L60. Muscle

Question 1

Describe the depolarisation/repolarisation curve.

Answer 1

Depolarisation as curve rises above 0, as Na+ channels open.
Repolarisation as curve falls to -70mv as K+ channels open.
Refractory period as the curve falls below -70mv
Curve rises to resting state, where it started.

Question 2

Describe the stages of muscle contraction with regards to the myosin head and actin filament.

Answer 2

1. Myosin head has ADP + Pi attached
2. Pi is released so myosin head can join to actin.
3. The myosin head moves the actin filament.
4. ATP binds to the myosin head so the actin filament is released.
5. The myosin head resumes its relaxed position as the ATP is broken down to ADP + Pi.