The functional unit of muscle is :

Options

A. Muscle fibre
B. Sarcomere
C. Acini
D. Sutures

Answer

To determine the functional unit of muscle, let's analyze the options provided in the question step by step:

1. **Understanding Muscle Structure**:
- Muscle fibers are the basic building blocks of muscle tissue. They are long, cylindrical cells that contain multiple nuclei and are composed of smaller units called myofibrils.

**Hint**: Recall that muscle fibers are made up of smaller structures, which play a crucial role in muscle contraction.

2. **Evaluating the Options**:
- **Option 1: Muscle Fiber**: While muscle fibers are essential components of muscle tissue, they are not the functional unit. They are made up of myofibrils and are too large to be considered the basic functional unit.

**Hint**: Think about what smaller unit within the muscle fiber is responsible for contraction.

- **Option 2: Sarcomere**: The sarcomere is indeed the functional unit of muscle. It is the segment of a myofibril that contains the actin and myosin filaments, which slide past each other during muscle contraction. This sliding mechanism is what enables muscle contraction and relaxation.

**Hint**: Remember that the sarcomere is defined by its boundaries, known as Z-lines, and is essential for the contraction process.

- **Option 3: Echinacea**: This option is incorrect as Echinacea refers to a genus of flowering plants and is not related to muscle structure.

**Hint**: Consider whether the term relates to muscle anatomy or physiology.

- **Option 4: Sutures**: Sutures are immovable joints found in the skull and are not related to muscle function.

**Hint**: Think about the context of the question and whether the term is associated with muscle tissue.

3. **Conclusion**:
- After evaluating all the options, the correct answer is **Option 2: Sarcomere**, as it is the functional unit of muscle responsible for contraction.

**Final Answer**: The functional unit of muscle is the **Sarcomere**.