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.

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

Tissues

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

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

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

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

to protect

where diffusion is importantwhere tissues are involved in secretion and absorption: larger cells because of the machinery of production, packaging, and energy requirements

ciliated literally = eyelashes(see next page)

Stratified: regenerate from below

Rare

Rare

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

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

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

Exocrine glandsunicellular or multicellularUnicellular: goblet cell scattered within epithelial lining of intestines andrespiratory tubes

Product: mucinmucus is mucin & water

Multicellular exocrine glands

Epithelium-walledduct and asecretory unit

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)

Endocrine glandsDuctless glands

Release hormones into extracellular spaceHormones are messenger molecules

Hormones enter blood and travel to specific target organs

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

Cell JunctionsTight junctionsSo close that are sometimes impermeableAdherens junctionsTransmembrane linker proteinsDesmosomesAnchoring junctionsFilaments anchor to the opposite sideGap junctionsAllow small molecules to move between cells

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)

CiliaWhiplike motile extentions of the apical surface membranesFlagellumLong isolated ciliumOnly found as sperm in human

Four basic types of tissue

EpitheliumConnective tissueConnective tissue proper (examples: fat tissue, fibrous tissue of ligaments)CartilageBoneBloodMuscle tissueNervous tissue

Classes of Connective Tissue: note the cell types and great variety of subclasses

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

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

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

Classes of Connective Tissue*

*Classes of Connective Tissue

*Classes of Connective Tissue

Classes of Connective Tissue*

Classes of Connective Tissue*

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

Cutaneous membrane

Mucous membrane

Serous membrane

Four basic types of tissue

EpitheliumConnective tissueMuscle tissueSkeletalCardiacSmoothNervous tissue

Four basic types of tissue

EpitheliumConnective tissueMuscle tissueNervous tissueNeuronsSupporting cells

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

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)