CHAPTER 9- Physiology Anf Skeletal, Cardiac and Smooth Muscle

7/23/2019 CHAPTER 9- Physiology Anf Skeletal, Cardiac and Smooth Muscle

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CHAPTER 9: CELLULAR PHYSIOLOGY OFSKELETAL, CARDIAC AND SMOOTH MUSCLE

Muscle:

Primr! "u#c$i%#: &e#er$e "%rce %r

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•

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• As (um( ssis$i#& re$ur# %"

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• Mus$ +e +le $% mi#$i#

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+l%%- $% lu#&s #- $issues

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ALL MUSCLES $r#s-uce c)emicl e#er&!

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SKELETAL MUSCLE

Contraction of skeletal muscle in initiated by motorneurons that innervate motor units

7Muscle "i+er %r m!%"i+er: smlles$ c%#$rc$ile #i$ %"s*ele$l muscle mul$i#ucle$e-, el%#&$e- cell/7Fscicle: +u#-le %" li#erl! li&#e- muscle "i+ers

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risi#& $)e mem+r#e (%$e#$il $% "iri#& $)res)%l-

AP propaate from the sarcolemma to the interior ofmuscle fibers alon the T! tubule net"ork

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5



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6



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7



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c$i%# (%$e#$il, i#c$i'$e sl%.l!353 T)e re(%lri1$i%# ()se %" $)e c$i%#

(%$e#$il reVec$s $)e -el!e- c$i'$i%# %"

'%l$&e7&$e- K6 c)##els #-, i# s%me cses,

C567c$i'$e- K6 c)##els3 I# s%me u#i$r! sm%%$) muscle, re(%lri1$i%# is

s% -el!e- $)$ $)e c$i%# (%$e#$il c%#$%ur

-is(l!s (r%mi#e#$ (l$eu3

Some smooth muscle cells can initiate spontaneous

electrical activity

$)is s(%#$#e%us c$i'i$! resul$s "r%m (cem*e

curre#$s I# %$)er sm%%$) muscle cells, s(%#$#e%us

elec$ricl c$i'i$! resul$s i# re&ulr, re(e$i$i'e

%scill$i%#s i# >m/ T)ese >m/ %scill$i%#s

%ccur $ "reue#c! %" se'erl %scill$i%#s (er

mi#u$e #- re re"erre- $% s slo" "aves

Some smooth muscles contract "ithout action

potentials

>m/ %scill$i%#s c# le- $% $%#ic c%#$rc$i%#s i#

$)e +se#ce %" c$i%# (%$e#$ils3

;n smooth muscle. both e3tracellular andintracellular Ca%& activate contraction

Sm%%$) muscle cells use $)ree m%r ($).!s

"%r (r%-uci#& $)e rise i# <C56=i $)$ $ri&&ers

c%#$rc$i%#3 C56 e#$r! $)r%u&) '%l$&e7&$e- c)##els

i# res(%#se $% cell -e(%lri1$i%#o ,-e(%lri1$i%# m! (r%-uce # i#V u2 %"

C5653 C56 relese "r%m $)e SRo relese m! %ccur +! ei$)er %" $.%

mec)#isms:

/C567i#-uce- C56 relese

+/IP47me-i$e- C56 relese43 C56 e#$r! $)r%u&) '%l$&e7i#-e(e#-e#$

c)##els3o -e(le$i%# %" C56 s$%res i# $)e SR le-s $%

$)e c$i'$i%# %" s$%re7%(er$e- C56

c)##els SCs/o ;%$) $)e C56 relese "r%m $)e SR #- $)e

e#$r! %" C56 'i SOCs re '%l$&e

8



i#-e(e#-e#$3 (r%'i-e $)e C56 $)$

u#-erlies %#e "%rm %" ()rmc%mec)#icl

c%u(li#&o I# l!m()%c!$es , "ll i# <C56= i#si-e $)e

e#-%(lsmic re$iculum ER/ c$i'$es

(r%$ei# clle- STIM i# $)e ER mem+r#eo STIM, +! -irec$ mec)#icl li#*&e,

c$i'$es (lsm7mem+r#e C56

c)##el clle- Ori, .)ic) i# $ur# me-i$es# u($*e %" C53

o C567relese c$i'$e- C56 curre#$

*#%.# s ;C'AC3

The cross!bride cycle in smooth muscle iscontrolled by phosphorylation of myosin liht chainby myosin liht chain kinase (p1 %<5 7 %*%+

Sm%%$) Muscle

Ac$i# "ilme#$s 7 %rie#$e- mi#l! (rllel %r %+liue $%$)e l%#& 2is %" $)e cell3

De#se +%-ies

7 Mul$i(le c$i# "ilme#$s ((er $% %i# $s(ecili1e- l%c$i%#s i# $)e cell3

- F%u#- imme-i$el! +e#e$) $)e cell mem+r#es .ell s .i$)i# $)e i#$eri%r %" $)e m!%c!$e3

