Chapter 2 - Biological TissueChapter 2 - Biological Tissue

Each type of tissue has a Each type of tissue has a specialized function and a specialized function and a

distinctive organizationdistinctive organization

Types of TissueTypes of Tissue

Tissue is classified as one of four types:Tissue is classified as one of four types:

EpithelialEpithelial NervousNervous MuscleMuscle Connective (Bone, tendon, ligaments, Connective (Bone, tendon, ligaments,

cartilage)cartilage)

Types of Tissue:EpithelialTypes of Tissue:Epithelial

Lining tissueLining tissue layers of cellslayers of cells subject to wearsubject to wear cells regenerationcells regeneration role in diffusion and role in diffusion and

and bio-electrical and bio-electrical conductionconduction

Type of Tissue: NerveType of Tissue: Nerve

Forms the nervous Forms the nervous system (brain, spinal system (brain, spinal cord etc.) Basic Cell cord etc.) Basic Cell NeuronNeuron CommunicationCommunication IrritabilityIrritability ConductivityConductivity Not load bearingNot load bearing Injured under too much Injured under too much

tension or compressiontension or compression

Type of tissue: MuscleType of tissue: Muscle

Smooth: involuntary Smooth: involuntary and no striationsand no striations

Skeletal: voluntary Skeletal: voluntary and striatedand striated conductivity, conductivity,

extensibility, extensibility, elasticity, contractilityelasticity, contractility

Cardiac: involuntary Cardiac: involuntary and striatedand striated

Type of Tissue: ConnectiveType of Tissue: Connective

Fibers (collagenous, reticular and Fibers (collagenous, reticular and elastic)elastic)

CellsCells Other macromoleculesOther macromolecules

Types of Tissue: ConnectiveTypes of Tissue: Connective

Density & ArrangementDensity & Arrangement Loose (fascia)Loose (fascia) Dense (tendon, lig etc)Dense (tendon, lig etc)

IrregularIrregular RegularRegular

Types of Loose Tissue: Types of Loose Tissue: FibroeslaticFibroeslatic Loose network of Loose network of

fibersfibers Extensible: collagen Extensible: collagen

fibers meshfibers mesh Elastic fibersElastic fibers

Type of Loose tissue: AreolarType of Loose tissue: Areolar

Very abundantVery abundant Mesh of fibers filled Mesh of fibers filled

with holes (fluid)with holes (fluid) Limited strength Limited strength

(weak)(weak)

Type of Loose tissue: Type of Loose tissue: ReticularReticular Reticular fibers and Reticular fibers and

cellscells Near Lymph, bone Near Lymph, bone

marrow, liver, & marrow, liver, & spleenspleen

Also found around Also found around nerves, muscles and nerves, muscles and blood vesselsblood vessels

Type of Loose Tissue: Type of Loose Tissue: AdiposeAdipose Any loose CT can Any loose CT can

accumulate fataccumulate fat Very vascularVery vascular Heat dissipationHeat dissipation CushionCushion

Components of Connective TissueComponents of Connective Tissue

Extracellular matrixExtracellular matrix Fibers: collagen & Fibers: collagen &

elasticelastic glycoproteinsglycoproteins fluidfluid

Types of Tissue: ConnectiveTypes of Tissue: Connective

CellsCells resident: produce and resident: produce and

maintain extracellular maintain extracellular matrixmatrix

Fibroblasts: form fibersFibroblasts: form fibers

migratory: reaction to migratory: reaction to injury (immune injury (immune response)response)

macrophagesmacrophages mast cellsmast cells LymphocytesLymphocytes

Extracellular matrix: CollagenExtracellular matrix: Collagen

Collagen: 30% of Collagen: 30% of proteins in humanproteins in human

Tissue specific & wide Tissue specific & wide organizational organizational arrangementarrangement

Produced by many cellsProduced by many cells Fibroblasts, Fibroblasts,

chondrocytes, osteocyteschondrocytes, osteocytes

Fibers: chains of amino Fibers: chains of amino acids with peptide linksacids with peptide links

