muscle connective tissues 4

8/6/2019 Muscle Connective Tissues 4

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Animal Tissues

Muscle tissue

Connective tissue


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Muscle TissueMuscle Tissue

The major function of muscle is to producemotion

Muscle tissue consists of long, excitable

cells capable of contraction Muscle is the most abundant tissue in most

animals There are three types of vertebrate

muscles:i. Smooth muscleii. Cardiac muscleiii. Skeletal muscle voluntary muscle

Involuntary muscle


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Skeletal MuscleSkeletal Muscle

AA skeletalskeletal musclemuscle isis mademade upup ofof numerous,numerous,veryvery longlong musclemuscle cells,cells, calledcalled musclemuscle fibers,fibers,whichwhich lielie parallelparallel toto eacheach otherother withinwithin thethemusclemuscle

Each muscle fiber is multinucleated with thenuclei at the periphery.

Each multinucleated muscle fiber is located

just beneath the cell surface membrane

called the sarcolemma. The cytoplasm in the muscle fiber is called

sarcoplasm and contain many mitochondria.


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EachEach musclemuscle fiberfiber contractscontracts byby meansmeansofof substructuressubstructures calledcalled myofibrilsmyofibrils thatthat

containcontain highlyhighly orderedordered arraysarrays ofof actinactinandand myosinmyosin myofilaments,myofilaments, thatthat whenwhenalligned,alligned, givegive thethe musclemuscle fiberfiber itsitsstriatedstriated looklook


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Cardiac MuscleCardiac Muscle

CardiacCardiac musclemuscle isis thethe mainmain tissuetissue ofof thethe heartheart

Cardiac muscle cells have a singlenucleus, many mitochondria and are striated.

The muscle cells are connected to oneanother by intercalated discs (gap junction)

The fibers are elongated, cylindrical that

branch and rejoin, forming complex networks The cardiac muscles bring about the

continuous, rhythmic contractions of theheart and pump blood around the body


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Nucleus

Intercalateddiscs

25 m

Z-line

Mitochondria

1 m


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Cardiac muscleCardiac muscle

abutting ends of twocardiac muscle cells(intercalated disc)

comm

unication junction


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MyogenicMyogenic :: originatingoriginating inin oror producedproduced bybymusclemuscle cellcell

TheThe contractionscontractions ofof cardiaccardiac musclemusclefibersfibers areare describeddescribed asas myogenic,myogenic, sincesincetheythey producedproduced spontaneously,spontaneously, withoutwithoutrequiringrequiring stimulationstimulation fromfrom nervenerve cellscells


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Smooth MuscleSmooth Muscle

SmoothSmooth musclemuscle (visceral(visceral muscle)muscle) isis foundfound ininthethe inin thethe wallswalls ofof thethe digestivedigestive tract,tract,uterus,uterus, bloodblood vesselsvessels andand manymany otherother internalinternal

organsorgans SmoothSmooth musclemuscle isis organizedorganized intointo sheetssheets ofof

elongated,elongated, spindlespindle--shaped,shaped, pointedpointed--endend cellscells,,eacheach containingcontaining aa single,single, centralcentral nucleusnucleus

The muscle fibres do not contain visiblecross striations.


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cellsteasedapart forclarity

SMOOTH MUSCLE


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Exercise to wake the mindExercise to wake the mind

ComparisonComparison ofof thethe threethree typestypes ofofmusclesmuscles

PastPast yearyear questionsquestions ((20052005//20062006))

CompareCompare andand contrastcontrast thethe cardiaccardiac

musclemuscle tissuetissue andand skeletalskeletal musclemuscle tissuetissue..

(8 marks)(8 marks)


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Connective TissuesConnective Tissues

Connective tissue functions mainly tobind and support other tissues. Connective tissues have a sparse population

of cells scattered through an extracellularmatrix.

The matrix generally consists of a web offibers embedding in a uniform foundation

that may be liquid, jellylike, or solid. In most cases, the connective tissue cells

secrete the matrix.


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The major types of connective tissues

in vertebrates are :i. loose connective tissue

ii. adipose tissue

iii. fibrous connective tissueiv. cartilage

v. bone

vi. blood.

Each has a structure correlated with itsspecialized function.

