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Chapter 6

Classification of Tissues

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Tissues are:Group of cells similar in structure an functionTissues are organized into organsHistology = study of tissues

The four tissue types are:EpithelialConnectiveMuscularNervous

Tissues and tissue types

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Physical protectionSecretion Sensory perceptionAbsorptionFiltrationExcretion

Functions of epithelium

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Includes glands and epitheliumGlands are secretory

AvascularPolarityRegenerationCellularitySupported by connective tissue

Attached to a basement membrane

Epithelial tissue

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Amorphous substance. Divided in 2 layers:

Lamina lucida (basal) Secreted by the epithelium

Lamina densa (reticular)Secreted by the connective tissue

Basement Membrane

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Ciliated MicrovilliStereociliaFlagella

Specializations of epithelium

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Number of cell layersSimpleStratified

Shape of apical surface cellsSquamousCuboidalColumnar

Classification of epithelia

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Cuboidal Epithelia

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Cuboidal Epithelia

Figure 4.4b

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Transitional Epithelium

Figure 4.4c

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Columnar Epithelia

Figure 4.5a

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Columnar Epithelia

Figure 4.5b

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Columnar Epithelia

Figure 4.5c

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Epithelium that secrete substancesExocrine glands

Secrete through ducts onto the surface of the gland

Endocrine glandsRelease hormones into surrounding fluid.

Ductless glands.

Glandular epithelia

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Part 2

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Connective Tissues

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ProtectsSupportsBind tissues together

Classification:Embryonic

MesenchimeLoose connective tissue, mucous

Adult

Connective tissue functions and classification:

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A Classification of Adult Connective Tissues

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No free surfaceVascular

Scanty in tendonsExcept cartilage

Supports the bodyMaintain body form

Connective tissues characteristics

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1)Extracellular matrixGround substance

AmorphousBinds cells to fibersColorless HomogeneousLiquid, semisolid, gel-like, or hard

Components of the connective tissue

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Matrix

FibersCollagen (white)

Most abundantBrings flexibility and strength to the

tissueThicker one

Elastic (yellow)Brings elasticity to the tissuesCan stretch and recoil

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ReticularThinnest oneFound in smooth muscle and framework of the

organsBrings flexibility to organs that need changes

in volume

Fibers

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2) CellsFibroblast

most abundantSynthesis of fibers and ground substance

MacrophagePhagocytic capacity

Components of the connective tissue

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AdipocytesClosely packedSignet ring cellNucleus eccentric and flatMesenchymal cells

Mast cellsReleases histaminResponsible for allergic reactions

Lymphocytes, etc

Components of the connective tissue

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The Cells and Fibers of Connective Tissue Proper

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Classified as loose or denseLooseAreolar tissueAdipose tissueReticular tissueRich blood supply

Connective tissue proper

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Connective tissue proper

DenseDense regular Dense irregular Elastic Poor blood supply

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Connective Tissue in Embryos

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Dense Connective Tissues

Figure 4.12a

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Dense Connective Tissues

Figure 4.12b

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Dense Connective Tissues

Figure 4.12c

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Has osteocytes and osteoblastsLacunaLittle ground substanceDense mineralized matrixRichly Vascularized

Bone, or osseous tissue

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Bone

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Part 3

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Supporting connective tissues: Cartilage

Cells called chondrocytes or chondroblasts

Cells found in lacunaeFirm matrixAvascularThree types: hyaline, elastic,

fibrocartilage

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Types of Cartilage

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Types of Cartilage

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Types of Cartilage

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• Blood– Red blood cells, white blood cells and

platelets– Plasma is the fluid matrix

Fluid connective tissues

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Formed Elements of the Blood

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Specialized for contractionThree types

SkeletalCardiacSmooth

Muscle tissue

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Cells are multinucleate, long, cylindricalPresence of striation Voluntary muscle

Skeletal muscle

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Muscle Tissue - Skeletal

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Cells: Long,1 or 2 nucleusBranching cells

Intercalated discsPresence of striationInvoluntary muscle

Cardiac muscle

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Muscle Tissue - Cardiac

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CellsFusiformOne central nucleus

Non-striated Involuntary muscleForms the wall of hollow organs

Smooth muscle tissue

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Muscle Tissue - Smooth

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Nervous Tissue

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NeuronsTransmits impulsesNo intercellular matrix

NeurogliaSupport, protects and insulates the

nervous tissueGreater number

Neural tissue cells

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BrainSpinal cordNerves

Neural tissue location

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