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PN FAZLIN ZAINI2011

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Developmental origin of musclesy The skeletal, cardia c and smoo th musc les are derived

f rom m esoder m.

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U nique terminology for the muscle cellsy S arcolemm a: cell memb rane .y S arcoplasm: cy toplasm.y S arcoplasmic reti culum : smoo th end op lasmic

reti culum.y Musc le f ibers: musc le cells.

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C lassification of muscle tissue

Musc le tissue

Skeletal musc le Cardia c musc leS moo th musc le

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SKE LE T AL MUS CLE

SMOO TH MU

SCL

E

C ARDIA C MUS CLE

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SKELETAL MU SCLELOCATIONy Usuall y atta ched to skelet on .

INNERVATIONy IS UNDE R VOLUNT ARY

CONTROL (S OMA TIC NE RVOUS S Y S TE M).

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ORG ANIZATIO N OF SKELETAL MU SCLEy Conne ctive tissue inve stment consists of :

y E pimysiumy

Perimysiumy E nd omys ium

y Functions of conne ctive tissue inve stment:y To separate musc le int o comp art ment s.y To tran sm it the force of musc le contra ction to musc le

atta chment s.y To conve y blood vessels, l ymphati cs and nerve s to the

musc le cells.

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ORG ANIZATIO N OF SKELETALM U SCLE

y Epimysiumy A den se irreg ular collagen ous co nne ctive tissue that

surround s the ENTIRE MUSCLE.y It blend s with the musc le atta chment s.

y Perimysiumy A loose collagen ous co nne ctive tissue derived f rom

epimysium , surround s the individ ual B UNDLE or FASCICLEof muscle fibers.

y Endomysiumy Compos ed of reti cular f ibers and an external lamina .

S urround s the individ ual MUSCLE CELL or MUSCLEFIB ER .

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ORG ANIZATIO N OF SKELETAL

M U SCLEy Epimysium

y S urround s the ENTIRE MUSCLE.y Perimysium

y S urround s the individual B UNDLE or FASCICLE of musc le f ibers.y Endomysium

y S urround s the individ ual MUSCLE CELLor MUSCLE FIB ER .

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PE RIMY S IUME

PI

M Y S

IUM

E NDOMY S IUM

F

F = Fascicle

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MIC RO SC OP IC OR HISTO LOG ICALCHAR AC TER ISTIC FEATU R ES OF SKELETAL MU SCLEF IBER S

y Long and unbran ched cy lindri cal cells, length is bet ween 1-30mm.

y Multin ucleated with peripherall y located f latten nuclei just beneath the sarcolemm a.

y Presence of cross-striati ons of alternating dar k and light band s.

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SKELETAL MU SCLES

Longit udinal section

Cross section

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C O MPO NENTS OF A SKELETAL MU SCLEF IBER

y MYOFIB RILS are main compo nent of the sarcoplasm.y Long cy lindri cal f ilament ous bu ndle s oriented parallel to

each other and to the long axis of the musc le f iber.y Made up of co ntra ctile protein s or myof ilament s.y Has prom inent cross-s triati ons which is due to

arrange ment of the contra ctile protein s or myof ilament sknown as actin (thin myof ilament s) and myos in (thi ckmyof ilament ).

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y E ach myof ibril consists of myof ilament s

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C ross-striations of the myofibrilsy I band/ Isotrop ic band

y LIght band, contain s thin myof ilament s ( A CTIN).y A band/ A nisotrop ic band

y D A rk band, contain s both thi ck myof ilament s (MYOS IN)and thin myof ilament s ( A CTIN).

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C ross-striations of the myofibrilsy

Z liney Bisects the I band, serve s as the atta chment site for thin

myof ilament s (actin ).y H band

y A pale area in the center of A band, represent s the area where thin myof ilament s are not present .

y M liney Bisects the H band, where thi ck myof ilament s (myos in) are

inter conne cted .

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Sacromerey Contra ctile unit of skeletal musc le f ibers.y It extend s f rom o ne Z line to the next Z line .y Abou t 2.5 m long in resting musc le.y R esting sacromere consists of partiall y o verlapp ing thin

myof ilament s (actin ) and thi ck myof ilament s (myos in ).y S hortening of the sacromere during contra ction is NOT due

to a shortening of the myof ilament s, bu t it is due to an increa se in the amou nt of o verlap bet ween the myof ilament s.

Z line

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Alterations in sacromere during contractiony S acromere s (S ) shorten as

the thin myof ilament s(actin ) slide past the thi ck myof ilament s(myos in).

y Z line interval narr ows.y W idth of the I and H

band s decrea ses.

y W idth of A band (dar kband ) remain sunchanged .

Z line

Z line Z line

Z line

A

A

H

H

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T tubules and sarcoplasmic reticulumT wo tubu lar systems :y T tubules (transverse

tubules)y tubular invaginations of

the sarcolemma that extend tran s versel y int othe musc le cell tosurround each myof ibril at the junction of the A and Iband s.

y Terminal cisternaey Expanded ends of the

sarcoplasmic reticulumat the junction of the A and

I band s.