Tropocollagen: Tropocollagen: microfibrils and fibrilsmicrofibrils and fibrils

Bundle of fibrils form Bundle of fibrils form collagen fiberscollagen fibers

Extracellular matrix: CollagenExtracellular matrix: Collagen

Cross-linking: Cross-linking: stiffness and stiffness and inextensibilityinextensibility

ClassificationClassification Type I: skin, tendon, Type I: skin, tendon,

ligament etc.ligament etc. Type II: cartilageType II: cartilage Type III: loose Type III: loose

connective tissue, connective tissue, skin, blood vesselsskin, blood vessels

Extracellular matrix: ElasticExtracellular matrix: Elastic

Slender & extensibleSlender & extensible Capable of Capable of

stretching over stretching over 150% of original 150% of original lengthlength

Similar chemical Similar chemical composition composition collagencollagen

Complex glycoproteinsComplex glycoproteins

ProteoglycanProteoglycan GlycosaminoglycansGlycosaminoglycans Fill spaces between Fill spaces between

fibers (ground fibers (ground substance)substance)

negative ionsnegative ions hydrophilichydrophilic

Cells-associated Cells-associated glycoprotein: cell glycoprotein: cell adhesionadhesion

Fibronectin: cell Fibronectin: cell migrationmigration

ChondronectinChondronectin Anchorin CIIAnchorin CII

Tissue FluidTissue Fluid

Filtrate of bloodFiltrate of blood Transport of materials: food, OTransport of materials: food, O22, waste , waste

removalremoval Blockage in lymphs: edemaBlockage in lymphs: edema Gives matrix gel characteristicsGives matrix gel characteristics

BoneBone

FunctionsFunctions protectprotect storagestorage leverslevers blood productionblood production

Dynamic: remodels and Dynamic: remodels and adapts to mechanical, adapts to mechanical, hormonal and calcium hormonal and calcium changeschanges

Cortical and trabercular Cortical and trabercular types of bonetypes of bone

Bone DevelopmentBone Development

Intramembranous Intramembranous ossification (fast)ossification (fast)

Endochondral Endochondral ossification: (limb & ossification: (limb & axial bones)axial bones) cartilage calcificationcartilage calcification primary & secondary primary & secondary

center of ossificationcenter of ossification Growth plateGrowth plate Zone of ranvier Zone of ranvier

(circumferential growth)(circumferential growth)

Bone DevelopmentBone Development

Longitudinal growthLongitudinal growth chondrocytes activitychondrocytes activity Three regionsThree regions

growth: active cell growth: active cell divisiondivision

maturation: maturation: synthesize & secrete synthesize & secrete EXMEXM

transformation: transformation: calcificationcalcification

Bone DevelopmentBone Development

Intramembranous & endochondral Intramembranous & endochondral ossification can occur in the same boneossification can occur in the same bone

Primary ossification center present at Primary ossification center present at birthbirth

Affected by loading and hormonesAffected by loading and hormones Trauma or fracture can affect bone Trauma or fracture can affect bone

growth (growth plate closure or growth (growth plate closure or deformities)deformities)

Bone componentsBone components

Osteoblast & OsteocytesOsteoblast & Osteocytes Bone formationBone formation Osteoblast (bony Osteoblast (bony

surface)surface) Osteocyte: Osteocyte:

surrounded by matrixsurrounded by matrix Haversian, Volksman Haversian, Volksman

and caniliculiand caniliculi Osteoclasts: bone-Osteoclasts: bone-

reabsorbing cellsreabsorbing cells

Bone componentsBone components

Extracellular matrix: Organic, inorganic and Extracellular matrix: Organic, inorganic and fluid componentsfluid components Inorganic: Minerals (calcium) 50% volumeInorganic: Minerals (calcium) 50% volume Organic: Type I collagen & proteoglycans (39% of Organic: Type I collagen & proteoglycans (39% of

the volume)the volume) Fluid (11%)Fluid (11%) Mineral = stiffness organic = strengthMineral = stiffness organic = strength Collagen fibers most abundant in the matrixCollagen fibers most abundant in the matrix Marrow (canal system)Marrow (canal system)

