Everything you need to know about histology, Summaries of Histology

Download Everything you need to know about histology and more Summaries Histology in PDF only on Docsity! ha naa TOU Ms Histology Four Types of Tissues • Tissues are collections of cells and cell products that perform specific, limited functions Epithelial Tissues • Functions of Epithelial Tissue • Provide physical protection • Control permeability • Provide sensation • Produce specialized secretions (glandular epithelium) Intercellular Connections • Support and Communication • CAMs (cell adhesion molecules): • Transmembrane proteins • Intercellular cement: • Proteoglycans • Hyaluronan (hyaluronic acid): • Glycosaminoglycans Intercellular Connections • Cell junctions • Form bonds with other cells or extracellular material: • Occluding (tight) junctions • Gap junctions • Macula adherens (desmosomes) Intercellular Connections — TCS TU Eel oxo) aTateted fede ls Adhesion belt Cytoskeleton (actin filaments) Spot desmosome z> Cell adhesion molecules (CAMs) re -_ Intercellular _ | [- * cement (d) Spot desmosome  Adhesion belt Cytoskeleton (actin filaments) Spot desmosome membrane Ce) Hemideoesrmmosome  g apparatus Nucleus Basement a? membrane | a Mitochondria bs,  TABLE 4-1 Classifying Epithelia Simple | SQUAMOUS CUBOIDAL _ _Ddelejee COLUMNAR Simple squamous epithelium Simple cuboidal epithelium Stratified Stratified squamous epithelium Stratified cuboidal epithelium Stratified columnar epithelium  SIMPLE SQUAMOUS EPITHELIUM LOCATIONS: Epithelia lining ventral body cavities; lining heart and blood vessels; portions of kidney tubules (thin sections of nephron loops), == inner lining of cornea; alveoll = <4 (ait sacs) of lungs FUNCTIONS: Reduces friction; controls vessel i permeability; performs dl absorption and secretion —Connectve tissue LM x 238 (a) Lining of peritoneal cavity  SIMPLE CUBOIDAL EPITHELIUM LOCATIONS: Glands; ducts; portions of kidney tubules; thyroid gland FUNCTIONS: Limited protection, secretion, absorption Fame Basement a membrane LON bd ee aii d (b) Kidney tubule LM x 1426  LOCATIONS: Lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract FUNCTIONS: Protection,» i/ secretion ha : , e Te % Basement—e sep 3 R membrane \ Wy by ° . bo e wr 2( e; Loos! soa ag aq @a ' 4 oe A eae [b) Trachea IM x 394  TRANSITIONAL EPITHELIUM LOCATIONS: Urinary bladder; renal pelvis of kidneys; ureters 2 “A an _{ q be bt Me FUNCTIONS: Permits ie) expansion and recoil Epithelium a) 4 8 after stretching relaxed) 6 fad OG ‘aa 0 4948 Basement ‘ (hy i! (, iM at membrane ——— "Te * an 2a Connective—.."\" jo” <7 , EMPTY BLADDER _ tissue and smooth CM x 394 <= muscle layers . ene?! ¢ | Epithelium Wee 4 ¢ a ove! 06) @;| (stretched) |, F500 Sae= ae Basement ==" ee g membrane |e a FULL BLADDER “connective tissue and LM x 454 (c) Urinary bladder smooth muscle layers Glandular Epithelia • Endocrine Glands • Release hormones: • Into interstitial fluid • No ducts • Exocrine Glands • Produce secretions: • Onto epithelial surfaces • Through ducts Mechanisms of Glandular Secretion Glandular Epithelia • Types of Secretions • Serous glands: • Watery secretions • Mucous glands: • Secrete mucins • Mixed exocrine glands: • Both serous and mucous lassification of Exocrine Glands TABLE 4-2 A Classification of Exocrine Glands FEATURE DESCRIPTION SECRETION MECHANISM Merocrine Secretion occurs through exocytosis, Apocrine Secretion occurs through loss of cytoplasm containing secretory product. Holocrine Secretion occurs through loss of entire cell containing secretory product, SECRETION TYPE Serous Watery solution containing enzymes Mucous Thick, slippery mucus Mixed Contains more than one type of secretion EXAMPLES Saliva from salivary glands; mucus in digestive and respiratory tracts; perspiration on the skin; milk in