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Which muscles work automatically under control of the autonomic nervous system?
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muscle
The structure of striated, or skeletal, muscle. Striated muscle tissue, such as the tissue of the human biceps muscle, consists of long fine fibers, each of which is in effect a bundle of finer myofibrils. Within each myofibril are filaments of the proteins myosin and actin; these filaments slide past one another as the muscle contracts and expands. On each myofibril, regularly occurring dark bands, called Z lines, can be seen where actin and myosin filaments overlap. The region between two Z lines is called a sarcomere; sarcomeres can be considered the primary structural and functional unit of muscle tissue.
The muscles that operate automatically under the control of the autonomic nervous system are smooth muscle and cardiac muscle.12
These tissues are classified as involuntary muscles because they function without conscious effort or voluntary control to maintain homeostasis and essential bodily processes.132
- Smooth muscle: Found in the walls of hollow organs and structures such as the stomach, intestines, urinary bladder, and blood vessels, this muscle type is critical for the functioning of the cardiovascular, respiratory, gastrointestinal, and reproductive systems.42
- Cardiac muscle: This tissue makes up the mass of the heart and is responsible for the rhythmic contractions required to pump blood throughout the body.12
The autonomic nervous system regulates these muscles through two primary, often antagonistic, divisions: the sympathetic nervous system and the parasympathetic nervous system.51