Bone macrostructureBone macrostructure

Woven BoneWoven Bone disorganized pattern of collagen & osteocytes leading to disorganized pattern of collagen & osteocytes leading to

lower mechanical properties. Deposited in novo for rapid lower mechanical properties. Deposited in novo for rapid mechanical support (fracture callus)mechanical support (fracture callus)

PrimaryPrimary Must replace cartilage or woven bone. Multiple thin layers of Must replace cartilage or woven bone. Multiple thin layers of

matrix and cells, organized. Sparse vascular channelsmatrix and cells, organized. Sparse vascular channels

SecondarySecondary Deposited during remodeling, replaces primary boneDeposited during remodeling, replaces primary bone

CartilageCartilage

Three kinds:Three kinds: HyalineHyaline elasticelastic fibrocartilagefibrocartilage

Lack intrinsic blood Lack intrinsic blood vessels, nerves and vessels, nerves and lymphslymphs

Nutrients & waste: Nutrients & waste: DiffusionDiffusion

Cartilage GrowthCartilage Growth

Interstitial growthInterstitial growth chondrocyte division chondrocyte division

in young cartilagein young cartilage more flexiblemore flexible

Appositional growthAppositional growth new cartilage cells new cartilage cells

beneath beneath perichondriumperichondrium

Hyaline CartilageHyaline Cartilage

Glassy appearanceGlassy appearance Covers most joints and parts Covers most joints and parts

of respiratory systemof respiratory system Strength & StiffnessStrength & Stiffness

Type II collagen (90%)Type II collagen (90%) Proteoglycans (Negative Proteoglycans (Negative

Ions and hydrophilic (draw Ions and hydrophilic (draw water in the matrix)water in the matrix)

tends to swell but resisted tends to swell but resisted by collagen fibrilsby collagen fibrils

Age Age PG’s which PG’s which resilienceresilience

Elastic CartilageElastic Cartilage

Ear, larynx, epiglottisEar, larynx, epiglottis elastic fiberselastic fibers flexibilityflexibility

FibrocartilageFibrocartilage

Stress points due to frictionStress points due to friction Strong & flexible (filler Strong & flexible (filler

material)material) collagen fiberscollagen fibers Growth like CTGrowth like CT Four classesFour classes

Interarticular (meniscus)Interarticular (meniscus) Connecting (disks)Connecting (disks) Stratiform (protection)Stratiform (protection) Circumferential (spacer; Circumferential (spacer;

glenoid labrum)glenoid labrum)

TendonsTendons

Dense fibrous CT Dense fibrous CT parallel fibersparallel fibers

Major component Type Major component Type I collagen, few elastic I collagen, few elastic fibersfibers

Tendon sheath (pulley)Tendon sheath (pulley) Peritenon Peritenon Insertion: Sharpey’s Insertion: Sharpey’s

fibers (anchoring)fibers (anchoring)

TendonsTendons

Myotendinous JunctionMyotendinous Junction Increase surface Increase surface

areaarea reduces stressreduces stress stronger when stronger when

loaded in parallel to loaded in parallel to membranemembrane

Aponeuroses & FasciaAponeuroses & Fascia

Fibrous ribbon like tendons: Fibrous ribbon like tendons: Palmar aponeurosisPalmar aponeurosis

Fascia: all dense fibrous Fascia: all dense fibrous connective tissue that are connective tissue that are not tendon, ligaments or not tendon, ligaments or aponeurosisaponeurosis

Interwoven mesh of fibers: Interwoven mesh of fibers: stretching in all directions stretching in all directions and some cases planesand some cases planes

LigamentsLigaments

Dense connective tissueDense connective tissue hold bone to bone, resisting hold bone to bone, resisting

tensile forcestensile forces geometry of fibers specific to geometry of fibers specific to

functionfunction % of elastic fibers than in % of elastic fibers than in

tendontendon InsertionsInsertions

direct: similar to tendonsdirect: similar to tendons indirect: collagen fibers indirect: collagen fibers

blend with periosteumblend with periosteum 2/3 of a ligament is water2/3 of a ligament is water

