the passage of materials between epithelial cells because they completely surround each cell ✓ prevent the contents of organs from leaking into the blood or surrounding tissues. ✓ Materials that pass through the epithelial layer must pass through the cells, so those cells regulate what materials can cross ✓ Found in Epithelial lining of stomach, intestines, and urinary bladder Adherens Junction ✓ help epithelial surfaces resist separation during various contractile activities (ex. intestine movement) ✓ Plaque o a dense layer of proteins on the inside of the plasma membrane o Attaches both to membrane proteins and to microfilaments of cytoskeleton ✓ Cadherins o Transmembrane glycoprotein o inserts into the plaque from the opposite side of the plasma membrane, partially crosses the intercellular space and connects to cadherins of an adjacent cell ✓ Adhesion Belts o extensive zones that encircle the cell similar to the way a belt encircles the waist Desmosomes ✓ consist of Plaque and Cadherins similar to adherens but the plaque of desmosomes attaches to intermediate filament (consist of protein Keratin) instead of microfilaments. ✓ prevent epidermal cells from separating under tension ✓ prevent cardiac muscle cells from pulling apart during contraction Hemidesmosomes ✓ “hemi” – half ✓ resemble desmosomes, but they do not link adjacent cells. ✓ Anchors cells to the Basement membrane ✓ Integrins – transmembrane glycoprotein o inside the plasma membrane: attached to keratin o on the basement membrane: attached to laminin JLAT,RMT  JLAT,RMT Gap Junctions ✓ Function: transfer of nutrients, and perhaps wastes, in avascular tissues (lens and cornea of eye) ✓ allow the cells in a tissue to communicate with one another ✓ forms small channels that allow small molecules and ions to pass from one epithelial cell to another ✓ Connexins o Membrane protein that forms tiny fluid-filled tunnels called connexons that connect neighboring cells JLAT,RMT  JLAT,RMT COVERING AND LINING EPITHELIUM covers external and internal surfaces throughout the body Avascular – relies on the blood vessels of the adjacent connective tissue to bring nutrients and remove wastes by diffusion Two arrangements: o covering and lining various surfaces o forming the secreting portions of glands Apical (Free) surface o faces the body surface, a body cavity, the lumen (interior space) of an internal organ, or a tubular duct that receives cell secretions o may contain cilia or microvilli Lateral Surface o face the adjacent cells on either side o are of the cell junctions Basal Surface o deepest layer of epithelial cells o adhere to extracellular materials such as the basement membrane Basement Membrane o consists of a meshwork of protein molecules with other molecules bound to them o can function as a filter and as a barrier to the movement of cells (prevents metastasis of cancer) o two layers: ▪ Basal lamina closer to and secreted by the epithelial cells contains protein laminin, collagen, glycoproteins ▪ Reticular lamina closer to the underlying connective tissue contains proteins collagen produced by connective tissue cells called fibroblasts Functions of Epithelia: ✓ Protecting underlying structures (Ex. from abrasion) ✓ Acting as a barrier (Ex. prevent water loss) ✓ Permitting the passage of substances (ex. Gas exchange in lungs) ✓ Secreting substances (Ex. Sweat glands, mucous glands) ✓ Absorbing substances (Ex. epithelial cells of the intestines) Classification of Epithelia: According to number of Cell layer: o Simple Epithelium – single layer of cells o Stratified Epithelium – more than one layer of epithelial cells o Pseudostratified – simple epithelium that looks like two or more layers of cells because some of the cells are tall and reach the free surface According to Cell shape o Squamous epithelium – flat o Cuboidal – cube-like o Columnar – tall and thin JLAT,RMT  JLAT,RMT SIMPLE EPITHELIUM Single layer of cell EPITHELIUM STRUCTURE LOCATION FUNCTION ✓ Flat, often hexagonal cells Endothelium ✓ Diffusion ✓ resembles a tiled floor when ✓ Cardiovascular ✓ Filtration viewed from apical surface system ✓ Secretion Simple ✓ Nucleus: ✓ Lymphatic system ✓ Protection Squamous ▪ Flat and Central Mesothelium against friction ▪ Oval or spherical in ✓ Serous membrane shape (Pleura, Peritoneum, Pericardium) Air sacs of lungs Glomerulus ✓ Cube-shaped Cells ✓ surface of ovary ✓ Secretion and ✓ some cells have microvilli ✓ Kidney tubules absorption by (kidney tubules) or cilia (terminal ✓ lining of terminal cells of the Simple Cuboidal bronchioles of the lungs) bronchioles of the lungs kidney tubules ✓ Nucleus: ✓ Movement of ▪ Round, central mucus by ciliated cells ✓ Non-ciliated columnlike cells ✓ Lines gastrointestinal ✓ Secretion and ✓ Nucleus: tract (from stomach to absorption ▪ Oval near the base anus) ✓ Secrete mucus Non-ciliated ✓ Microvilli – apical surface ✓ bronchioles of lungs ✓ Simple Columnar ✓ Goblet cells – apical surface ✓ uterus, ▪ modified columnar ✓ uterus or uterine tubes epithelial cells that secrete mucus ✓ Ciliated columnlike cells ✓ Respiratory tract ✓ moves mucus ✓ Nucleus: ✓ Uterine (fallopian) tubes ✓ Coughing and ▪ Oval near base ✓ Uterus sneezing speed Ciliated ✓ Goblet cells are usually ✓ some paranasal sinuses up movement Simple Columnar scattered/dispersed of cilia and mucus ✓ move oocytes expelled from ovaries Non-ciliated ✓ cells are tall and thin and reach ✓ Lines epididymis, larger ✓ Absorption Pseudostratified the apical surface and others do ducts of many glands, and Secretion Columnar not and parts of male urethra Ciliated ✓ Contains cells that extend to ✓ Lines airways of most of ✓ Secrete and Pseudostratified surface and secrete mucus upper respiratory tract move mucus Columnar (globlet cells) or bear cilia JLAT,RMT  JLAT,RMT STRATIFIED EPITHELIUM has two or more layers of cells EPITHELIUM STRUCTURE LOCATION FUNCTION ✓ Apical – Squamous Keratinized: ✓ Protection: ✓ Deep – squamous, cuboidal to ✓ superficial layer of ▪ abrasion columnar skin ▪ water ✓ Basal cell divides → new cells Non-keratinized loss pushes old cells → dehydrated ✓ lines wet surfaces ▪ UV Stratified → keratinized → cell die → (lining of mouth, radiation Squamous cell junctions destroyed → esophagus, part of ✓ first line of sloughed off epiglottis, part of defense against pharynx, and vagina) microbes. Keratin - a tough, fibrous and covers tongue intracellular protein which amount increases in cell as it move away from nutritive blood supply and organelles die Stratified ✓ cells in apical layer are cube- ✓ Ducts of adult sweat ✓ Protection Cuboidal shaped; fairly rare type glands ✓ Limited ✓ Esophageal glands secretion and ✓ Part of male urethra absorption Stratified ✓ Basal layer - shortened, ✓ Lines: ✓ Protection and Columnar irregularly shaped cells ▪ part of urethra secretion ✓ Apical layer - has columnar ▪ small areas in cells anal mucous ✓ Uncommon membrane TRANSITIONAL EPITHELIUM EPITHELIUM STRUCTURE LOCATION FUNCTION ✓ has a variable appearance ✓ Lines urinary bladder ✓ Allows urinary (transitional) and portions of ureters organs to ✓ Multiple layers and elasticity and urethra stretch and make it ideal for lining hollow maintain structures (urinary bladder) protective subject to expansion lining while Transitional ✓ Relaxed – looks like stratified holding variable cuboidal epithelium, except amounts of apical layer cells are large and fluid without rounded rupturing ✓ Stretched - cells become flat, giving the appearance of stratified squamous epithelium PAPANICOLAOU TEST “pap test” or “pap smear” recommended to be performed every three years beginning at age 21 of female microscopic examination of vaginal or cervical epithelial cells that have been scraped off the apical layer of a tissue performed mainly to detect early changes in the cells of the female reproductive system that may indicate a precancerous condition or cancer JLAT,RMT  JLAT,RMT GLANDULAR EPITHELIUM Functions mainly in Secretion Glands – an epithelium that secretes substances onto a surface, into a cavity, or into the blood in the absence of ducts Classifications: o Endocrine ▪ glands have no ducts and empty their secretions into the blood ▪ hormones - enter the interstitial fluid and then diff use into the bloodstream without flowing through a duct. It has a far reaching effect ▪ Ex. Thyroid Gland and Pancreas o Exocrine ▪ secrete their products into ducts that empty onto the surface of a covering and lining epithelium such as the skin surface or the lumen of a hollow organ ▪ secretions of exocrine glands have limited effects ▪ Unicellular Single-celled gland Goblet cells – important unicellular exocrine glands that secrete mucus directly onto the apical surface of a lining epithelium ▪ Multicellular composed of many cells that form a distinctive microscopic structure or macroscopic organ ex. sudoriferous (sweat), sebaceous (oil), and salivary glands. Two Criteria o Branched (compound) or Unbranched (Simple) o Shape of