Chapter 3 Tissues PDF

Chapter 3 – Tissues I. II. Introduction a. Histology (histo- = tissue, -logy = study of): study of tissues b. Pathologist: physician who studies cells and tissues to make dx c. 4 Types of Tissue i. Epithelial – covers body surfaces, lines hollow organs/cavities/ducts, forms glands. Allows interactio...

Chapter 3 – Tissues I. II. Introduction a. Histology (histo- = tissue, -logy = study of): study of tissues b. Pathologist: physician who studies cells and tissues to make dx c. 4 Types of Tissue i. Epithelial – covers body surfaces, lines hollow organs/cavities/ducts, forms glands. Allows interaction w/internal & external envir ii. Connective – protects & supports body: binds organs, stores energy (fat reserves), immunity iii. Muscular – contraction & generation of force, generates heat iv. Nervous – detects changes in/out of body, responds w/elec signals (AP’s) > ms. contraction & gland secretion Cell Junctions – what hold cells together a. 5 types Type Sx / Components Fx Location Draw Tight Jxn Transmembrane protein Seals passages of adjacent cells Stomach, Intestine Urinary bladder Adherens Jxn Inside: plaque Adhesion belts circles cell PM proteins Epithelial cells microfilaments (actin) Connects plaque to cadherins of Intestine Outside: cadhedrins adjacent cell (transmembrane *resists separation glycoproteins) Desmosomes Like adherens except: Intermediate filaments attach to Plaque > cytoskeleton desmosomes on other side of Epidermis intermediate filaments (keratin) cytosol (cell) Cardiac ms. cell *provide sx stability Cadherins *prevent separation Hemidesmosomes Plaque > cytoskeleton intermediate filaments (keratin) Integrins attach basilar cell layer to basement membrane via Basal cell layers Integrins (transmembrane laminin glycoproteins) Gap Jxn Laminin (protein on BM) Connexins (membrane proteins) Intercellular gap Form connexons (tunnels) Ions, sm molecules flow through Connects cytosol of adjacent cells Lens Cornea of eye Embryo (chem & elec signals regulating growth) Ms of heart, GI, uterus b. Comparison of Epithelial & Connective Tissue Epithelial Cell organization Tightly packed Blood vessel supply None Location Surface layers Not covered by other tissue (except w/in blood vessels) Always next to connective tissue (exchange of O2, nutrients, toxins) III. Connective Loosely packed ↑↑↑↑ Always b/n other tissues Epithelial Tissue a. Cells arranged in continuous sheets, little intercellular space b. 2 general patterns i. Surface – covers & lines various surfaces ii. Glands – secreting portions c. Specialized surfaces i. Apical – faces body surface, lumen (interior space) of organ or tubular duct, may have microvilli or cilia (superficial) ii. Lateral – walls facing adjacent cells, different types of jxn’s iii. Basal – opposite apical, deepest layer of cells adhere to extracellular material (basement membrane = BM) d. Basement membrane – extracellular i. 2 layers 1. Basal lamina (thin layer) – secreted by epithelial cells, contains laminin (hemidesmosomes), collagen & proteoglycans 2. Reticular lamina – closer to underlying tissue, composed of proteins (collagen) from fibroblasts ii. Fx’s 1. Secure epithelial cells to BM 2. Form migration surface (for cells during growth & wound healing) 3. Restrict passage of larger molecules 4. Filtration of blood in kidneys e. Has own nerve supply f. Avascular – no blood vessels: exchange of substances (O2, nutrients, toxins) by diffusion g. Subject to stress/injury – high rate of cell division h. Primary Fxn’s i. Protection – makes barrier ii. Filtration – allow selected molecules/particles through iii. Secretion – sends substance out of cell (mucus, sweat, enzymes) iv. Absorption – brings substance into cell (fluids, digested food) v. Excretion – sends substances out of body i. Classification - Surface Epithelium i. By Layers Arrangement /Type by Layer Simple (unilaminar) Pseudostratified (pseudo = false) SX Single layer of cells Fx Diffusion, osmosis, filtration, secretion, absorption Cell nuclei at different levels Single layer attached to BM May have cilia (apical) Others secrete mucus (modified goblet) Ciliated: help move particles Non-ciliated: often have microvilli to increase surface area for absorption ii. By Shape Arrangement /Type by Shape Squamous Sx Thin, pancake looking Fx Rapid passage of substance Cuboidal (like a cube) Columnar As tall as they are wide May have microvilli (apical) Taller than wide Apical microvilli or cilia Secretion/absorption Secretion/absorption Protect underlying tissue Stratified (multilaminar) 2+ layers Protection Transitional Shape changes from Squamous to cuboidal Allows for stretching as in bladder Draw iii. Multiple combinations of 2 classifications Simple Epithelium A. Simple squamous epithelium 1. endothelium – inner lining (heart, blood/lymph vessels) 2. mesothelium – serous membranes, alveoli, kidney, B. Simple cuboidal epithelium (+/- microvilli): ovary, lens of eye, retina, kidney tubules, sm ducts, thyroid, pancreas C. Simple columnar epithelium 1. Non-ciliated: microvilli lining GI tract, gall bladder, repro & respiratory tracts 2. Ciliated:lines bronchioles, uterine tubes, ventricles in brain D. Pseudostratified columnar epithelium 1. Non-ciliated: epididymis, male urethra, parotid glands 2. Ciliated: most of upper respiratory tract Stratified epithelium A. Stratified squamous epithelium: 1st line of defense 1. nonkeratinized: wet surfaces – mouth, tongue, esophagus, epiglottis, pharynx, vagina 2. keratinized: superficial layer of skin B. Stratified cuboidal epithelium (rare): sweat & esophageal glands, part of male urethra C. Stratified columnar epithelium (rare): part of urethra, esophageal gland, anal mucous membrane, eye conjunctiva D. Transitional epithelium (urothelium) – urinary tract/system, part of ureters & urethra j. Classification – Glandular epithelium: secretes substances via ducts onto a surface or into the blood stream i. Endocrine glands – secrete hormones which enter interstitial fluid (ISF) and diffuse into bloodstream (no duct) 1. Pituitary, thyroid, adrenal glands ii. Exocrine glands – secrete products into ducts > surface of covering or lining epithelium (skin, lumen of hollow organ) > out of body 1. Products = digestive enzymes, mucus, sweat, oil, earwax, saliva 2. Glands = sudoriferous (sweat) glands, salivary glands iii. Pancreas, ovaries and testes are mixed (endocrine and exocrine) iv. Sx Classification 1. Unicellular – single celled a. Goblet cells secrete mucus (exocrine) – may also be classified as modified simple columnar epithelium 2. Multicellular – most exocrine cells, based on branching pattern and shape of duct a. Branching pattern i. Simple – one duct (all 5 types under ‘b’) ii. Compound – duct branches (tubular, acinar or tubuloacinar) b. Shape of secreting portion i. Tubular ii. Branched tubular iii. Coiled tubular iv. Acinar v. Branched acinar v. Fx Classification 1. Merocrine/Eccrine glands a. Begins with RER/Golgi > intracellular secretory vesicles > exocytosis b. Most common c. Salivary glands & pancreas 2. Apocrine glands a. Secretory substance accumulates at apical membrane, pinches off, cell repairs & repeat b. Mammary glands secrete milk this way c. Sweat gland (inappropriately named “apocrine”, actually fx like merocrine) 3. Holocrine glands a. Substance accumulates in cytosol until cell bursts (adding lipids from PM to secretion) b. Sebaceous gland of skin IV. Connective Tissue a. Intro Most abundant and widely distributed = cells + ECM i. Terms 1. -blast = “to bud or sprout”: fibroblast (loose & dense CT), chondroblast (cartilage), osteoblast (bone) 2. -cyte = “mature cell”, fibrocyte, chondrocyte, osteocyte: ↓ cell division & ECM