What is Z- line? Give its function.

Explanation

### Step-by-Step Solution:

1. **Definition of Z-line**: The Z-line, also known as the Z-disc, is a structure found in the sarcomere, which is the basic contractile unit of muscle tissue. It serves as the lateral boundary of the sarcomere.

2. **Location of Z-line**: The Z-line is located at the ends of the sarcomere. It demarcates the beginning and end of each sarcomere, and the region between two Z-lines constitutes one complete sarcomere.

3. **Composition of Z-line**: The Z-line is associated with thin filaments, specifically actin filaments. These filaments play a crucial role in muscle contraction.

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