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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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
!ilamentsgusbakti12
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Contraction o! "uscle 0ibres
@one by sliding actin !ilaments
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Contraction o! "uscle 0ibres
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Contraction o! "uscle 0ibres
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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Contraction o! "uscle 0ibres
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! "uscle 0ibres
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Contraction o! " scle 0ibres
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Contraction o! "uscle 0ibres
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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Contraction o! "uscle 0ibres
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Contraction o! "uscle 0ibres
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
o! dead musclesgusbakti12
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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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ExcitationContraction Coupling
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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ExcitationContraction Coupling
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
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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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" t i C t ti
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"sometric Contraction
&"oduces no mo#ement
Used in
& Standin
& Sittin
& &ostu"e
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" t i C t ti
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"sotonic Contraction
&"oduces mo#ement
Used in
& =alin
& Mo#in any pa"t o) the body
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