formation; monitor/maintain ECM ii. Cell Types 1. Fibroblasts: large, flat, w/branching processes, most common in CT 2. Macrophages: phagocytes (eaters) from monocytes (WBC) a. Fixed – stay in 1 type of tissue (ie. alveolar in lungs, splenic in spleen) b. Wandering – move through tissue to site of infection 3. Plasma cells (plasmocytes): many places in body, mostly GI & respiratory tracts 4. Mast cells (mastocytes): inflammatory response, bind to/ingest/kill bacteria 5. Adipocytes: fat cells – store triglycerides for energy, protection 6. White Blood Cells (WBC) – respond to certain conditions, 5 types (neutrophils, eosinophils, basophils, lymphocytes, macrophage) iii. Extracellular matrix (ECM) 1. Material b/n widely spaced cells 2. Determines tissues qualities (cartilage = firm/pliable, bone = hard/inflexible) 3. Not usually on body surfaces 4. Highly vascular (except cartilage; tendons scant) 5. Has nerve supply (except cartilage) 6. = ground substance + protein fibers a. Ground substance i. Water & lg organic molecules (polysaccharides = glycosaminoglycans (GAG’s) 1. GAG’s (not hyaluronic acid) combine with proteoglycans: together they trap water, make it jelly-like a. Chondroitin sulfate (polysaccharide) & Glucosamine (proteoglycan) – helpful with OA? b. Hyaluronic acid: viscous substance, binds cells, lubricates joints, shapes eyeball i. WBC, sperm, some bacteria produce hyaluronidase > breaks up hyaluronic acid, liquifies ECM ii. Protein fibers 1. Collagen fibers a. Strong, resist tensile forces (pulling/stretching), yet flexible b. Collagen is the most abundant protein in body (25%) c. Often in parallel bundles d. Found in bone, collagen & ligaments 2. Elastin fibers a. Sm diameter, form fibrous network b. Elastin protein surrounded by glycoprotein called fibrillin (strength & stability) i. Defective fibrillin gene > Marfan’s syndrome > weakening of elastin fibers c. Can stretch up to 150% of length without breaking and can recoil (elasticity) d. Found in skin, blood vessel walls, lung tissue 3. Reticular fibers (reticul- = net) a. Collagen in bundles with glycoprotein coat b. Thin branching networks c. Form basement membrane, stroma (covering) of soft organs (spleen & lymph nodes) d. Provide support & strength b. Classification of CT First a little intro on development Sperm + egg (oocyte) > zygote (single cell) > multiple divisions > blastula 3 germ layers develop 1. Ectoderm – Epidermis, hair, nails, epithelium of skin & mammary glands, nervous tissue, eye & ear sx’s, head (skeletal & CT) 2. Mesoderm – Muscle, most connective tissue, blood & lymph vessels, dermis, kidneys, ureters & adrenal glands, gonads 3. Endoderm - Most epithelial lining, gametes i. Embryonic CT (2 types) 1. Mesenchyme – in embryo through first 8 wks of pregnancy a. From the mesoderm b. Forms most CT 2. Mucous (mucoid) CT – in fetus, from 9 wks through delivery ii. Mature CT 1. CT Proper a. Loose CT i. Areolar CT – packing material, subcutaneous layer, papillary region of dermis, mucous mem, nerves, blood vessels, ii. Adipose tissue – adipocytes store triglycerides. White adipose in adults accumulate blood vessels (>HTN), brown adipose in fetus/infants rich in mitochondria/blood supply. Found with areolar CT: subcutaneous layer, around heart/kidneys, yellow bone marrow, padding around joints, behind eyeball. iii. Reticular CT – stroma (framework) of liver, spleen, lymph nodes; red bone marrow; reticular lamina of BM, around blood vessels & muscles. Also filters/removes worn-out blood cells in spleen & microbes in lymph node. b. Dense CT i. Dense regular CT – collagen fibers regularly arranged; mostly tendons & ligaments (low blood supply – slow to heal), provides strong attachments. ii. Dense irregular CT – irregularly arranged collagen fibers in sheets (fasciae), reticular (deeper) region of dermis, fibrous pericardium, periosteum, perichondrium, joint capsules, membrane capsules of organs (kidney, liver, testes, lymph nodes), heart valves. Provides tensile/pulling strength in many directions iii. Elastic CT – primarily elastic fibers: lung tissue, walls of arteries, trachea, bronchial tubes, true vocal tubes, suspensory ligaments of penis, some vertebral ligaments. Allows stretching and recoil. 