T)ic* "ilme#$s

7 I#$ers(erse- m%#& $)e $)i# "ilme#$s i# sm%%$)muscle3

7 Fr less +u#-#$ $)# i# s*ele$l %r cr-icmuscle3

Sm%%$) MuscleQs Cr%ss7+ri-&e:

7 I# c%m(ris%# $% s*ele$l #- cr-ic muscle, #e#$irel! -i""ere#$ mec)#ism c%#$r%ls cr%ss7+ri-&e$ur#%'er i# sm%%$) muscle3

7 A# i#crese i# <C5=i i#i$i$es sl%. c)i# %"e'e#$s $)$ ul$im$el! i#creses $)e ATPse c$i'i$!%" $)e m!%si#

STEPS:

3 T)e +i#-i#& %" "%ur C56 i%#s $% calmodulin,cl%sel! rel$e- $% $r%(%#i# C %" s$ri$e- muscle3/

53 C5Z7CM c%m(le2 c$i'$es # e#1!me *#%.#s myosin liht chain kinase (MLCK+3P)%s()%r!l$es $)e re&ul$%r! li&)$ c)i# $)$ isss%ci$e- .i$) $)e m!%si# II m%lecule3/

43 P)%s()%r!l$i%# %" $)e li&)$ c)i# l$ers $)ec%#"%rm$i%# %" $)e m!%si# )e-3 Gre$l!i#creses i$s ATPse c$i'i$! #- ll%.s i$ $%i#$erc$ .i$) c$i# #- $% c$ s m%leculrm%$%r3/

B3 P)%s()%r!l$i%# l$ers $)e c%#"%rm$i%# %"m!%si# )e-, .)ic) i#clu-es i$s ATPse c$i'i$!#- i#$erc$ .i$) c$i#3

T.% (r%$ei#s $%#icll! i#)i+i$ $)e i#$erc$i%# +e$.ee#c$i# #- m!%si#3

Cl(%#i#

7 F%u#- i# $r%(%m!%si# #- c$i#

7 T%#icll! i#)i+i$s $)e ATPse c$i'i$! %" m!%si#3

7 S$%ic)i%me$r! .i$) $r%(%m!%si# #- c$i#: %#ecl(%#i# %#e $r%(%m!%si#7 se'e# c$i#m%#%mers/3

T.% e""ec$s %# cl(%#i# ;%$) e""ec$s re-ucecl(%#i#Qs i#)i+i$i%# %" m!%si#Qs ATPse c$i'i$!/

3 C567CM +i#-s $% cl(%#i#353 C567CM c$i'$es C567CM-e(e#-e#$

(r%$ei# *i#se, .)ic) ()%s()%r!l$escl(%#i#3

Cl-esm%#

7 T%#icll! i#)i+i$s $)e c$i#7c$i'$e- ATPsec$i'i$! %" m!%si# i# sm%%$) muscle3

7 C%#$i#s +i#-i#& -%mi# "%r c$i#, m!%si#,$r%(%m!%si# #- C7CM3

7 ;l%c* $)e i#$erc$i%# %" c$i# .i$) m!%si#3

Termination of smooth muscle contraction

7 Rel2$i%# %" sm%%$) muscle reuires m!%si# li&)$c)i# MLC/ -e()%s()%r!l$i%#, .)ic) is cc%m(lis)e-+! myosin liht chain phosphatase3

9



He$er%$rimer:

- su+u#i$s .i$) m%leculr msses %" 4, 5, #-4 *D3

7 T)e 47*D su+u#i$ c%#"ers s(eci"ici$! +!+i#-i#& $% m!%si#7 T)e 47*D is $)e c$l!$ic su+u#i$ res(%#si+le"%r $)e -e()%s()%r!l$i#& c$i'i$!3

Smooth muscle contraction may also occurindependently of increases in ,Ca%6-i

- m%-ul$es $)e c$i'i$! %" c%#$rc$ile %r re&ul$%r!(r%$ei#s -irec$l!, $)us, $)e m%u#$ %" "%rce-e'el%(e- $ #! &i'e# <C56=i m! 'r!3

- C567i#-e(e#-e#$ c%#$rc$i%#s m! resul$ ei$)er "r%m # i#crese i# $)e r$e %" MLC()%s()%r!l$i%# +! MLCK %r "r%m -ecrese i#$)e r$e %" MLC -e()%s()%r!l$i%# +! MLC()%s()$se3

