Topic 6 Muscle Contraction Flashcards
What is the order of the bands?
[In muscle contraction]
I A I
I band A band I band
What colour are the bands?
Dark-a=A bands.
Light-I=I bands.
What is in the middle of I bands?
Z line which is sarcomere
What is the middle of A band?
H Zone.
What filaments are present in A band?
In A band there is Actin and Myosin.
So thick and thin filaments together.
What type of filament is present in I band?
I band has thin filaments only so only actin.
What are the names of the thin and thick filaments?
Thin filaments are Actin.
Thick filaments are Myosin.
What protein in present in Actin Filament?
Tropomyosin
What binding site is in each Myosin head?
Each Myosin head has a binding site for Actin and binding site for ATP
What is the sliding filament Hypothesis?
Thick and thin filaments do not change length.
A bands remain constant (A bands same length)
I bands decrease
Z line move together so sarcomere gets shorter
What is the first thing that occurs in Sliding filament theory?
Action potential arrives at muscle fibre depolarising the Sacrolemma by T-Tubles causing release of Ca2+ from Sacrolemma Reticulm.
What do Ca2+ ions do in Muscle contraction?
Ca2+ bind to tropomyosin which cause to expose myosin head binding site on the actin filament
When Myosin head binds to the binding site on the Actin Filament what is formed?
Actin-Myosin cross bridge formed upon myosin and actin attachment this causes myosin to rotate to centre of Sacrolemma causing power stroke.
What causes Myosin head to detach and what does this do?
ATP is then hydrolysed by ATP hydrolase and causes myosin head to detach and reattach on further binding sites shorting sacromere causing muscle contraction.
When impulse stops in sliding filament theory occurs?
When impulse stops Ca2+ actively transported back into Sacrolemma Reticulm this allows tropomyosin to block myosin head binding sites on Actin Filament