Week 5 - Muscle Contraction Flashcards
What forms striations
Myofibrils are organised in parallel bundles such that their different regions appear as stripes under the microscope.
What is the Z disc
Where adjacent actin filaments join onto eachother
What is the I band
the exposed area of actin filament that is not connected to the myosin
What is the H zone
The exposed myosin filament that is not connected to actin
What is the A band
It extends along the length of the myosin
What is the M line
The line of titin filament
What is the sarcomere
The distance between Z discs (on actin)
When calcium binds, what happens to the sarcomere
It is brought closer together
3 components of actin
troponin, tropomyosin and G actin
4 stages of contraction within the context of the myosin and actin myofibrils
- Myosin cross bridge attaches to actin myofilament (troponin complex).
- Myosin head pivots and bends as it pulls the actin filament towards the M line. ADP and inorganic phosphate released from myosin head (high energy –> low energy myosin head).
- New ATP attaches to myosin head, causing the cross bridge to detach.
- Cocking of the myosin head occurs as ATP is split up into ADP and Pi.
What the name for the specialised endoplasmic reticulum
Sarcoplasmic reticulum
8 steps that lead up to myosin head binding to attachment point on myosin
- Nerve impulse reaches neuromuscular junction.
- Acetylcholine is released from motor neurone.
- Ach binds with receptors in the muscle membrane to allow sodium to enter.
- Sodium influx will generate an action potential in the sarcolemma
- Action potential travels down the T tubule
- Sarcoplasmic reticulum releases calcium
- Calcium binds with troponin to move the troponin-tropomyosin complex.
- Binding sites in the actin filament are exposed, ready for myosin head binding.
Lack of oxygen causes what kind of deficit
ATP deficit
What builds up during anaerobic respiration
Lactic acid
What can