P)rmc%mec)#icl c%u(li#& e&3 c(+le %" i#i$i$i#&

sm%%$) muscle c%#$rc$i%# +! i#-uci#& IP47me-i$e-relese %" C56

;n smooth muscle. contractile force is enhanced byincreasin the entry of Ca%6 as "ell as by increasinthe Ca%6 sensitivity of the contractile apparatus

C%#$rc$ile "%rce %" sm%%$) muscle

- C# mi#$i# sus$i#e- c%#$rc$i%# $)$ c#+e &r-e- i# s$re#&$) %'er .i-e r#&e3

- De(e#-s %# $)e rel$i'e +l#ce +e$.ee# $)e()%s()%r!l$i%# #- -e()%s()%r!l$i%# %"

MLCs3- T)e r$e %" MLC ()%s()%r!l$i%# is re&ul$e- +!

$)e C567CM c%m(le2, .)ic) i# $ur# -e(e#-s%# levels of intracellular Ca2 63

i-er r#&e $)# i# s*ele$l #- cr-ic muscle:

s$ 7 D% #%$ &e#er$e c$i%# (%$e#$ils3 R$)er, $)eirmem+r#e (%$e#$il 'ries sl%.l! i# res(%#se $%#eur%$r#smi$$ers %r )%rm%#es3

5#- 7 Relese %" C56 "r%m i#$rcellulr s$%res m! +em%-ul$e- $)r%u&) #eur%$r#smi$$er7i#-uce- &e#er$i%#

%" i#$rcellulr sec%#- messe#&ers suc) s IP43

Le'el %" c%#$r%l %'er c%#$rc$ile "%rce +! re&ul$i#& C56se#si$i'i$! %" (r%$ei#s:

3 Re&ul$i#& $)e Ca%& sensitivity of proteins $)$ re&ul$e c%#$rc$i%#3

E2m(le:i#)i+i$i#& myosin light chain phosphatase l$ers$)e +l#ce +e$.ee# ()%s()%r!l$i%# #-

-e()%s()%r!l$i%#, i# e""ec$ ll%.i#& &re$erc%#$rc$i%# $ l%.er <C56=i3

53 Al$er$i%# %" $)e C56 se#si$i'i$! %" $)e m!%si#li&)$ c)i# *i#se3

E2m(le: MLCK i$sel" is ()%s()%r!l$e- $ s(eci"ic si$es+! se'erl (r%$ei# *i#ses, i#clu-i#& PKA, PKC, #-C567CM-e(e#-e#$ *i#ses3 P)%s()%r!l$i%# +! #!%" $)ese *i#ses -ecreses $)e se#si$i'i$! %" MLCK $%c$i'$i%# +! $)e C567CM c%m(le23

Smooth muscle maintains hih force at lo" eneryconsumption

Latch state

- L%. e#er&! c%#sum($i%# )i&) $e#si%# r$e- Hi&) $e#si%# c# +e mi#$i#e- -es(i$e $)e

-ecrese i# $)e -e&ree %" muscle c$i'$i%# +!e2ci$$%r! s$imuli3

- F%rce is mi#$i#e- $ l%.er le'el %" MLCK()%s()%r!l$i%#3

#;>E'S;TD AM2 MUSCLES

Ec) muscle $!(e s*ele$l, cr-ic, #- sm%%$)/ is-is$i#&uis)+le %# $)e +sis %" i$s u#iue )is$%l%&!, ECc%u(li#& mec)#isms, #- re&ul$i%# %" c%#$rc$ile"u#c$i%#3 Re"er $% $)e %$)er (&e "%r $)e $+le %r i# $)e+%%* $+le 97

Skeletal muscle is composed of slo"!t"itch andfast!t"itch fibers (refer to the table on the otherpaper or on the book table F!%+

Sl%.7$.i$c) "i+ers T!(e I/

- &e#erll! $)i##er #- )'e -e#ser c(illr!#e$.%r* surr%u#-i#& $)em3

- T)ese type ; "i+ers ls% ((er re- +ecuse %" lr&e m%u#$ %" $)e %2!&e#7+i#-i#& (r%$ei#myolobin1

- F'%rs %2i-$i'e me$+%lism +ecuse i$ )s l%.&l!c%&e# c%#$e#$ #- &l!c%l!$ic e#1!me c$i'i$!+u$ ric) mi$%c)%#-ril #- %2i-$i'e e#1!mec%#$e#$3

Fs$7$.i$c) "i+ers T!(e II/

- Rel! %# %2i-$i'e me$+%lism type ;;a/ #- reui$e similr $% sl%.7$.i$c) "i+ers .i$) res(ec$ $%m!%&l%+i# c%#$e#$3

