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Human Physiology:Tissues
Source: Collected from different sources on the
internet-http://koning.ecsu.ctstateu.edu/cell/cell.html
BYDR BOOMINATHAN Ph.D. M.Sc.,(Med. Bio, JIPMER), M.Sc.,(FGSWI,
Israel), Ph.D (NUS, SINGAPORE)PONDICHERRY UNIVERSITYIII
Lecture7/August/2012Collected, and modified by Dr Boominathan
Ph.D.
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Human Physiology:Levels Of Organization and Function-Organelles,
tissues, organs and systems
Source: Collected from different sources on the
internet-http://koning.ecsu.ctstateu.edu/cell/cell.htmlCollected
and modified by Dr Boominathan Ph.D. BYDR BOOMINATHAN Ph.D.
M.Sc.,(Med. Bio, JIPMER), M.Sc.,(FGSWI, Israel), Ph.D (NUS,
SINGAPORE)PONDICHERRY UNIVERSITYII Lecture7/August/2012
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Tissues
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TissuesDefinition: a group of closely associated cells that
perform related functions and are similar in structureBetween
cells: nonliving extracellular materialFour basic types of
tissuefunctionEpitheliumcoveringConnective tissuesupportMuscle
tissuemovementNervous tissuecontrol
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Epithelia (plural)Epithelium: sheet of cells that covers a body
surface or lines a body cavity; also form most of the bodys
glandsRoles: as interfaces and as boundariesFunctions:Protection
AbsorptionSensory reception Ion transportSecretion Filtration
Formation of slippery surfaces for movement
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Special characteristics of epitheliaCellularitySpecialized
contactsPolarityFree upper (apical) surfaceLower (basal) surface
contributing basal lamina to basement membrane Support by
connective tissue Avascular but innervatedWithout vesselsWith nerve
endings Regeneration
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Classification of epitheliaAccording to thicknesssimple - one
cell layerstratified more than one layer of cells (which are named
according to the shape of the cells in the apical layer)According
to shapesquamous wider than tallcuboidal as tall as widecolumnar -
taller than wide
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to protect
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where diffusion is importantwhere tissues are involved in
secretion and absorption: larger cells because of the machinery of
production, packaging, and energy requirements
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ciliated literally = eyelashes(see next page)
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Stratified: regenerate from below
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Rare
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Rare
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Endothelium A simple squamous epithelium that lines the interior
of the circulatory vessels and heartMesothelium
Simple squamous epithelium that lines the peritoneal, pleural
and pericardial cavities and covers the viscera
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GlandsEpithelial cells form themProduction & secretion of
needed substancesAre aqueous (water-based) productsThe protein
product is made in rough ER, packed into secretory granules by
Golgi apparatus, released from the cell by exocytosis
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Classification of glandsBy where they release their
productExocrine: external secretion onto body surfaces (skin) or
into body cavitiesEndocrine: secrete messenger molecules (hormones)
which are carried by blood to target organs; ductless glandsBy
whether they are unicellular or multicellular
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Exocrine glandsunicellular or multicellularUnicellular: goblet
cell scattered within epithelial lining of intestines
andrespiratory tubes
Product: mucinmucus is mucin & water
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Multicellular exocrine glands
Epithelium-walledduct and asecretory unit
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Examples of exocrine gland productsMany types of mucus secreting
glandsSweat glands of skinOil glands of skinSalivary glands of
mouthLiver (bile)Pancreas (digestive enzymes)Mammary glands
(milk)
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Endocrine glandsDuctless glands
Release hormones into extracellular spaceHormones are messenger
molecules
Hormones enter blood and travel to specific target organs
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Epithelial surface featuresLateral surfaceAdhesion
proteinsTongue and groove wavy contoursCell junctions: see next
slideBasal surfaceBasal lamina: noncellular sheet of protein
together with reticular fibers form basement membraneApical
surface
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Cell JunctionsTight junctionsSo close that are sometimes
impermeableAdherens junctionsTransmembrane linker
proteinsDesmosomesAnchoring junctionsFilaments anchor to the
opposite sideGap junctionsAllow small molecules to move between
cells
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Apical surface featuresMicrovilli maximize surface
areaFingerlike extensions of the plasma membrane of apical
epithelial cellsOn moist and mucus secreting epitheliumLongest on
epithelia that absorb nutrients (small intestine) or transport ions
(kidneys)
(continued)
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CiliaWhiplike motile extentions of the apical surface
membranesFlagellumLong isolated ciliumOnly found as sperm in
human
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Four basic types of tissue
EpitheliumConnective tissueConnective tissue proper (examples:
fat tissue, fibrous tissue of ligaments)CartilageBoneBloodMuscle
tissueNervous tissue
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Classes of Connective Tissue: note the cell types and great
variety of subclasses
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Connective TissueOriginate from embryonic tissue called
mesenchymeMost diverse and abundant type of tissueMany subclasses
(see previous slide)Function: to protect, support and bind together
other tissuesBones, ligaments, tendonsAreolar cushions; adipose
insulates and is food sourceBlood cells replenished; body tissues
repairedCells separated from one another by large amount of
nonliving extracellular matrix
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Extracellular Matrix explainedNonliving material between
cellsProduced by the cells and then extrudedResponsible for the
strengthTwo componentsGround substanceOf fluid, adhesion proteins,
proteoglycansLiquid, semisolid, gel-like or very hard Fibers:
collagen, elastic or reticular
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Basic functions of connective tissue reviewedSupport and binding
of other tissuesHolding body fluidsDefending the body against
infectionmacrophages, plasma cells, mast cells, WBCsStoring
nutrients as fat
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Classes of Connective Tissue*
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*Classes of Connective Tissue
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*Classes of Connective Tissue
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Classes of Connective Tissue*
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Classes of Connective Tissue*
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Membranes that combine epithelial sheets plus underlying
connective tissue proper (see next slide) Cutaneous membranesSkin:
epidermis and dermisMucous membranes, or mucosaLines every hollow
internal organ that opens to the outside of the bodySerous
membranes, or serosaSlippery membranes lining the pleural,
pericardial and peritoneal cavitiesThe fluid formed on the surfaces
is called a transudateSynovial membranesLine joints
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Cutaneous membrane
Mucous membrane
Serous membrane
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Four basic types of tissue
EpitheliumConnective tissueMuscle
tissueSkeletalCardiacSmoothNervous tissue
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Four basic types of tissue
EpitheliumConnective tissueMuscle tissueNervous
tissueNeuronsSupporting cells
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Tissue response to injuryImmune: takes longer and is highly
specificInflammationNonspecific, local, rapidInflammatory
chemicalsSigns: heat, swelling, redness, painRepair two
waysRegenerationFibrosis and scarringSevere injuriesCardiac and
nervous tissue
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Tumors (neoplasms): abnormal growth of cellsAdenoma neoplasm of
glandular epithelium, benign or malignantCarcinoma cancer arising
in an epithelium (90% of all human cancers)Sarcoma cancer arising
in mesenchyme-derived tissue (connective tissues and muscle)