fisiologi otot (fs)

7/25/2019 Fisiologi Otot (FS)

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ByDr.H.Gusbakti,MD, MSC,PKK,AIFM

Professor of Physiology

University Islamic Of North Sumatera

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MUSCLE TISSUE

Muscles in human bodySpecialised excitable tissues~ 50 % body weiht!bility to cont"actCont"actions p"o#ide mo#ements$o wo"

Mo#e body o" limbs&ush' pull o" hold an exte"nal load o" ob(ectMix o" mo#e )ood th"ouh the ast"ointestinal t"ac&ump blood out o) the hea"t to the blood #essels

Cont"act ute"us )o" bi"th o) )oetusMictu"ition and de)aecation

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MUSCLE *+ T,&E

Th"ee types o)muscle-./Seletal muscle/Ca"diac muscle

1/Smooth muscle

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Seletal Muscle

Lon cylind"icalcells

Many nuclei pe"cell

St"iated

2olunta"y 3apid

cont"actions

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Ca"diac Muscle

4"anchin cells

*ne o" two nuclei pe" cell

St"iated

In#olunta"y

Medium speed cont"actions

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mooth Muscle

+usi)o"m cells

*ne nucleus pe" cell

onst"iated

In#olunta"y

Slow' wa#e6lie cont"actions

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Basic Characteristics of

Muscle TissuesExcitabilityResponse to stimuli

Conductivity

Able to conduct action potentialContractibilityAble to shorten in length

Extensibility

Stretches when pulledElasticityTends to return to original shape length a!ter

contraction or extension

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Skeletal Muscle

Attached to bones moves skeleton"akes up #$% o! &' in men and (2% o! &' in women

"ain !unctions o! skeletal muscle)*nitiate movements+er!orm work"aintain postureStabilise ,oints

-enerate heat

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Level of Organisationin SkeletalMuscle

Skeletal "uscle.organ/

0ascicle

.bundle o! muscle !ibres/

"uscle 0ibre.cell/

"yo!ibril

Sarcomere

0ilaments.Thin actin/

.Thick myosin/ gusbakti12


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Membranes of Skeletal

Muscle"uscle surrounded by epimysium&undles o! !ibres.!ascicles/ surrounded byperimysium

"uscle !ibresurrounded by endomysium

These connective tissues extend beyond the ends o!muscle to !orm tendons that attach muscle to bones

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Skeletal Muscle Fibre

3arge4 elongated4 shape like

cylinder

1$ 1$$ 5m in diameter4 up to

67$4$$$ 5m .$867 m/ in length

.extend entire length o! muscle/"ultinucleated with abundant o!

mitochondria

Sarcolemma.cell membrane/

Sarcoplasm.muscle cellcytoplasm/

Sarcoplasmic reticulum .modi!ied

ER/

Transverse tubules .Ttubules/

internal conduction system

"yo!ibrils !or contraction

Sarcomeresregular arrangemen

o! thin .actin/ thick .myosin/

!ilaments

Actin!ilaments interdigitatewith

myosin !ilaments

Appears striated undermicroscope

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Structure of a Skeletal Muscle

Fibre

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Electron Micrographof Skeletal Muscle

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Sa"come"e

The )unctional unito) seletal muscle

Multi6p"otein complexes composeddi7e"ent 8lament systems-

Thin 8lament system

Thic 8lament system

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Muscle Tissue

Seletal Muscle

Ca"diac Muscle

Smooth Muscle

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Microanatomy ofSkeletal Muscle

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9 line 9 line

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: &and

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Sarcomere Relaxed

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Sarcomere PartiallyContracted

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Sarcomere CompletelyContracted

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&inding Site Tropomyosin

Troponin

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"yosin

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Sa"come"e sarcomere

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S


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Sa"come"e

Sa"come"e

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Sarcomere

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A band .dark band/consists o! a stacked set o! thick !ilaments

* band .light band/Consists o! the array o! thin !ilaments4 and is the region where they do

not overlap the thick !ilaments

: ;oneThe lighter area in the centre o! A band where the thin !ilaments do notoverlap with thick !ilaments

" lineConsists o! supporting proteins that hold the thick !ilaments together

vertically within each stack9 lineConsists o! supporting proteins that hold the thin !ilaments together

vertically within each stack

Area between two 9 lines is called a sarcomere

Sarcomere

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Thin 0ilament

Actin

Spherical in shape4 with a special binding site !or attachment withmyosin cross bridge