breasts Milk in breasts; viscous underarm perspiration Skin oils and waxy coating of hair (produced by sebaceous glands of the skin) Secretions of parotid salivary gland Secretions of sublingual salivary gland Secretions of submandibular salivary gland (serous and mucous) Connective Tissues • Characteristics of Connective Tissues • Specialized cells • Solid extracellular protein fibers • Fluid extracellular ground substance • The extracellular components of connective tissues (fibers and ground substance) make up the matrix • Majority of tissue volume • Determines specialized function Connective Tissues • Cell Types of Connective Tissue Proper • Fibroblasts • Macrophages • Adipocytes • Mast cells Connective Tissues • Connective Tissue Fibers • Collagen fibers • Reticular fibers • Elastic fibers Connective Tissues • Ground Substance • Is clear, colorless, and viscous • Fills spaces between cells and slows pathogen movement LOOSE CONNECTIVE TISSUE LOCATIONS: Beneath dermis of skin, digestive tract, respiratory and urinary tracts; between muscles; around blood vessels, nerves, and around joints FUNCTIONS: Cushions Aan organs; provides support fy \ but permits independent =) | movement; nhagocytic bs i cells provide defense i against pathogens Collagen fibers Fat cell | Ai Fibroblasts Elastic fib I Ve sine at Ne or Nlacrophage a . (a) Loose connective tissue ADIPOSE TISSUE LOCATIONS: Deep to the skin, especially at sides, buttocks, breasts; padding around eyes and kidneys FUNCTIONS: Provides padding and cushions shocks; insulates (reduces heat loss); stores energy reserves (b) Adipose tissue Ive Tissue Proper LOCATIONS: Between iy skeletal muscles and “HAIN | skeleton (tendons); between WHINY HN bones (ligaments); covering N si Colla ae Obi aren) skeletal muscles; capsules yp, ‘fibers ie of internal organs N\\ ani FUNCTIONS: Provides firm i attachment; conducts pull of ! muscles; reduces friction between © muscles; stabilizes relative positions of bones: helps prevent overexpansion a of organs (such asthe urinary bladder) _‘(¢) Tendon Supportive Connective Tissues • Cartilage Matrix • Proteoglycans derived from chondroitin sulfates • Ground substance proteins • Chondrocytes (cartilage cells) surrounded by lacunae (chambers) Supportive Connective Tissues • Cartilage Structure • No blood vessels: • Chondrocytes produce antiangiogenesis factor • Perichondrium: • Outer, fibrous layer (for strength) • Inner, cellular layer (for growth and maintenance) Supportive Connective Tissues • Types of Cartilage • Hyaline cartilage: • Stiff, flexible support • Reduces friction between bones • Found in synovial joints, rib tips, sternum, and trachea • Elastic cartilage: • Supportive but bends easily • Found in external ear and epiglottis • Fibrous cartilage (fibrocartilage): • Limits movement • Prevents bone-to-bone contact • Pads knee joints • Found between pubic bones and intervertebral discs FIBROUS CARTILAGE LOCATIONS: Pads Ul LAI. oe mea within knee joint; Lb pgp) ‘al Pee if between pubic ; r\ PLL ET ee bones of pelvis; Ce 7 Collagen ae ae intervertebral discs LA ff A. ‘bers | all | FUNCTIONS: Resists Ay Po NN < compression; AG [ (ee ORE: 4 prevents bone-to-bone Cfipk \y Chondrocyte Va wna contact; limits relative movement Uff in lacuna JS “il i J Le ~~ Ma (c) Fibrous cartilage LM x 1000 Supportive Connective Tissues • Bone or osseous tissue • Strong (calcified: calcium salt deposits) • Resists shattering (flexible collagen fibers) • Bone cells or osteocytes • Arranged around central canals within matrix • Small channels through matrix (canaliculi) access blood supply • Periosteum • Covers bone surfaces • Fibrous layer • Cellular layer 7 camel | : a ca IN) é, A i My Nah 3 bas flt ea Osteocytes : SU Zs MMe Gt i 2 Bee in lacunae aN a ~ PERIOSTEUM Fibrous layer Cellular