SPECIALCONNECTIVETISSUES

Will be discussed in detail


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CartilageCartilage Cartilage has an abundance of

collagenous fibers embedded in arubbery matrix made of a substance

called chondroitin sulfate, a protein-carbohydrate complex. Chondrocytes, the cells of the

cartilage,live within spaces called lacunae,

secrete collagen and chondroitin sulfate. These cells remain alive even there is no

blood within the cartilage matrix They receive O2 and nutrients by diffusion

from surrounding blood vessels


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The composite of collagenous fibers andchondroitin sulfate makes cartilage a strongyet somewhat flexible support material.

The skeleton of a shark is made of cartilageand the embryonic skeletons of manyvertebrates are cartilaginous.

We retain cartilage as flexible supports in

certain locations, such as the nose, ears, andvertebral disks.


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Anatomy of a Long BoneAnatomy of a Long Bone

LongitudinalLongitudinal sectionsection ofof aa longlong boneboneshowsshows aa hollowhollow cavity,cavity, medullarymedullary cavity,cavity,boundedbounded atat thethe sidessides byby compactcompact boneboneandand atat thethe endend byby spongyspongy bonebone.. CompactCompact bonebone containscontains manymany osteonsosteons wherewhere

osteocytesosteocytes lielie inin lacunaelacunae..

SpongySpongy bonebone hashas numerousnumerous barsbars andand platesplatesseparatedseparated byby irregularirregular spacesspaces.. SpacesSpaces filledfilled withwith redred bonebone marrowmarrow..


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Fig. 50.4


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TheThe microscopicmicroscopic structurestructure ofof hardhardmammalianmammalian bonebone consistsconsists ofof repeatingrepeating

unitsunits calledcalled osteonsosteons (Harvesian(Harvesian systems)systems) Each osteon has concentric layers of

mineralized matrix deposited around a centralcanal containing blood vessels and nerves that

service the bone.


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OnceOnce osteoblastosteoblastbecomebecome trappedtrapped inin theirtheir

ownown secretions,secretions, theytheyareare calledcalled osteocytesosteocytes(bone(bone cells)cells)

Osteocytes are locatedin spaces called lacunae

surrounded by a hardmatrix and areconnected to eachother by cell extensionscalled canaliculi

In long bones, only theouter area is hard andcompact; the inner areais filled with spongybone tissue calledmarrow

Cytoplasmicextensions

Lacuna

Matrix

Osteocyte


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Spongy

boneCompact

bone Haversiancanal

Osteon



Lacuna

Matrix

Osteocyte


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Volkmann Canal

Volkmann canals connect theHarvesian canals ofadjacent osteons to each

other


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BloodBlood

BloodBlood isis classifiedclassified asas aa connectiveconnective tissuetissuebecausebecause itit containscontains abundantabundantextracellularextracellular material,material, thethe fluidfluid plasmaplasma The plasma, consists of water, salts, and a

variety of dissolved proteins. Plasma from which the fibrinogen and other

clotting factors have been removed is

called the serum Suspended in the plasma are erythrocytes

(red blood cells), leukocytes (white bloodcells) and cell fragments called platelets.


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ErythrocytesErythrocytes

(Red blood cells, RBC

s)(Red blood cells, RBC

s) Erythrocytes,Erythrocytes, alsoalso calledcalled thethe RBCs,RBCs, areare highlyhighlyspecializedspecialized forfor transportingtransporting oxygenoxygen

EachEach mammalianmammalian RBCRBC isis aa flexible,flexible, biconcavebiconcavedisc,disc, 77 toto 88 mm inin diameterdiameter andand 11 22 mm thickthick

ItsIts biconcavebiconcave shapeshape providesprovides aa highhigh ratioratio ofofsurfacesurface areaarea toto volume,volume, allowingallowing efficientefficientdiffusiondiffusion ofof OO22 andand COCO22 intointo andand outout ofof thethecellcell

InIn anan adultadult human,human, aboutabout 3030 trilliontrillion RBCsRBCscirculatecirculate inin thethe blood,blood, approximatelyapproximately 55 millionmillionperper ll..


