Question

Skeletal muscle is a. striated. b. under voluntary control. c. multinucleated. d. All of these are correct.

Short answer

Skeletal muscle is striated, under voluntary control, and multinucleated. Therefore, the correct answer is \(d. All\text{ }of\text{ }these\text{ }are\text{ }correct\).

Step-by-step solution

Determine if skeletal muscle is striated

Skeletal muscle is indeed striated, meaning it has a pattern of light and dark bands, formed by the arrangement of actin and myosin filaments. This structured appearance allows the muscle to contract and generate force. So, option 'a' is correct.

Determine if skeletal muscle is under voluntary control

Skeletal muscle is under voluntary control. It means that one can consciously control these muscles to perform actions like walking, talking, lifting objects, etc. So, option 'b' is correct.

Determine if skeletal muscle is multinucleated

Skeletal muscle cells are multinucleated, meaning they have multiple nuclei per cell. This happens because skeletal muscle cells are formed by the fusion of multiple myoblasts. The presence of multiple nuclei enables more efficient muscle function and protein synthesis. So, option 'c' is correct.

Verify if all the given statements are correct

From steps 1 to 3, we have determined that skeletal muscle is striated, under voluntary control, and multinucleated. Therefore, option 'd' must be correct, as all of these characteristics apply to skeletal muscle. In conclusion, the correct answer is: d. All of these are correct.

Key concepts

Striated Muscle

Skeletal muscle is often referred to as striated muscle due to its distinctive appearance. When viewed under a microscope, striated muscle displays alternating bands of light and dark stripes. This pattern is the result of the specific arrangement of two main types of protein filaments: actin and myosin.
Actin is a thin filament, while myosin is thicker, and together they form the essential components for muscle contraction. As these filaments slide past each other, they create the appearance of striations.

• The dark bands, known as A-bands, are areas where actin and myosin overlap.
• The light bands, called I-bands, are regions consisting only of actin filaments.

These striations are crucial for the muscle's ability to contract and relax efficiently, allowing for precise movements. The structured alignment of these filaments is integral to the skeletal muscle's ability to generate force.

Voluntary Muscle Control

Skeletal muscles are known for their ability to be controlled voluntarily, meaning they operate through conscious command. This is unlike cardiac and smooth muscles, which function involuntarily.
The ability to control skeletal muscles allows us to perform a variety of tasks such as walking, running, writing, and speaking. In voluntary muscle control, the brain sends signals through the nervous system, instructing muscles to contract for particular actions.

• The primary regions of the brain involved in voluntary movement are the motor cortex and cerebellum.
• Signals are transmitted via motor neurons, which connect the brain with muscle fibers.

Through training and practice, individuals can enhance their voluntary control over these muscles, increasing precision and strength of movements.

Multinucleated Muscle Cells

Skeletal muscle cells, also known as muscle fibers, are unique because they are multinucleated. This means each cell contains multiple nuclei, in contrast to most other cell types, which typically have just one nucleus.
This multinucleated characteristic arises during muscle development, when several individual cells called myoblasts fuse together to form a single muscle fiber. As a result, each nucleus in a muscle fiber arises from a separate myoblast.

• Having multiple nuclei facilitates higher rates of protein synthesis, necessary for muscle repair and growth.
• The presence of multiple nuclei also allows for efficient management of the large cell volume characteristic of muscle fibers.

This enables skeletal muscles to maintain their structure, carry out repairs, and produce necessary proteins swiftly, ensuring optimal muscle function.