Voluntary vs Involuntary Muscles
The moving ability is essential for many organisms, and that is made possible by the muscular system. The main responsibilities of muscles are body movement, maintaining the body posture and shape, and maintaining body temperature. In human, muscles comprise nearly half of the whole body weight. Human body contains over 650 different muscles, and most of them are attached to bones. Depending on the movements and structure, there are three main types of muscles; namely, skeletal muscles, smooth muscles, and cardiac muscles. These three types can be put into two main categories of muscles; involuntary and voluntary, depending on their control mechanisms. Here, the cardiac and smooth muscles are considered as involuntary muscles, while skeletal muscles are considered as voluntary muscles.
Voluntary Muscles
Voluntary muscles are the muscles that can be controlled consciously, and are made up of cylindrical fibres. Generally, these muscles are attached to bones of the skeleton, thus called the skeletal muscles. Skeletal muscles are striated and are made up of multinucleate cells. Each cell is referred to as muscle fiber. The cell membrane of muscle fiber is known as sarcolemma, and the cytoplasm is called sarcoplasm. The strength of voluntary muscles can be improved by regular exercises and improving muscular endurance. Involuntary muscles help to move certain body parts like limbs, head, eyelids, etc in organisms. Other than that, they help to maintain body temperature and body postures.
Involuntary Muscles
Involuntary muscles are the muscle that cannot be controlled consciously. Their actions are mainly controlled by the autonomic nervous system in the body. Main types of involuntary muscles are smooth muscles and cardiac muscles. Smooth muscles are visceral and are found in the internal walls of the stomach, intestines, uterus, and blood vessels. They help to push food along the length of the alimentary canal, contract the uterus during labor and childbirth, and control the internal diameter of the blood vessels. Cardiac muscles are unique and are found only in the heart. These muscles help to maintain the blood circulation throughout the body by maintaining heart beat.
What is the difference between Voluntary and Involuntary Muscles?
• Voluntary muscles are associated with nerves under voluntary control, whereas involuntary muscles are associated with nerves of autonomic nervous system which is under involuntary control.
• Unlike involuntary muscles, voluntary muscles can be controlled consciously.
• Contractions of voluntary muscles may be rapid and forceful, whereas that of involuntary muscles are rhythmic and slow.
• Smooth and cardiac muscles are considered as involuntary muscles, whereas skeletal muscles are considered as voluntary muscles.
• Voluntary muscles contribute a high percentage of the total body weight, while involuntary muscles contribute the rest.
• Unlike involuntary muscles, voluntary muscles are attached to bones. Involuntary muscles are visceral.
• Voluntary muscle tissue is made up of cylindrical fibres, while involuntary muscles (smooth muscles) are made up of spindle- shaped fibres.