contração muscular - .• separação de cromossomas • dineína – usa os microtúbulos como
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Contrao muscular
Motores moleculares
Miosina
Usa a actina como substrato.
Miosinas II: conrtao muscular
Miosinas V: transporte de organelas
Kinesina
Usa os microtbulos como substrato.
Transporte axonal antergrado
Separao de cromossomas
Dinena
Usa os microtbulos como substrato.
Transporte axonal retrgrado
Movimentos de clios e flagelos
Motores moleculares usam a energia livre da
hidrlise do ATP para gerarem conformaes
moleculares que levam ao movimento
O msculo estriado
esqueltico
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-14/figure-14-2https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-14/figure-14-2A juno neuromuscular uma sinapse do tipo 1 para 1ou seja: 1 potencial de ao pr-sinptico causa 1 potencial de ao
muscular
A unidade motora compreende o nervo motor
mais as fibras que ele inerva
Cada fibra recebe um
terminal.
O tamanho da unidade
motora depende da
funo do msculo.
A unidade motora a
unidade geradora de
fora do msculo
A unidade motora compreende o nervo motor
mais as fibras que ele inerva
Rectus lateralis = 5
Masseter = 640
Gastrocnemius = 1800
O sarcmero
O sarcmero relaxado e
contrado
- https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-14/figure-14-8https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-14/figure-14-8
Principais protenas do sarcmero do
msculo esqueltico
A formao da ponte cruzada e o ciclo
do ATP
Msculo relaxado
Msculo contrado
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-14/figure-14-9https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-14/figure-14-9Contrao do sarcmero1. Despolarizao da membrana ps-sinptica, sarcolema e tbulos T
2. Mobilizao de Ca2+
3. Ao do Ca2+ nos mecanismos regulatrios miofibrilares
Acoplamento excitao-contrao
O que ?
Mecanismo por qual o sinal eltrico (potencial
de ao) se converte em uma ao mecnica
(contrao).
Para isso precisamos de um segundo
menssageiro qumico:
Clcio!
Mecanismos de acoplamento
A contrao do msculo esqueltico
depende da despolarizao do sarcolema Sensor de potencial
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-1https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-1Mecanismos de acoplamento no msculo
esqueltico
Os tubulos T e a cisterna terminal
esto em contato ntimo,
formando as trades
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-5https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-5O sensor de voltagem um canal de clcio (receptor de DHP) acoplado a
um canal de clcio do retculo sarcoplasmtico (receptor de rianodina)
O acoplamento EC no msculo esqueltico
mecnico
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-7https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-7A Ca-ATPase reticular (SERCA) retorna
o clcio sarcoplasmtico aos nveis
basais
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-8https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-8A hipertermia maligna uma doena
gentica do receptor de rianodina que
desacopla a contrao da excitaoO RyR desses pacientes possui mutaes que conferem
sensitividade a anestsicos volteis como o halotano
Ensaio feito com msculo esqueltico de um paciente com hipertermi malignaUCLA Department of Anesthesiology
Mecnica da contrao do
msculo esqueltico
Representao mecnica do
msculo
Matriz extracelular, sarcolemas vizinhos, ceitoesqueleto
tendes
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/ch16-figure-text-01-ahttps://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/ch16-figure-text-01-aA contrao do msculo esqueltico (twitch) acontece 30 a 40 ms aps o
pico do potencial de ao e controlada pelo aumento do clcio
Um nico AP libera clcio suficiente para saturar seus stios nas troponinas, porm
de forma rpida
A fora mxima gerada pelo msculo esqueltico
depende do intervalo da resposta de estmulos
consecutivos
Ttano
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-2https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-2Medindo a relao entre fora e comprimento
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-3https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-3https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-4https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-4Contrao isomtrica e isotnica
A fora de contrao isomtrica depende da quantidade de
sobreposio entre os filamentos espessos e finos
Tenso passiva = fora necessria para esticar o msculo relaxado
Tenso total = tenso isomtrica mxima de um msculo em determinado comprimento
Tenso ativa = diferena entre a tenso total do msculo contrado e a tenso passiva
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-5https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-5A velocidade da
contrao isotnica
decai com o aumento
da fora (load)
aplicada
Vo = velocidade maxima (atividade mxima de
formao de pontes cruzadas)
Fo = fora mxima produzida pelo msculo
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-6https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-6https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-7https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-7Existem 3 tipos de msculos esquelticos
FF = Rpidos fatigveis (tipo I)
FR = Rpidos resistentes (tipo II)
S = Sustentados (tipo II)
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-9https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/figure-16-9https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/ch16-figure-text-01-bhttps://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-16/ch16-figure-text-01-bDiferenas entre as fibras
Property White muscles (I) Red muscles (II)
Twitch contraction time,
msec
Fast, 50-80 Slow, 100-200
Minimum tetanic
frequency
60/sec 16/sec
Myoglobin content Low High
Primary source of ATP Glycolysis Oxidative
phosphorylation
Glycogen High Low
Myosin-ATPase activity High Low
Capillary blood flow Low High
Fatiguability Easy Difficult
Nerve fiber size Large Small
Nerve fiber activity Intermittent, high
frequency
Continuous, low frequency
Tension produced Larger Smaller
O Msculo estriado cardaco
O acoplamento no msculo cardaco
qumico, envolvendo a libera de clcio
induzida pelo clcio
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-10https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-10O clcio no msculo cardaco expulso tanto pela SERCA
como por mecanismos de membrana.
https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/chapter-15/figure-15-9https://studentconsult.inkling.com/read/cellular-physiology-and-neurophysiology-blaustein-kao-matteson-2nd/