2. Supporting CT a. Cartilage: i. chondroitin sulfate (collagen + elastin) gives it strong resilience (assume original shape) & compression (resistant to being crushed). ii. Secretes antiangiogenesis factor – prevents blood vessel growth (possible cancer tx?) iii. Cells = chondrocytes, reside in lacunae (“little lakes”) in ECM iv. Covered by dense irreg CT = perichondrium (has blood vessels, nerves and is source of new cartilage) v. Avascular vi. Precursor to bone (embryonic skeleton), persists as growth plates & lubricated articular surfaces vii. 3 Types of cartilage 1. Hyaline cartilage – most abundant yet weakest cartilage, bluish-white shiny surface, often perichondrium, prominent chondrocytes in lacunae a. Articular: ends of long bones b. Costal: ends of ribs attaching to sternum (weak but flexible) c. Respiratory: nose, part of larynx, bronchi/bronchiole tubes 2. Fibrocartilage – strongest of all cartilage, no perichondrium, scattered chondrocytes a. Pubic symphysis, intervertebral discs, menisci of knee, portions of tendons inserting into cartilage 3. Elastic cartilage – chondrocytes in threadlike network of elastin fibers, has perichondrium, provides shape & elasticity. a. Epiglottis, external ear (auricle), and auditory (eustachian tubes) b. Bone Tissue i. Fx: supports soft tissue, protects delicate sx’s & acts as levers w/muscular system for mvmt, store Ca2+ and Phosphorus, house red bone marrow (produce blood cells), contains yellow marrow (triglyceride storage) ii. Bones are composed of several connective tissues: 1. Bone (osseous) tissue 2. Periosteum – outer lining 3. Red & yellow marrow 4. Endosteum – inner lining iii. 2 classifications based on how ECM (mix of collagen, Ca2+, inorganic salts) & Cells organized 1. Compact bone a. Basic unit = osteon/haversian system i. Lamellae (little plates) – concentric rings of ECM (Ca2+ & phosphates) & collagen ii. Lacunae – spaces containing mature osteocytes iii. Canaliculi (little canals) – contain processes of osteocytes: provide transport for nutrients & toxins iv. Central (haversian) canal – contains blood vessels & nerves 2. Spongy bone a. Lacks osteons b. Contains slender bones: trabeculae i. House lamellae, osteocytes, lacunae & canaliculi ii. Space b/n trabeculae = red bone marrow c. Liquid CT i. Blood 1. Plasma – water, nutrients, wastes, enzymes, plasma proteins, hormones, respiratory gases, & ions 2. Formed elements a. Erythrocytes (RBC): transport O2 in to body, CO2 out to lungs b. Leukocytes (WBC): phagocytosis, immunity & allergic rxn’s c. Platelets: blood clotting ii. Lymph 1. ECF that flows into lymphatic vessels 2. Similar to plasma, but less protein 3. Contents vary depending on body part: intestines (↑ lipid), leaving lymph nodes (↑ WBC) V. Membranes – flat sheets of pliable tissue covering/lining body part a. 2 Classifications i. Epithelial Membranes (3 types): most abundant, consisting of epithelial layer + underlying CT 1. Mucous Membranes a. Lines a body cavity directly opening to the exterior: digestive, respiratory, reproductive and (most of) urinary tract b. Tight jxn’s: limit microbes/pathogens from penetrating, materials can’t leak through c. Goblet cells of epithelium produce mucus > prevents drying out i. Also traps particles in respiratory tract and lubricates food in GI d. Epithelium secretes enzymes for digestion, site of food/fluid absorption e. Structures vary in different parts of body (intestines simple columnar, lg airways pseudostratified ciliated