- Fs$7$.i$c) %2i-$i'e "i+ers c%#$i# +u#-#$&l!c%&e# #- )'e &re$er #um+er %"mi$%c)%#-ri $)# sl%.7$.i$c) "i+ers -%3

- E#sure -eu$e ATP &e#er$i%# $% c%m(e#s$e"%r $)e i#crese- r$e %" ATP )!-r%l!sis i# "s$7$.i$c) "i+ers3

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Fs$7$.i$c) "i+ers T!(e II+/

- Fe.er mi$%c)%#-ri #- l%.er c%#ce#$r$i%#s %"m!%&l%+i# #- %2i-$i'e e#1!mes3

- T)ese "i+ers re .)i$e -ue $% l%. m!%&l%+i#c%#$e#$3

- Ric)er i# &l!c%l!$ic e#1!me c$i'i$! $)# %$)er"i+er $!(es3

-

F%ur is%"%rms %" $)e MHC (r%$ei# re e2(resse- i#s*ele$l muscle MHC , MHC II, MHC II+, MHC II2-/3

- S%me "i+ers e2(ress c%m+i#$i%# %" $.%-i""ere#$ is%"%rms, $)ese )!+ri- cells )'e r$es%" c%#$rc$i%# $)$ re i#$erme-i$e +e$.ee# $)e$.% (ure "i+er $!(es3

Di""ere#ces i# $)e r$es #- s$re#&$) %" c%#$rc$i%#:(table 9-1)

7 Resul$s "r%m -i""ere#ces i# myosin liht chain is%"%rme2(ressi%#

7 Is%"%rm -i""ere#ces m%#& %$)er c%m(%#e#$s %" $)e ECc%u(li#& (r%cess3

T)ree skeletal muscle isoforms )'e +ee# i-e#$i"ie-:(table 9-1)

7 MLC!@as and MLC!@bs re e2(resse- i# sl%.7$.i$c)"i+ers, .)eres MLC!@f and MLC! Gf re e2(resse- i#"s$7$.i$c) "i+ers3

Is%"%rm -i""ere#ces ls% e2is$ "%r $)e S' Ca%6 pump:

(table 9-1)

7 Clseues$ri#, $)e C567relese c)##el, #- $r%(%#i#C3 Fur$)erm%re, s%me (r%$ei#s, suc) s()%s()%lm+#, re e2(resse- i# %#e " i+er $!(e sl%.$.i$c)/ #- #%$ $)e %$)er3

The properties of cardiac cells vary "ith location inthe heart

- Fu#c$i%#l -i""ere#ces m! e2is$ +e$.ee#

muscle cells #er $)e sur"ce %" $)e )er$epicardial cells/ #- $)%se li#i#& $)e i#$eri%r %"$)e sme c)m+ers endocardial cells/3

- T)e MHC i# )er$, "%r e2m(le, e2is$s i# $.%is%"%rms, l() #- +e$ .)ic) m! +ee2(resse- l%#e %r i# c%m+i#$i%#3

Smooth muscle cells may differ markedly amontissues and may adapt their properties "ith timeeven in a sinle tissue

7 E'e# m%#& sm%%$) muscle cells .i$)i# $)e sme s%r$%" $issue, im(%r$#$ "u#c$i%#l -i""ere#ces m! e2is$3

E2m(le: 'sculr sm%%$) muscle cells .i$)i# $)e .lls%" $.% r$eri%les $)$ (er"use -i""ere#$ %r&#s m! 'r! i#$)eir c%#$rc$ile res(%#se $% 'ri%us s$imuli3 Di""ere#cesm! e'e# e2is$ +e$.ee# 'sculr sm%%$) muscle cells $$.% -i""ere#$ (%i#$s l%#& %#e r$eril ($).!3

7 T)e ()e#%$!(e %" sm%%$) muscle .i$)i# &i'e# %r&#m! c)#&e .i$) s)i"$i#& -em#-s3

E2m(le: T)e u$erus, "%r e2m(le, is c%m(%se- %"sm%%$) muscle$)e m!%me$rium$)$ u#-er&%esremr*+le $r#s"%rm$i%# -uri#& &es$$i%# s i$(re(res "%r (r$uri$i%#

7 T)is 'rie$! is resul$ %" +%$) mul$i(le &e#es #-l$er#$i'e s(lici#&3

Smooth muscle cells e3press a "ide variety ofneurotransmitter and hormone receptors

Summr! c%m(ris%# +e$.ee# muscle $!(es is(rese#$e- i# T+le 9743

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Fi& 9793 Is%me$ric #- is%$%#ic c%#$rc$i%#s3

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CHAPTER 9- Physiology Anf Skeletal, Cardiac and Smooth Muscle

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Transcript of CHAPTER 9- Physiology Anf Skeletal, Cardiac and Smooth Muscle