Peristalsis is best described as which of the following?

• A. Voluntary movement
• B. Tonic contractions
• C. Rhythmic wave-like contractions
• D. Passive diffusion

Answer: (C)

Peristalsis describes rhythmic wave-like contractions of the smooth muscle in the walls of the digestive tract that propel contents forward. These contractions are involuntary, driven by the autonomic and enteric nervous systems, not by conscious control. They work by coordinating circular and longitudinal muscle actions so a constriction behind the bolus squeezes it forward, creating a wave that moves along the gut. This is different from tonic contractions, which are sustained and don’t produce propulsion, and from passive diffusion, which is a passive movement driven by concentration gradients rather than muscle activity. So peristalsis is best described as rhythmic wave-like contractions that push material forward along the digestive tract, such as moving a swallowed piece of food toward the stomach.