LigamentsLigaments

Sensory receptors: Sensory receptors: information about movement, information about movement, position and painposition and pain RuffiniRuffini Pacinian corpusclesPacinian corpuscles Golgi tendon organGolgi tendon organ Free nerve endingsFree nerve endings

Joint proprioception?Joint proprioception? Information about changes Information about changes

in muscle stiffnessin muscle stiffness Yellow ligaments: mostly Yellow ligaments: mostly

elastic fibers (vocal cords, elastic fibers (vocal cords, ligamentum flava)ligamentum flava)

Ligaments and InjuryLigaments and Injury

Ankle Sprains & proprioceptionAnkle Sprains & proprioception ACL & gait & proprioceptionACL & gait & proprioception

Skeletal MuscleSkeletal Muscle

Two basic elements: Contractile Two basic elements: Contractile proteins and connective tissueproteins and connective tissue

Connective TissueConnective Tissue

Functional stiffnessFunctional stiffness Improve transmission of Improve transmission of

tensiontension reduce wear & tearreduce wear & tear

MicrostructureMicrostructure

FibersFibers MyofibrilsMyofibrils SarcomereSarcomere MyofilamentsMyofilaments

ActinActin MyosinMyosin

MicrostructureMicrostructure

MyofilamentsMyofilaments Sliding Filament Sliding Filament

theorytheory

Fibers TypesFibers TypesType I (SO) Type IIA (FOG) Type IIB (FG)

Speed Slow Fast Fast

Force Low High High

Fatigability Fatigue-resistant Fatigable Most fatigale

Capacity High AerobicLow anaerobic

Medium AerobicMedium Anaerobic

Low AerobicHigh Anaerobic

Motor Unit size Small Larger Largest

Capillary High High Low

Muscle fibersMuscle fibers

Series & parallel Series & parallel arrangementarrangement

Angle of pennationAngle of pennation longitudinal or longitudinal or

fusiform (parallel)fusiform (parallel) pennate (cross-pennate (cross-

sectional area)sectional area)

Neural ComponentsNeural Components

Motor unit: One motor Motor unit: One motor neuron and all the fibers neuron and all the fibers it controlsit controls

All-or-none-principleAll-or-none-principle muscle tensionmuscle tension

recruitment *recruitment * frequency of stimulusfrequency of stimulus

Mechanical ComponentsMechanical Components

Muscle lengthMuscle length Velocity of contractionVelocity of contraction Type of action Type of action

isometricisometric concentricconcentric eccentriceccentric

Passive propertiesPassive properties elastic energy storedelastic energy stored

Muscle stiffness: internal Muscle stiffness: internal resistance by cross-resistance by cross-bridgesbridges

Fo

rce

0

EccentricConcentric

Isometric

Tension

Length

Passive

active

Total

JointsJoints

Junction between bone-bone, Junction between bone-bone, cartilage-bone, teeth-bonecartilage-bone, teeth-bone

ClassificationClassification

SynarthrodialSynarthrodial Immovable & no joint Immovable & no joint

cavitycavity AmphiarthrodialAmphiarthrodial

slightly movable & no slightly movable & no joint cavityjoint cavity

Diarthrodial Diarthrodial (synovial)(synovial) movable with joint movable with joint

cavitycavity

Synovial jointsSynovial joints gliding (carpals)gliding (carpals) hinge (elbow)hinge (elbow) Pivot (radio-ulnar)Pivot (radio-ulnar) Ellipsoid (wrist)Ellipsoid (wrist) Condyloid Condyloid

(metacarparls)(metacarparls) SaddleSaddle Ball & socketBall & socket

Components of Synovial Components of Synovial JointsJoints Joint cavityJoint cavity Synovial membraneSynovial membrane BursaeBursae Intrinsic & extrinsic Intrinsic & extrinsic

ligamentsligaments Articular cartilageArticular cartilage FibrocartilageFibrocartilage