What happens to the l band and H zone during contraction? Do the lengths of the thick and thin filaments change ?

Explanation

### Step-by-Step Solution:

1. **Understanding Muscle Structure**:
- In a striated muscle, there are different bands and zones: the A-band (where thick filaments are present), the I-band (where thin filaments are present), and the H-zone (the area in the A-band where there are no thin filaments).

2. **Muscle Contraction Mechanism**:
- During contraction, the actin filaments (thin filaments) are pulled towards the center of the A-band. This movement is facilitated by the sliding filament theory, where the thin filaments slide past the thick filaments (myosin).

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