Chapter 5: The Integumentary System. The structures and functions of the integumentary system.
Chapter 5: Integumentary System
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Transcript of Chapter 5: Integumentary System
Chapter 5:Tissues
(The Living Fabric)
The four primary tissue classes…. we shall see examples of all of these types.
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Overview of four tissue types: epithelial, connective, muscle, and nervous tissues.
Nervous tissue: Internal communication• Brain, spinal cord, and nerves
Muscle tissue: Contracts to cause movement• Muscles attached to bones (skeletal)• Muscles of heart (cardiac)• Muscles of walls of hollow organs (smooth)
Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters• Skin surface (epidermis)• Lining of GI tract organs and other hollow organs
Connective tissue: Supports, protects, bindsother tissues together• Bones• Tendons• Fat and other soft padding tissue
Dr. Edward Zirm First Corneal Transplant
1906
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Classification of epithelia.
Squamous
Cuboidal
Columnar(b) Classification based on cell shape.
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Classification of epithelia.
Stratified
Simple
Apical surface
Basal surface
Apical surface
Basal surface
(a) Classification based on number of cell layers.
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(a) Classes of epithelium
(b) Cell shapes
Simple Pseudostratifiedcolumnar
Stratified
Squamous Cuboidal Columnar
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Longitudinal sections
Cross sections
Oblique sections
The various planes of space through which a tissue or organ may be sliced will change the perspective of the view of the structures.
This is important clinically with regard to MRI and Cat Scan assessments.
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Epithelial tissues.
(a) Simple squamous epithelium
Description: Single layer of flattenedcells with disc-shaped central nucleiand sparse cytoplasm; the simplestof the epithelia.
Function: Allows passage ofmaterials by diffusion and filtrationin sites where protection is notimportant; secretes lubricatingsubstances in serosae.
Location: Kidney glomeruli; air sacsof lungs; lining of heart, bloodvessels, and lymphatic vessels; liningof ventral body cavity (serosae).
Photomicrograph: Simple squamous epitheliumforming part of the alveolar (air sac) walls (125x).
Air sacs oflung tissue
Nuclei ofsquamousepithelialcells
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Epithelial tissues.
(b) Simple cuboidal epitheliumDescription: Single layer ofcubelike cells with large,spherical central nuclei.
Function: Secretion andabsorption.
Location: Kidney tubules;ducts and secretory portionsof small glands; ovary surface.
Photomicrograph: Simple cuboidalepithelium in kidney tubules (430x).
Basementmembrane
Connectivetissue
Simplecuboidalepithelialcells
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Epithelial tissues.
(c) Simple columnar epitheliumDescription: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells).
Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action.Location: Nonciliated type lines most of the digestive tract (stomach to anal canal),gallbladder, and excretory ducts of someglands; ciliated variety lines small bronchi, uterine tubes, and some regionsof the uterus.
Photomicrograph: Simple columnar epitheliumof the stomach mucosa (860X).
Simplecolumnarepithelialcell
Basementmembrane
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Epithelial tissues.
(d) Pseudostratified columnar epithelium
Description: Single layer of cells ofdiffering heights, some not reachingthe free surface; nuclei seen atdifferent levels; may contain mucus-secreting cells and bear cilia.
Function: Secretion, particularly ofmucus; propulsion of mucus byciliary action.
Location: Nonciliated type in male’ssperm-carrying ducts and ducts oflarge glands; ciliated variety linesthe trachea, most of the upperrespiratory tract.
Photomicrograph: Pseudostratified ciliatedcolumnar epithelium lining the human trachea (570x).
Trachea
Cilia
Pseudo-stratifiedepitheliallayer
Basementmembrane
Mucus ofmucous cell
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Epithelial tissues.
(e) Stratified squamous epithelium
Description: Thick membranecomposed of several cell layers;basal cells are cuboidal or columnarand metabolically active; surfacecells are flattened (squamous); in thekeratinized type, the surface cells arefull of keratin and dead; basal cellsare active in mitosis and produce thecells of the more superficial layers.
Function: Protects underlyingtissues in areas subjected to abrasion.
Location: Nonkeratinized type formsthe moist linings of the esophagus,mouth, and vagina; keratinized varietyforms the epidermis of the skin, a drymembrane.
Photomicrograph: Stratified squamous epitheliumlining the esophagus (285x).
Stratifiedsquamousepithelium
NucleiBasementmembrane
Connectivetissue
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Epithelial tissues.
(f) Transitional epitheliumDescription: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells domeshaped or squamouslike, depending on degree of organ stretch.
Function: Stretches readily and permits distension of urinary organ by contained urine.Location: Lines the ureters, urinary bladder, and part of the urethra.
Photomicrograph: Transitional epithelium lining the urinary bladder, relaxed state (360X); note the bulbous, or rounded, appearance of the cells at the surface; these cells flatten and become elongated when the bladder is filled with urine.