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T tubules and sarcoplasmic reticulumy TRIAD OF THE SKELETAL MUSCLE

y One T tubule between two terminal cisternae

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T tubules and sarcoplasmic reticulumy Function of T tubu le- f acilitate s the cond uction of

waves of depolarizati on along sarcolemm a.

y Function of sarcoplasmic reti culum- regulate s musc le contra ction thr ough contr olled sequestering (leading to relaxati on) and relea se (leading to contra ction) of

calcium ion (Ca2+

) within sarcoplasm.

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Contraction of skeletal muscley Calcium ions are relea sed int o sarcoplasm,

bind to TnC subunit of troponin ; causes the shifting of the tropomyosin int o dee per position; exposing the myosin-binding siteon the actin .

y The myosin head binds to actin and ATP

breaks down int o ADP, producing energ y that causes the movement of myosin head .y Mo vement of the myos in head pulls the actin

past the myosin .y Intera ction of actin and myos in by sliding

f ilament produce contraction .y Contra ction results in shortening of the

length of muscle fibers and the wholemuscle tissue.

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Contraction of skeletal muscle

Ca2+ bind to TnC subu nit of troponin

Causes sh if tin of tropo yos in int odee per pos ition

E xposes the yosin-bindin

site on the actin

Myosin head bind s to the actin

E ner y isrelea sed f ro the

TP break do n

E ner y causes the o vement of the m yosin head

Mo vement of the m yosin head

pu lls the actin past the m yosin .

Intera ction of actin and m yosin by slidin

f ilament produce contra ction

Sho rtenin of the len t h of muscle

f ibers and the ho le muscle tissue.

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R EG ENER ATIO N OF SKELETAL MU SCLEy Skeletal musc les do not have the capability of

mitotic activity.y

Presence of stem cells known as satellite cells which ma y underg o mitosis subs equent to musc le in jur y.

y Skeletal musc le can underg o hypertrophy (increase

the size of the cells) by increasing the number of myofibrils.

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2 . CAR DIAC MU SCLEmyocardiumLOCATIONy In the heart .

INNERVATIONy IS UNDE R INVOLUNT ARY CONTROL

(AUTONOMI C NE RVOUS S Y STE M).

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ARR ANG EMENT OF CAR DIAC MU SCLEy Bran ching cardia c musc le

cells are arranged in

la y ers known as laminae .y Laminae are separated form one another by slender conne ctive tissue

sheet s that conve y blood vessels, nerve s, and cond ucting system of the heart .

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MIC RO SC OP IC OR HISTO LOG ICALCHAR AC TER ISTIC FEATU R ES OF CAR DIAC M U SCLEF IBER S

y S horter than skeletal musc les, cy lindri cal B RANCHING CELLS, length is bet ween 85-100m.

y SINGLE, oval , centrally placed nucleus , t wonuclei occasional y present .

y CROSS STRIATIONS .y INTERCALATED DISKS -

higl y specialized end toend junctions or inter cellular junctions, uniq ue and mos t disting uish chara cteri stic.

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CA

RDIA

CM

US

CLE

Longit udinal

section

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CAR DIAC M U SCLE

Longit udinal section

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C O MPO NENTS OF A CAR DIAC MU SCLEy S tr ucture and function of the contra ctile protein s in

cardia c musc le are almos t same as in skeletal musc le,

however there are some diff eren ces.y DYADS : ONE T-TU B ULE AND ONE SACROPLASMIC

RETICULUM TERMINAL CISTERN located near toZ

line .

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Intercalated disks3 t ypes of junctionsy Fascia adheren s

similar to Z line, site for thin myof ilament s(actin ) atta chment s.

y Desmosom e bind s

cardia c cells together .y Gap junction permits

rapid f low of signal f romone cell to the next cell.

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C AR DIAC M U SCLE intercalated disks (D)

Longit udinal section

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R egeneration of cardiac muscle?y Cardia c musc le

y The se cells DO NOT have the capabilit y of MITOTIC

A CTIVIT Y there fore INCAPA B

LE OF REGENERATION .y Following damage, f ibrob lasts invade the damaged area, form f ibrous co nne ctive tissue (scar tissue).

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3 .SM

OOTH M

US

CLEvisceral muscleLOCATIONS

y W alls of hollow viscera eg: gastrointe stinal tra ct, some of reproductive tra ct, urinar y tra ct.

y

W alls of blood vessels.y Larger duct of compou nd gland s.y R espirat or y passages.y S mall bundle s within der mis of skin .

INNERVATIONy IS UNDE R INVOLUNT ARY CONTROL (AUTONOMI C

NE RVOUS S Y S TE M).