secretory portion of the gland ▪ Tubular Glands – Tubular secretory part ▪ Acinar (“acin”-berry) – rounded secretory portions (aka alveolar) ▪ Tubuloacinar - have both tubular and rounded secretory parts SIMPLE GLANDS TYPE DESCRIPTION Example ✓ glands in the large intestine Tubular secretory part is Simple Tubular straight and attaches to a single unbranched duct ✓ gastric glands. Tubular secretory part is Simple Branched branched and attaches to a Tubular single unbranched duct ✓ Sweat glands Tubular secretory part is Simple Coiled coiled and attaches to a single Tubular unbranched duct JLAT,RMT  JLAT,RMT ✓ glands of penile Secretory portion is rounded, urethra Simple Acinar attaches to single unbranched duct ✓ sebaceous glands Simple branched Rounded secretory part is acinar branched and attaches to a single unbranched duct COMPOUND GLANDS TYPE DESCRIPTION Example ✓ bulbourethral (Cowper’s) glands Compound Secretory portion is tubular tubular and attaches to a branched duct ✓ mammary glands. Secretory portion is rounded Compound Acinar and attaches to a branched duct ✓ Acinar glands Secretory portion is both ✓ Glands of pancreas Compound tubular and rounded and Tubuloacinar attaches to a branched duct Functional Classification of Exocrine Glands functional classification of exocrine glands is based on how their secretions are released secretory processes begins with the endoplasmic reticulum and Golgi complex working together to form intracellular secretory vesicles that contain the secretory product Merocrine glands ✓ Secretions are synthesized on ribosomes attached to RER; processed, sorted, and packaged by the Golgi complex; and released from the cell in secretory vesicles via exocytosis. ✓ (Ex. Salivary glands and Pancreas) Apocrine glands ✓ Accumulates secretory product at the apical surface of secreting cell. ✓ Portion of the cell pinches off by exocytosis from the rest of the cell to release the secretion. ✓ Cell repairs itself. ✓ (Ex. Mammary gland and apocrine Sweat gland) JLAT,RMT  JLAT,RMT Holocrine glands ✓ accumulate a secretory product in their cytosol. ✓ As the secretory cell matures, it ruptures and becomes the secretory product ✓ secretion contains large amounts of lipids from the ruptured plasma membrane and intracellular membranes ✓ (Ex. Sebaceous gland of skin) CONNECTIVE TISSUES found throughout the body highly vascular and has nerves (except cartilage and tendons) Extracellular Matrix o Material located between its widely spaced cells (separates cells from one another) o It determines tissue’s qualities ▪ Cartilage – extracellular matrix is firm but pliable ▪ Bone – extracellular matrix is hard and inflexible o Major components: ▪ Protein fibers Collagen fibers – “glue” producing; flexible but resist stretching Reticular fibers – consists of collagen arranged in fine bundles coated with glycoprotein. Provide support and strength (ex. blood vessel walls) Elastic fibers – coiled structure that can recoil to their original shape after being stretched. Protein elastin surrounded by a glycoprotein fibrillin ▪ Ground substance consists of nonfibrous protein and other molecules; forms shapeless background may be fluid, semifluid, gelatinous, or calcified Fibronectin - main adhesion protein of connective tissues o binds to both collagen fibers and ground substance o attaches cells to the ground substance ▪ Fluid Proteoglycan o Forms a core protein where glycosaminoglycans projects like a bristles of brush o Glycosaminoglycans (GAGs) - chondroitin sulfate, dermatan sulfate, and keratan sulfate ▪ trap water, making the ground substance more jellylike JLAT,RMT  JLAT,RMT GLYCOSAMINOGLYCANS GAGs Function Others ✓ binds cells together ✓ Viscous, slippery substance ✓ lubricates joints ✓ Hyaluronidase ✓ helps maintain shape of An enzyme that break eyeballs down Hyaluronic Acid Hyaluronic Acid for a ground substance to be more liquid Produced by: ▪ WBC ▪ Sperm cell ▪ Bacteria ✓ Provides support and adhesiveness in cartilage, bone, skin, and Chondroitin Sulfate blood vessels Dermatan Sulfate ✓ skin, tendons, blood vessels, and heart valves Keratan Sulfate ✓ bone, cartilage, and the cornea of the eye Functions of Connective Tissues ✓ Enclosing and separating other tissues o forms capsule around organs (ex. in liver and kidney) o forms layers that separate tissues and organs (ex. between muscles, arteries, veins, and nerves) ✓ Connecting tissues to one another o Ex. Tendons (Muscle to bone); Ligaments (Bone to bone) ✓ Supporting and moving parts of the body o Joints between bones ✓ Storing compounds o Adipose tissue (fat) stores high-energy molecules o Bones store minerals, such as calcium and phosphate ✓ Cushioning and insulating o Adipose tissue cushions and conserve heat ✓ Transporting o Blood transports nutrients, oxygen, hormones, etc. ✓ Protecting o Cells of immune system o Bones protect underlying organs Formation of Connective Tissue Cells JLAT,RMT  JLAT,RMT Connective Tissue Cells ✓ It varies according to the type of tissue ❖ Fibroblasts o large, flat cells with branching processes o cells that form fibers and ground substance in the extracellular matrix of fibrous connective tissue and usually are the most numerous o Fibrocyte – cells that maintain the fibrous connective tissue ❖ Macrophages o phagocytes that develop from monocytes o Fixed macrophage - reside in a particular tissue (alveolar macrophages or splenic macrophages) o Wandering macrophage - have the ability to move at sites of infection or inflammation ❖ Plasma cells (Plasmocyte) o found in many places in the body but mostly in connective tissue (GIT and Respiratory tract) ❖ Mast Cells (Mastocytes) o involved in the inflammatory response ❖ Adipocytes o fat cells or adipose cells that store triglycerides (fats). ❖ Leukocytes (WBCs) o Migrates from blood to site of infection in the connective tissue CLASSIFICATION OF CONNECTIVE TISSUE Embryonic CT Mature CT ✓ Mesenchyme Connective Tissue Proper Supporting CT Liquid CT ✓ Mucous (Mucoid) CT Loose CT Cartilage Blood ✓ Areolar CT ✓ Hyaline Cartilage Lymph ✓ Adipose tissue ✓ Fibrocartilage ✓ Reticular CT ✓ Elastic Cartilage Dense CT Bone Tissue ✓ Dense Regular CT ✓ Compact Bone ✓ Dense Irregular CT ✓ Spongy Bone ✓ Elastic CT Embryonic Connective tissue – present in embryo or fetus Mature Connective tissue – present at birth and persist for life EMBRYONIC CONNECTIVE TISSUE Type Structure Location Function ✓ irregularly shaped ✓ under skin and along ✓ Forms almost all mesenchymal cells developing bones of other types of Mesenchyme ✓ semifluid ground embryo connective tissue substance with ✓ blood vessels of adult delicate reticular fibers Mucous (Mucoid) ✓ has widely scattered ✓ Umbilical cord of ✓ Support Connective Tissue fibroblasts fetus ✓ viscous, jellylike ground substance that contains fine collagen fibers. JLAT,RMT  JLAT,RMT MATURE CONNECTIVE TISSUE Connective Tissue Proper Loose Connective Tissue Type Structure Location Function ✓ most widely ✓ subcutaneous layer ✓ Strength distributed deep to skin ✓ Elasticity connective tissues ✓ superficial region of ✓ Support ✓ Fibers (arranged dermis of skin randomly): ✓ around blood vessels Collagen and nerves Elastic ✓ Areolar Connective Reticular Tissue ✓ Cells: Fibroblasts macrophages plasma cells adipocytes mast cells, few WBCs ✓ Ground substance All GAGs JLAT,RMT  JLAT,RMT ✓ specialized for ✓ subcutaneous areas ✓ Thermal insulator storage of ✓ mammary glands ✓ Energy storage triglycerides (fats) ✓ Protects organs Adipose Tissue ✓ full of lipids that the obesity = increased cytoplasm and adipocyte = increased nucleus is pushed to blood vessel = heart the cell periphery works harder = high blood pressure Reticular Tissue ✓ Fine network of ✓ Within the lymph ✓ Provides filtering reticular fibers nodes, spleen, bone structure for lymph arranged irregularly marrow nodes and spleen JLAT,RMT  JLAT,RMT MATURE CONNECTIVE TISSUE Connective Tissue Proper Dense Connective Tissue contains more fibers (thicker and more densely packed) but have fewer cells than LCT Type Structure Location Function ✓ Matrix composed of ✓ Tendons ✓ Provides strong collagen fibers ✓ Ligaments attachment between Dense Regular running in the same various structures Connective Tissue direction ✓ withstands pulling (tension) along the direction of fiber ✓ made up of collagen ✓ occurs in sheets, such ✓ Provides tensile fibers; usually as fasciae (tissue (pulling) strength in irregularly arranged beneath skin and many directions Dense Irregular with a few fibroblasts around muscles and Connective Tissue other organs) ✓ fibrous pericardium of heart ✓ deeper region of dermis of skin Elastic Connective ✓ predominantly elastic ✓ Lung tissue ✓ strong and can recoil Tissue fibers with fibroblasts ✓ bronchial tubes to original shape after between them ✓ vocal cords, being stretched ✓ suspensory ligaments ✓ important to normal of penis functioning of lung tissue (recoils in exhaling) JLAT,RMT  JLAT,RMT TO BE CONTINUED… JLAT,RMT