Biology · Support and Movement

Smooth muscles do not line the wall of the heart. The heart is lined by cardiac muscle, which has striations and is also controlled by the autonomic nervous system. Smooth muscles are found in the walls of organs such as blood vessels, the digestive tract, and the respiratory system; they lack striations and have spindle-shaped cells.

 Smooth muscles are involuntary and controlled by the autonomic nervous system, which regulates functions without conscious effort, such as digestion and blood vessel constriction.

Smooth muscle cells are elongated, with tapered ends resembling spindles. This shape allows them to pack closely and work efficiently in organs that need to contract in a wave-like motion.

Smooth muscles do not line the wall of the heart. The heart is lined by cardiac muscle, which has striations and is also controlled by the autonomic nervous system. Smooth muscles are found in the walls of organs like blood vessels, the digestive tract, and the respiratory system, and they lack striations and have spindle-shaped cells.

Unlike skeletal and cardiac muscles, smooth muscles lack visible bands or striations because their actin and myosin filaments are arranged differently, giving them a smooth appearance under a microscope. This arrangement suits their role in sustained, slow contractions across various organs.