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R espirat or y passages Blood vessel

Gastrointe stinal tra ct

ARROW S showing the smoo th

musc les

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ARR ANG EMENT OF SMOO TH MU SCLEy Their cells are arranged in the form of contin uous

net work, their tapered end s f it int o existing spacesbet ween the expanded part s of ad jacent smoo th

musc le cells (interdigitation ).

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ARR ANG EMENT OF SMOO TH MU SCLEy S moo th musc le cells usu all y

form sheets of variousthickness .

y Usuall y in two layersperpendi cular to each other .

y inner circulary outer longitudinal

y to permit wave of peristal sise.g dige stive and urinar y systems.

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CO NNEC TIVE TISSU E CO VER ING OF SMOO TH MU SCLEF IBER

y E ach smoo th musc le is surrounded by external lamina .y E mbedded in external lamina are numerous reti cular

f ibers.y The y serve to comb ine the force generated by each

smoo th musc le f iber int o a concerted action eg, peristal sis in the inte stine .

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MIC RO SC OP IC OR HISTO LOG ICALCHAR AC TER ISTIC FEATU R ES OF SMOO TH MU SCLEF IBER S

y S horter than skeletal musc le, length is bet ween 20 -500 m.

y Unbran ched fusiform or spindle-shaped cells with tapering end s.

y Single , centrally placed ovalnucleus at the wide st part of the cell, the nucleus can appear spiraled sha ped when the f iber iscontra cted .

y No striations .

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SMOO TH MU SCLES

Longit udinal section Cross section

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C O M PO NENTS OF A SMOO TH MU SC LEF IBER y Contra ctile protein s of

smoo th musc le are notarranged longitudinally inmyofibrils as in skeletal and cardia c musc les.

y Clumps of contractileproteins or myofilamentsarranged in criss-crossedpattern no striation.

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y Den se bodie s an chor contra ctile protein s to the sarcolemm a and hold the m within sarcoplasm.

y No T tubules , presen ce of caveolae(invaginati ons of

sarcolemm a) act as T-tubu les, function in relea se and sequestering of calcium ions.

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TWO TYP ES OF SMOO TH MU SCLEy MULTIUNIT SMOOTH MUS CLEy UNIT ARY S MOOTH MUS CLE (S INGLE -UNIT,

VA S

CULAR)

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Multiunit smooth muscley Pha sic smoo th musc le y Each muscle cell ha s its own nerve supply , there fore

the y can contract independently of one an other .

y Iris of the e y e and vas de f eren s.

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U nitary or single-unit smooth musclesy Tonic smoo th musc ley Cell memb rane form GAP JUNCTIONS with th ose of

ad jacent smoo th musc le cells.y Nerve fibers supp l y a few of the muscle fibers .y There fore the y cann ot contra ct inde pendentl y of one

another .y Most of smooth muscle in wall of hollow viscera

eg inte stine, ureter, f allopian tube cells are arranged in sheet s with circular or longit udinal arrange ment .

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Contraction of smooth muscley Calcium ions are relea sed int o

sarcop lasm and bind to calmodulin (calcium b inding protein ) and formcalcium-c almodulin comp lex.

y This comp lex activate s myos in light -chain kina se enz yme, which phosphor y late s myos in, permits it to bind to actin .

y Intera ction of actin and myos in by sliding f ilament produce contra ction .

y Contra ction results in shortening of the cell f rom elongated to a globu lar sha ped .

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Contraction of smooth muscle

Ca2+ Calmodulin

Activati on of myos in light -chain kina se

Musc le contra ction

Calcium-c almodulin comp lex

Phosphor y lati on of myos in

Intera ction of actin and myos in

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R EG ENER ATIO N OF SMOO TH MU SCLEy Smoo th musc le

y The se cells have the capability of mitotic activity .

y The y also can underg o h yperplasia and h ypertr oph y (eg;

pregnant uter us).

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E ND?

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QUIZ

y Identi fy thi sstr ucture as a

whole.y S

tate the histological chara cteri sticf eat ures of thi sstr ucture .

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QUIZ

y Identi fy thi sstructure as a

whole.y S tate the

histological chara cteri sticf eat ures of thi sstructure .

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QUIZ

y Identi fy thi s str ucture as a whole.y S tate the histological chara cteri stic f eat ures of thi s

str ucture .

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COMPARISON OF THREE TYPES OF MUSCLE

Feature Skeletal Cardiac Smooth

Cell shape

Nuclei:

Number

ShapeLocation

Striations

Regeneration

Type of control

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COMPARISON OF THREE TYPES OF MUSCLEFeature Skeletal Cardiac Smooth

Cell shape Elongated andcylinder shaped Cylinder andbranchingpattern

Fusiform or Spindle shapedwith taperingends

Nuclei:

Multinucleated One (or two) OneNumber Shape Flat Oval Oval

Location Periphery Center Center

Striations Present Present Absent

Regeneration Yes, via satellitecells

No Yes

Type of

control

Voluntary Involuntary Involuntary

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