American Academy of Professional Coders (AAPC) Practice Exam

The contraction of smooth muscle primarily leads to a reduction in the size of the organs in which it is present. Smooth muscle is found in various organs, including the gastrointestinal tract, blood vessels, and the respiratory system. When these muscles contract, they effectively decrease the internal volume of the organ, which can help to facilitate functions such as digestion, blood flow regulation, and airflow to the lungs.

For example, in the gastrointestinal tract, smooth muscle contractions (peristalsis) propel food through the digestive system by pushing it forward, which reduces the size of the lumen (the hollow part of the organ). Similarly, in blood vessels, the contraction of smooth muscle leads to vasoconstriction, which decreases the diameter of the vessel and thus reduces blood flow.

This understanding highlights how the function of smooth muscle contraction is integral to the proper functioning of various organ systems, making the reduction in size the hallmark effect of this muscle activity.