Peristalsis is Regulated by the CNS and Enteric Nervous System for Food Movement
- The movement of food through the digestive system is regulated by both voluntary and involuntary control mechanisms.
- Imagine taking a bite of your favorite food.
- As you swallow, the food travels down your esophagus, through your stomach, and into your intestines.
- This journey is powered by peristalsis, a series of muscle contractions that move food through the digestive tract.
Definition
Peristalsis
Peristalsis is a wave-like contraction of smooth muscles that pushes food through the digestive tract.
The Role of the Central Nervous System (CNS)
The CNS, comprising the brain and spinal cord, initiates and controls voluntary actions in the digestive process, such as swallowing and egestion.
1. Swallowing: A Two-Phase Process
- Voluntary Phase: You consciously push food to the back of your mouth using your tongue.
- Involuntary Phase: Once food reaches the pharynx, sensory receptors trigger a reflex controlled by the brainstem, moving food into the esophagus.
Swallowing is a rare example of an action that begins voluntarily but quickly becomes involuntary.
2. Egestion: Voluntary Control of Defecation
- Rectal Filling: As the rectum fills with feces, stretch receptors send signals to the CNS.
- Voluntary Decision: The brain decides whether to relax the external anal sphincter, allowing defecation.
Infants lack voluntary control over defecation, which is why toilet training is necessary.
The Enteric Nervous System (ENS):
Definition
Enteric nervous system
The enteric nervous system, often called the “second brain,” responsible for controlling involuntary muscle contractions in the digestive tract.
- The ENS is a complex network of neurons embedded in the walls of the digestive tract.
- It operates independently of the CNS, controlling involuntary processes like peristalsis.