BasementmembraneConnectivetissue
Transitionalepithelium
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Types of multicellular exocrine glands.
Compound duct structure(duct branches)
Simple tubular
ExampleIntestinal glands
Simple branchedtubularExampleStomach (gastric)glands
Compound tubularExampleDuodenal glands of small intestine
Compound alveolarExampleMammary glands
SimplealveolarExampleNo importantexample in humans
Simple branchedalveolarExampleSebaceous (oil)glands
CompoundtubuloalveolarExampleSalivary glands
Tubularsecretorystructure
Alveolarsecretorystructure
Surface epithelium Duct Secretory epithelium
Simple duct structure(duct does not branch)
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Chief modes of secretion in human exocrine glands.
Secretorycell fragments
(b) In holocrine glands, the entire secretory cell ruptures, releasing secretions and dead cell fragments.
(a) Merocrine glands secrete their products by exocytosis.
Secretoryvesicles
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Connective tissues.
(a) Connective tissue proper: loose connective tissue, areolar
Description: Gel-like matrix with allthree fiber types; cells: fibroblasts,macrophages, mast cells, and somewhite blood cells.
Function: Wraps and cushionsorgans; its macrophages phagocytizebacteria; plays important role ininflammation; holds and conveystissue fluid.
Location: Widely distributed underepithelia of body, e.g., forms laminapropria of mucous membranes;packages organs; surroundscapillaries.
Photomicrograph: Areolar connective tissue, asoft packaging tissue of the body (300x).
Epithelium
Laminapropria
Fibroblastnuclei
Elasticfibers
Collagenfibers
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Connective tissues.
(b) Connective tissue proper: loose connective tissue, adipose
Description: Matrix as in areolar,but very sparse; closely packedadipocytes, or fat cells, havenucleus pushed to the side by largefat droplet.
Function: Provides reserve foodfuel; insulates against heat loss;supports and protects organs.
Location: Under skin in thehypodermis; around kidneys andeyeballs; within abdomen; in breasts.
Photomicrograph: Adipose tissue from thesubcutaneous layer under the skin (350x).
Nucleus offat cell
Vacuolecontainingfat droplet
Adiposetissue
Mammaryglands
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Connective tissues.
(c) Connective tissue proper: loose connective tissue, reticular
Description: Network of reticularfibers in a typical loose groundsubstance; reticular cells lie on thenetwork.
Function: Fibers form a soft internalskeleton (stroma) that supports othercell types including white blood cells,mast cells, and macrophages.
Location: Lymphoid organs (lymphnodes, bone marrow, and spleen).
Photomicrograph: Dark-staining network of reticularconnective tissue fibers forming the internal skeletonof the spleen (350x).
Spleen
White bloodcell(lymphocyte)
Reticularfibers
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Connective tissues.
(d) Connective tissue proper: dense connective tissue, dense regular
Description: Primarily parallelcollagen fibers; a few elastic fibers;major cell type is the fibroblast.
Function: Attaches muscles tobones or to muscles; attaches bonesto bones; withstands great tensilestress when pulling force is appliedin one direction.
Location: Tendons, mostligaments, aponeuroses.
Photomicrograph: Dense regular connectivetissue from a tendon (500x).
Shoulderjoint
Ligament
Tendon
Collagenfibers
Nuclei offibroblasts
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Connective tissues.
(e) Connective tissue proper: dense connective tissue, dense irregular Description: Primarilyirregularly arranged collagenfibers; some elastic fibers;major cell type is the fibroblast.
Function: Able to withstandtension exerted in manydirections; provides structuralstrength.
Location: Fibrous capsules oforgans and of joints; dermis ofthe skin; submucosa ofdigestive tract.
Photomicrograph: Dense irregularconnective tissue from the dermis of theskin (400x).
Collagenfibers
Nuclei offibroblasts
Fibrousjointcapsule
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Connective tissues.
(f) Connective tissue proper: dense connective tissue, elastic
Description: Dense regularconnective tissue containing a highproportion of elastic fibers.
Function: Allows recoil of tissuefollowing stretching; maintainspulsatile flow of blood througharteries; aids passive recoil of lungsfollowing inspiration.
Location: Walls of large arteries;within certain ligaments associatedwith the vertebral column; within thewalls of the bronchial tubes.
Elastic fibers
Aorta
HeartPhotomicrograph: Elastic connective tissue inthe wall of the aorta (250x).
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Connective tissues.
(g) Cartilage: hyaline
Description: Amorphous but firmmatrix; collagen fibers form animperceptible network; chondroblastsproduce the matrix and when mature(chondrocytes) lie in lacunae.
Function: Supports and reinforces;has resilient cushioning properties;resists compressive stress.
