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Why is skeletal muscle called "voluntary muscle"? What is its secret action?
In the human body, various muscle tissues work together to maintain our movements and postures. Among them, skeletal muscle is the most special kind of muscle tissue. Because of its autonomous control characteristics, it is called "voluntary muscle". This article will delve into the basic structure and function of skeletal muscles, and how they perform movements.
Skeletal muscles are mainly attached to bones through tendons, allowing us to perform a variety of activities and maintain postures.
Basic characteristics of skeletal muscle
Skeletal muscle is striated muscle and has distinct striations due to the special arrangement of its fibers. These muscles are voluntary, meaning their contraction can occur under conscious control. Compared with smooth muscle and cardiac muscle, the activity of skeletal muscle does not rely on automatic reactions, but on instructions from the brain and nervous system.
The role of skeletal muscles
The main function of skeletal muscles is to produce movement, and they are essential when performing activities such as walking, running, and jumping. They also stabilize joints and assist the body in maintaining balance and posture. In addition, skeletal muscles will play different roles according to needs when performing various types of exercise. These roles can be further divided into "agonist muscles" and "antagonist muscles."
The agonist muscles, also known as the main propeller muscles, are mainly responsible for initiating movement; while the antagonist muscles can regulate the speed of movement and avoid injuries caused by too fast movements.
Skeletal muscle structure
The structure of skeletal muscle consists of muscle fibers, which are composed of many muscle cells, and each cell has multiple nuclei. This allows skeletal muscles to generate strong force quickly and is suitable for high-intensity exercise. A muscle's stability and strength come primarily from the tendons that connect it to the bones, and from the surrounding connective tissue.
The movement mechanism of skeletal muscles
The movement of skeletal muscles is achieved by signaling from the nervous system. When neurons release neurotransmitters, they activate the muscle fibers connected to them, causing the muscles to contract. The degree and speed of these contractions can change according to the needs of exercise, which is one of the abilities of skeletal muscles to adapt to different exercise environments.
Synergy and antagonism
During exercise, muscles usually do not work independently. Instead, agonist and antagonist muscles often need to work together to achieve precision and efficiency in movement. For example, when bending the arm, the biceps contracts as an agonist muscle, while the triceps acts as an antagonist, helping to stabilize the joint and prevent injury.
This involvement of antagonistic muscles not only improves the safety of the movement, but also makes the movement smoother.
Changes and Adaptability of Skeletal Muscle
During regular exercise, skeletal muscles exhibit adaptive changes. These changes are called muscle hypertrophy, which refers to an increase in muscle size, primarily due to increased muscle fibers or enlargement in size. Conversely, without exercise, muscles undergo atrophy, a condition called muscle atrophy, which refers to a reduction in muscle size.
Conclusion
As a unique voluntary muscle, skeletal muscle can complete various activities by regulating movement. Not only is it the basis for our daily lives, it also plays a key role in sports. In the process of continuous exercise, skeletal muscles demonstrate the ability to adapt and change, allowing us to better understand the mystery of physical activity. After all, how can we make more effective use of the characteristics of skeletal muscles in future sports?
