Which muscle can perform a contraction called peristalsis?
Group of answer choices
A smooth muscle
B eye muscles
C skeletal muscle
D cardiac muscle
The correct answer and explanation is:
The correct answer is A) smooth muscle.
Explanation: Peristalsis is the involuntary contraction and relaxation of smooth muscle fibers that move food and liquids along the digestive tract. This process occurs primarily in the esophagus, stomach, and intestines, where smooth muscle contractions push contents through the digestive system. Smooth muscle is uniquely suited for this function due to its ability to contract slowly and rhythmically over extended periods without tiring.
Smooth muscle fibers are non-striated, meaning they lack the distinct banding pattern seen in skeletal muscle. These muscles are controlled by the autonomic nervous system and do not require conscious thought or control, unlike skeletal muscles, which are voluntarily controlled. In the case of peristalsis, smooth muscle contractions occur in a coordinated, wave-like pattern that helps propel food through the digestive system.
The contractions begin when the smooth muscle in a section of the digestive tract contracts, pushing the contents forward. As this happens, the muscle behind the food relaxes, allowing the contents to move smoothly into the next segment. This coordinated action continues throughout the digestive tract, facilitating the movement of food, liquids, and waste.
While other muscles like cardiac muscle are also involuntary, they do not perform peristalsis. Cardiac muscle, for example, is specialized for pumping blood and operates in a different mechanism involving rhythmic contractions to maintain circulation. Skeletal muscle, on the other hand, is voluntary and is responsible for moving bones and maintaining posture, not for peristaltic motion. Similarly, eye muscles are also voluntary muscles that control eye movement but do not perform peristalsis.
In summary, peristalsis is a key function of smooth muscle, which is essential for the digestive system’s ability to process food and waste efficiently.