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Thin 0ilament

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Thin 0ilamentTroponinComplex

TnT binds to tropomyosin

TnC binds to Ca2=

Tn* binds to actin gusbakti12


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Thick 0ilament

Each thick !ilament is composed o!

several hundred myosin molecules

packed togetherA single myosin protein looks like 2

gol! clubs with sha!ts twisted about

one another"yosin molecules have elongated

tails globular heads:eads !orm crossbridgesbetween

thick and thin !ilaments during

contraction

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Thick 0ilamentCross &ridges

Each cross bridge has two

important sites)

An actinbinding siteA myosin AT+ase site

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>rganisationo! Actinand "yosinCross bridges

Thin !ilaments arearranged hexagonally

around thick !ilamentsEach thin !ilament is

surrounded by ( thick

!ilamentsCross bridges pro,ect

!rom each thick !ilamentin all ? directions toward

the surrounding thin

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Contraction o! "uscle 0ibres

@one by sliding actin !ilaments

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Sliding 0ilament TheoryContraction occurs by actin !ilaments sliding into

myosin !ilamentsActin !ilaments move4 myosin !ilaments remain

stationarySarcomeres shortenedCause whole muscle to contract

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Role o! Calcium

Ca2=released !rom

sarcoplasmic reticulumCa2=binds to troponin C

Troponin turns4 moves

tropomyosin exposes actin

active site

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Contraction o! "uscle 0ibresRole o! Calcium

"yosin head binds to actinactive site4 !orm crossbridge4 move

producespower!ul strokesActin slides in muscle !ibre

contractsCrossbridge action continues

while Ca2=is present'hen action potential stops4

Ca2=is pumped back to SR

Tropomyosin covers back actinsactive siteRelaxation occurs

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Contraction o! "uscle 0ibresRole o! Calcium

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Contraction o! "uscle 0ibresRole o! AT+

AT+ split by myosin AT+ase B A@+ and

Pi remain attached to myosin; energy is

stored within the cross bridge"g2=must be attached to AT+ be!ore

AT+ase can split the AT+Ca2= released on excitation4 removes

inhibitory in!luence !rom actin energised myosin cross bridge bind with

actinCross bridge bends and causes power

stroke

A@+ andPiare released after powerstroke is completedAT+ase site is !ree !or attachment o!

another AT+Attachment o! new AT+ permits

detachment o! cross bridgegusbakti12

C t ti ! " l 0ib


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Contraction o! " scle 0ibres


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All the cross bridges power strokes are directed

toward the centre o! the sarcomereAll ? o! the surrounding thin !ilaments on each end

o! the sarcomere are pulled inward simultaneously

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Rigor "ortisD Sti!!ness o! death a

generalised locking in place o!

skeletal muscle that begins ( to #hours a!ter death

0ollowing death4 FCa2=Gibegins

to rise

This Ca2=moves the regulatory

proteins aside4 permitting actin

bind with the myosin cross bridges4

which were already charged with

AT+ be!ore death

Ho !resh AT+ available a!terdeath4 actin and myosin remain

bound in rigor complex

Resulting in sti!!ness condition

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Electrical +roperties o! "uscle 0ibres

Resting membrane potential)I$mJ

'hen an adeKuate stimulus is given

action potential

potential) =($mJ

@epolarisation is due to in!lux o! Ha=Time taken) 1 2 msec

Absolute re!ractory period relativere!ractory period present

Action potential results in muscle

contraction

Me

mbranpotensial(mV)

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A ti + t ti l d " l T it h


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Action +otential and "uscle Twitch

Tension

M

embranpotensial(mV)

3atent period

The delay between stimulation and theonset o! contraction .a !ew msec/

Contraction timeThe time !rom the onset o! contraction

until peak tension is developed .average L

7$ msec/

Relaxation timeThe time !rom peak tension until

relaxation .L 7$ msec or more/

A single contractionMrelaxation cycle

is called a muscle twitch

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ExcitationContraction Coupling

Re!ers to the series o! events linking muscleexcitation .electrical events/ to muscle contraction

.mechanical events/

Electrical events presence o! action potential"echanical events crossbridge activity

Electrical events come !irst be!ore mechanicaleventsCa2= is the link between excitation and contraction

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The sur!ace membrane at each

,unction o! A band and * band

dips into muscle !iber to !orm a

T tubuleAction potential on the sur!ace

membrane spreads down into the

T tubule

The presence o! local actionpotential in T tubule induces

permeability changes in the

sarcoplasmic reticulum

Sarcoplasmic Reticulum .SR/

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Release o! Ca2= !rom SR

'hen action potential is

propagated down the T tubules4

local depolarisation activates the

voltagegated dihydropyridinereceptors in T tubuleThese activated receptors in

turn trigger the opening o!