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DuringDuring thethe RBCsRBCs maturationmaturation inin mammals,mammals,theythey loselose theirtheir nucleus,nucleus, mitochondriamitochondriaandand endoplasmicendoplasmic reticulumreticulum

Thus,Thus, aa mammalianmammalian RBCsRBCs areare relativelyrelativelyinactiveinactive metabolicallymetabolically

ErythrocytesErythrocytes areare producedproduced withinwithin thethe

redred bonebone marrowmarrow ofof certaincertain bonesbones ::vertebrae,vertebrae, ribs,ribs, breastbone,breastbone, skullskull bonesbonesandand longlong bonesbones


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AsAs anan RBCRBC develops,develops, itit producesproduces greatgreatquantitiesquantities ofof hemoglobin,hemoglobin, thethe oxygenoxygen--transportingtransporting pigmentpigment thatthat givesgives vertebratevertebratebloodblood itsits redred colourcolour

EachEach RBCRBC containscontains aboutabout 300300 millionmillion moleculesmoleculesofof hemoglobinhemoglobin

TheThe lifelife spanspan ofof aa humanhuman RBCRBC isis aboutabout 120120daysdays

InIn aa humanhuman body,body, moremore thanthan 22..44 millionmillion arearedestroyeddestroyed everyevery second,second, soso anan equalequal numbernumbermustmust bebe producedproduced inin thethe bonebone marrowmarrow totoreplacereplace themthem..


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LeukocytesLeukocytes

TheThe leukocytesleukocytes oror WBCsWBCs areare specializedspecialized totodefenddefend thethe bodybody againstagainst harmfulharmful bacteriabacteria andandotherother microorganismsmicroorganisms

LessLess thanthan 11%% ofof thethe humanhuman bloodblood areare

WBCs

WBCs

WBCsWBCs havehave nucleinuclei andand mitochondriamitochondria butbut lacklackthethe pigmentpigment hemoglobinhemoglobin

LeukocytesLeukocytes areare notnot confinedconfined toto thethe bloodblood asas

erythrocyteserythrocytes are,are, butbut cancan migratemigrate outout ofofcapillariescapillaries intointo thethe interstitialinterstitial (tissue)(tissue) fluidfluid


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Types of LeukocytesTypes of Leukocytes

Human blood contains five types ofleukocytes, classified as either :

Granular

Agranular

Both types are manufactured in the redbone marrow


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Granular LeukocytesGranular Leukocytes

AreAre characterizedcharacterized byby large,large, lobedlobednucleinuclei andand distinctivedistinctive granulesgranules inin theirtheircytoplasmcytoplasm

ThereThere threethree typestypes ::i.i. NeutrophilsNeutrophils

ii.ii. EusinophilsEusinophils

iii.iii. BasophilsBasophils


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Agranular LeukocytesAgranular Leukocytes

They lack large distinctive granulesand their nuclei are rounded orkidney-shaped

There are two types :i. Lymphocytes

T-lymphocytes

B-lymphocytesii. Monocytes


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Organs and Organ SystemsOrgans and Organ Systems

OrgansOrgans areare bodybody structuresstructures composedcomposedofof severalseveral differentdifferent tissuestissues thatthat formform aastructuralstructural andand functionalfunctional unitunit

InIn allall butbut thethe simplestsimplest animalsanimals (sponges(spongesandand cnidarians),cnidarians), differentdifferent tissuestissues areareorganizedorganized intointo organsorgans


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Fig 49 4


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Fig. 49.4


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In some organs the tissues are arranged inlayers.

For example, the vertebrate stomach has fourmajor tissues layers. A thick epithelium lines the lumen and

secretes mucus and digestive juices into it.

Outside this layer is a zone of connectivetissue, surrounded by a thick layer ofsmooth muscle.

Another layer of connective tissueencapsulates the entire stomach.


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Organ systems carry out the major body functions ofmost animals.

Each organ system consists of several organs andhas specific functions.


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Cell RecognitionCell Recognition

HowHow dodo cellscells recognizerecognize eacheach other?other? ItIt isis veryvery importantimportant thatthat thethe humanhuman bodybody

shouldshould bebe ableable toto recognizerecognize selfself andand nonnon--

selfself.. SelfSelf :: thethe cellscells withinwithin youryour ownown bodybody andand havehave

theirtheir ownown particularparticular setssets ofof surfacesurfacemarkers/chemicalsmarkers/chemicals

NonNon--selfself :: foreignforeign cellscells.. CellsCells withwith differentdifferentchemicalschemicals onon theirtheir surfacessurfaces.. EgEg:: invadinginvadingmicroorganismsmicroorganisms


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muscle connective tissues 4

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