layer et ee Pee Aan SS ie Central yA RS OG AT Sh Matrix — a: | ti ue ee Ns No =| Blood vessels SBN’ Membranes • Four Types of Membranes • Mucous membranes • Serous membranes • Cutaneous membrane • Synovial membranes Mucous secretion Epithelium 30. Go -_ Lamina propria ia) Mucous membrane _ (loose connective tissue) Serous fluid Epithelium —+ Loose connective tissue [ ; - Loose connective tissue ——— = (b) Serous membrane Epithelium Dense irregular (c) Cutaneous membrane Connective tissue (Hyaline) articular cartilage Synovial fluid Capsule Capillary Adipocytes Loose connective tissue Epithelium Synovial membrane fe Bone (d) Synovial membrane Membranes • Mucous Membranes (Mucosae) • Line passageways that have external connections • In digestive, respiratory, urinary, and reproductive tracts • Epithelial surfaces must be moist: • To reduce friction • To facilitate absorption and excretion • Lamina propria: • Is areolar tissue Membranes Mucous secretion — Epithelium Oo — Lamina propria (loose connective tissue) (a) Mucous membrane Serous fluid “a Epithelium L Loose connective tissue (b) Serous membrane Membranes • Cutaneous Membrane • Is skin, surface of the body • Thick, waterproof, and dry • Synovial Membranes • Line moving, articulating joint cavities • Produce synovial fluid (lubricant) • Protect the ends of bones • Lack a true epithelium I Epithelium KF Loose connective tissue —— ee + Dense irregular (c) Cutaneous membrane Connective tissue (Hyaline) articular cartilage Synovial fluid Capsule Capillary Adipocytes WL Loose connective fH) tissue Synovial pt Epithelium membrane 7 | Bone (d) Synovial membrane  CARDIAC MUSCLE TISSUE Cells are short, branched, and striated, Pn usually with a single nucleus; cells are | i Tt | interconnected by intercalated discs. Mecces | | i), i ‘i LOCATION: Heart ("ry | Nucleus ot —_ B FUNCTIONS: Circulates : | |) aos — Cardiac blood; maintains blood iil muscle (hydrostatic) pressure a f Ledeen Intercelated TPM ye discs We l NN iy i il a i ill ! OU stitions ie (b) Cardiac muscle LM x 450  SMOOTH MUSCLE TISSUE Cells are short, spindle-shaped, and : a pe ae nonstriated, with a single, central nucleus : oe eae LOCATIONS: Found in 2 _o_ ae es the walls of blood vessels r Lx ep and in digestive, respiratory, == ae ‘= urinary, and reproductive organs aos muscle = ee FUNCTIONS: Moves food, es wl =e ad urine, and reproductive eee — ca tract secretions; controls a = = diameter of respiratory x 4 as Be Ce aa passageways; regulates y i ae | ciametr of blood vessels t = ee (c) Smooth muscle LM x 235 Neural Tissue • Also called nervous or nerve tissue • Specialized for conducting electrical impulses • Rapidly senses internal or external environment • Processes information and controls responses Neural Tissue • Cell Parts of a Neuron • Cell body: • Contains the nucleus and nucleolus • Dendrites: • Short branches extending from the cell body • Receive incoming signals • Axon (nerve fiber): • Long, thin extension of the cell body • Carries outgoing electrical signals to their Nuclei of ) Cell body Aa \y,neurogla AY aD \ , Nucleus | ofneuron Spinal Cell . é Saar cord body uy, ) Axon" Oe \ | / 71k * Dendrites eh YS a LM x 600 (a) Neuron (b) Photomicrograph of neuron cell body Tissue Injuries and Repair • Tissues respond to injuries to maintain homeostasis • Cells restore homeostasis with two processes: • Inflammation • Regeneration Aging and Tissue Structure • Speed and efficiency of tissue repair decrease with age due to • Slower rate of energy consumption (metabolism) • Hormonal alterations • Reduced physical activity Aging and Cancer Incidence • Cancer rates increase with age • 1 in 4 people in the United States develops cancer • Cancer is the #2 cause of death in the United States • Environmental chemicals and cigarette smoke cause cancer