Skeletal Muscle Flashcards
What does tropomyosin do?
- helps stabilise actin filaments
- covers the myosin binding sites in resting state
What does troponin do?
Binds myosin
Which protein are tropomyosin and troponin wrapped around?
Actin
What is present on the myosin heads?
- actin binding site
- ATPase site
How does calcium regulate the cross bride site?
It binds to troponin and moves tropomyosin out of the way so that the myosin head can bind to the actin
Cross bridge cycle
- myosin head attached to actin
- ATP attaches to the myosin head at the active site
- ATP is hydrolysed
- the myosin head repositions
- a phosphate is lost and the head reattached
- ATP is released and the power stroke occurs
Where is Caw+ store in skeletal muscle?
Sacroplasmic reticulum
How does AP signalling work in skeletal muscle?
- AP moves down the t tubule
- depolarisation activates voltage sensors (ligand for calcium channels)
- calcium channels open and calcium floods out
How does Ca2+ get back into the sacroplasmic reticulum?
Ca2+ pumps
What is an isotonic contraction?
Muscle shortens, while load remains constant
What is an isometric contraction?
Muscle develops tension but does not shorten - the load is greater than the force produced
What is a twitch?
The force produced from 1 action potential
What is a tetanus?
The force produced from multiple action potentials
What causes a tetanus?
The un binding of calcium from troponin is slower than the release of calcium - calcium hovers
What causes the length tension relation ship?
Overlapping of actin and myosin fibres