columnar f. CT layer of mucous membrane = lamina propria (one’s own) = areolar CT i. Supports epithelium, binding it to underlying sx’s, giving some flexibility & protection ii. Holds blood vessels, source of O2/nutrients for epithelium and port for CO2 & wastes 2. Serous (watery) Membranes: pleura, pericardium, peritoneum a. Lines a body cavity not exposed to external environment (thoracic/abdominal cavities), covering organs b. Areolar CT covered by simple squamous epithelium (SSE) c. 2 layers i. Parietal layer – attaches to cavity wall ii. Visceral layer – adheres to organs within the cavity d. Mesothelium allows lubricant from capillaries to penetrate mesothelial surface 3. Cutaneous Membranes a. Skin = epidermis (keratinized stratified squamous epithelium KSSE) + dermis (dense irreg CT + areolar CT) VI. VII. ii. Synovial Membranes (syn = together) 1. Line joints 2. Produce slimy substance like uncooked egg white (hence “ova”) 3. Lack epithelium 4. Composed of synoviocytes, closer to inner joint and areolar & adipose tissue deeper a. Nourishes cartilage covering bones & contains macrophages (remove microbes & debris) Muscular Tissue a. Cells = muscle fibers (myocytes) b. Use ATP to generate force > body mvmt, maintains posture & generates heat, provides protection c. 3 types Skeletal Cardiac (myocardium) – only in heart Draw Nuclei Voluntary Sx Multinucleated Voluntary Striated, cylindrical & long 1-2 nuclei Involuntary Striped Intercalated disc (Gap jxn’s & desmosomes) Fx Moves skeleton& soft tissue Posture Generates heat Protects some tissue/organs Allows rapid passage of electrical current Pumps blood through CV sys Smooth Uninucleated (one nucleus) Involuntary Non-striated Spindle shaped (think in middle, thin ends) Short cells Lines hollow organs (stomach, intestine, blood vessels, urinary, reproductive & respiratory tracts); Moves food, blood & urine Nervous Tissue – fx = communication & control of body fx’s a. Neurons (nerve cells) – initiate & conduct electrical activity in body i. Cell body (soma) – contains nucleus/organelles ii. Dendrites – receive info from other sources, into cell body iii. Axon – thin, long process exiting cell body, transmitting action potential (AP) iv. Telodendria & synaptic knobs – branching & ends of axon v. Neurotransmitter – chemical messenger released by neuron to influence another neuron/muscle/gland cell b. Neuroglia (glue) – cells supporting neurons (provide nutrients/remove wastes) i. 5x’s more abundant that neurons ii. May be more important than neurons in determining intelligence iii. Several types of neuroglia (discussed later) VIII. Aging & Tissues a. As tissues age i. Epithelial tissue thins with age: ↑ skin & ms membrane disorders, wrinkles, bruising ii. Connective tissue gets more fragile: loss of bone density, ↑ fx’s iii. Loss of muscle tissue mass and strength, ↓ pumping efficacy of heart, ↓ smooth-ms activity (GI tract) iv. Glucose binds to proteins in/out of cell > cross-links > stiffening / ↓ elasticity v. ↑ collagen & thickening/fragmenting of elastin in arterial walls (pulls in Ca2+) > atherosclerosis b. Younger i. Tissues heal faster, ↓ scars (none in fetus) ii. ↑ nutritional state, blood supply, metabolic rate iii. ↑ cell division c. Definitions i. Adhesions: abnormal joining of tissue, common in abdomen, site of infection, scar tissue (may require adhesiotomy) ii. Metaplasia: change in form – smokers pseudostratified ciliated columnar epithelium > stratified squamous epithelium 1. Unable to remove mucus, no cilia > smoker’s cough iii. Hypertrophy: growth of tissue (ms size increases, but # of ms cells stay the same) iv. Atrophy: wasting or loss of tissue (result of “detraining”, often seen in geriatric population) v. Hyperplasia: increase # of cells (ie.) – does not occur in human ms cells (only cats & rats) vi. Neoplasia: new tissue growth (tumor)