Location: Forms most of theembryonic skeleton; covers the endsof long bones in joint cavities; formscostal cartilages of the ribs; cartilagesof the nose, trachea, and larynx.
Photomicrograph: Hyaline cartilage from thetrachea (750x).
Costalcartilages
Chondrocytein lacuna
Matrix
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Connective tissues.
(h) Cartilage: elasticDescription: Similar to hyalinecartilage, but more elastic fibersin matrix.
Function: Maintains the shapeof a structure while allowinggreat flexibility.
Location: Supports the externalear (pinna); epiglottis.
Photomicrograph: Elastic cartilage fromthe human ear pinna; forms the flexibleskeleton of the ear (800x).
Chondrocytein lacuna
Matrix
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Connective tissues.
(i) Cartilage: fibrocartilageDescription: Matrix similar tobut less firm than that in hyalinecartilage; thick collagen fiberspredominate.
Function: Tensile strengthwith the ability to absorbcompressive shock.
Location: Intervertebral discs;pubic symphysis; discs of kneejoint.
Photomicrograph: Fibrocartilage of anintervertebral disc (125x). Special stainingproduced the blue color seen.
Intervertebraldiscs
Chondrocytesin lacunae
Collagenfiber
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Connective tissues.
(j) Others: bone (osseous tissue)Description: Hard, calcifiedmatrix containing many collagenfibers; osteocytes lie in lacunae.Very well vascularized.
Function: Bone supports andprotects (by enclosing);provides levers for the musclesto act on; stores calcium andother minerals and fat; marrowinside bones is the site for bloodcell formation (hematopoiesis).
Location: Bones
Photomicrograph: Cross-sectional viewof bone (125x).
Lacunae
Lamella
Centralcanal
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Connective tissues.
(k) Others: bloodDescription: Red and whiteblood cells in a fluid matrix(plasma).
Function: Transport ofrespiratory gases, nutrients,wastes, and other substances.
Location: Contained withinblood vessels.
Photomicrograph: Smear of human blood (1860x); twowhite blood cells (neutrophil in upper left and lymphocytein lower right) are seen surrounded by red blood cells.
Neutrophil
Red bloodcells
Lymphocyte
Plasma
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Nervous tissue.
Photomicrograph: Neurons (350x)
Function: Transmit electricalsignals from sensory receptorsand to effectors (muscles andglands) which control their activity.
Location: Brain, spinalcord, and nerves.
Description: Neurons arebranching cells; cell processesthat may be quite long extend fromthe nucleus-containing cell body;also contributing to nervous tissueare nonirritable supporting cells(not illustrated).
Dendrites
Neuron processes Cell body
Axon
Nuclei ofsupportingcells
Cell bodyof a neuron
Neuronprocesses
Nervous tissue
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Muscle tissues.
(a) Skeletal muscleDescription: Long, cylindrical,multinucleate cells; obviousstriations.
Function: Voluntary movement;locomotion; manipulation of theenvironment; facial expression;voluntary control.
Location: In skeletal musclesattached to bones oroccasionally to skin.
Photomicrograph: Skeletal muscle (approx. 460x).Notice the obvious banding pattern and thefact that these large cells are multinucleate.
Nuclei
Striations
Part ofmuscle fiber (cell)
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Muscle tissues.
(b) Cardiac muscleDescription: Branching, striated, generally uninucleate cells that interdigitate atspecialized junctions (intercalated discs).
Function: As it contracts, it propels blood into the circulation; involuntary control.Location: The walls of the heart.
Photomicrograph: Cardiac muscle (500X);notice the striations, branching of cells, andthe intercalated discs.
Intercalateddiscs
Striations
Nucleus
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(c) Smooth muscleDescription: Spindle-shapedcells with central nuclei; nostriations; cells arranged closely to form sheets.
Function: Propels substancesor objects (foodstuffs, urine,a baby) along internal passage-ways; involuntary control.
Location: Mostly in the wallsof hollow organs.
Photomicrograph: Sheet of smooth muscle (200x).
Smoothmusclecell
Nuclei
Muscle tissues.
Intercellular space
Plasma membrane
Cell-adhesion proteins
(a) Tight junction
Intercellular space
Cell-adhesionproteinsPlaqueIntermediatefilaments ofcytoskeleton
(b) Desmosome
Proteins
Connexon
Pore
(c) Gap junction Basement membrane (d) Hemidesmosome
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Remember the three junction types previously discussed.
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Classes of membranes.
Cutaneous membrane(skin
Mucosa of nasalcavity
Mucosa of lungbronchi
Mucosa of mouth
Esophagus lining
Parietal pericardiumVisceral pericardium
(a) Cutaneous membrane (the skin) covers the body surface.
(b) Mucous membranes line body cavities open to the exterior.
(c) Serous membranes line body cavities closed to the exterior.
ParietalperitoneumVisceralperitoneum
Parietal pleuraVisceral pleura