Ca2=release channels .alias

ryanodine receptors/ in ad,acent

lateral sacs o! SRCa2= is released into the

surrounding sarcoplasm

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Relaxation o! "uscle 0ibres

When ACh is removed from the neuromuscular junction, themuscle fibre action potential ceasesNo longer a local potential in T tubules to trigger Ca2+

releaseReleased Ca2+ is pumped bac into the lateral sacs b!

Ca2+"AT#ase pumpRemoval of sarcoplasmic Ca2+allo$s the troponin"

tropom!osin comple% to slip bac into its blocing positionActin and m!osin are no longer able to bind at the cross

bridgesThin filaments are able to return passivel! to their resting

positionRela%ation occurs

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E i i C i C li


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ExcitationContraction Coupling and Relaxation


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ExcitationContraction Coupling and RelaxationSummary o! Events

18Ach released !rom the terminal o! a motor neuron initiates an action potential in

the muscle !ibres

28"uscle action potential travels down T tubule

(8Causes SR to release Ca2= into sarcoplasm

#8Ca2= binds to troponin4 exposing actins crossbridge binding sites

78"yosin head binds to active site4 !orm crossbride4 moves and produces power

stroke

?8Actin slides in4 muscle !ibre contracts resulting in contraction o! whole muscle

68A@+ andPiare released after the power stroke is complete

N8Hew AT+ binds to myosin headB detachment o! the cross bridge

I8Crossbridge action continues while Ca2= is present1$8'hen action potential stops4 Ca2= pumped back to SR

118Tropomyosin covers back active sites

128Relaxation occurs

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eu"omuscula" 9unction

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!cetylcholine *pens a:


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!cetylcholine *pens a:Channel

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Muscle Contraction


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Muscle ContractionSummary

e"#e impulse "eaches myoneu"al(unction

!cetylcholine is "eleased )"om moto"

neu"on !ch binds with "ecepto"s in the muscle

memb"ane to allow sodium to ente"

Sodium in;ux will ene"ate an actionpotential in the sa"colemma

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Muscle Contraction


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Muscle ContractionContinued

!ction potential t"a#els down T tubule

Sa"coplamic "eticulum "eleasescalcium

Calcium binds with t"oponin to mo#ethe t"oponin' t"opomyosin complex

4indin sites in the actin 8lament a"e

exposed

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Muscle Contraction


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Muscle ContractionContinued

Myosin head attach to bindin sitesand c"eate a powe" st"oe

!T& detaches myosin heads and

ene"i


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Motor UnitAll the muscle cells

controlled by one nerve cell

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Motor Unit Ratios

4ac muscles

& .-.00

+ine" muscles

& .-.0

Eye muscles

& .-.

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ATP

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Creatine

Molecule capable o) sto"in !T&ene"y

Creatine = AT+ Creatine phosphate = A@+

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Creatine Phosphate

Molecule with sto"ed !T& ene"y

Creatine = AT+Creatine phosphate= A@+

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Muscle Fatiue

Lac o) oxyen causes !T& de8cit

Lactic acid builds up )"om anae"obic"espi"ation

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Muscle Atrophy

=eaenin and sh"inin o) a muscle

May be caused

& Immobili


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Muscle !ypertrophy

Enla"ement o) amuscle

Mo"e capilla"ies Mo"e

mitochond"ia

Caused by

& St"enuous exe"cise

& Ste"oid ho"mones

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Steroid !ormones

Stimulate muscle "owth andhype"t"ophy

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Muscle Tonus

Tihtness o) a muscle

Some 8be"s always cont"acted

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Tetany

Sustained cont"action o) a muscle

3esult o) a "apid succession o) ne"#eimpulses

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Tetanus

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Refractory Period

4"ie) pe"iod o) time in which musclecells will not "espond to a stimulus

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Refractory

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Skeletal "uscle Cardiac "uscle

Refractory Periods

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"sometric Contraction

&"oduces no mo#ement

Used in

& Standin

& Sittin

& &ostu"e

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"sotonic Contraction

&"oduces mo#ement

Used in

& =alin

& Mo#in any pa"t o) the body

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