Gastric motility

Gastric motility refers to the movements of the stomach that enable the mixing and propulsion of stomach contents. It is a crucial aspect of the digestive system, facilitating the mechanical digestion of food and its eventual passage into the small intestine. Gastric motility is regulated by a complex interplay of neural and hormonal factors, which coordinate the muscular contractions of the stomach walls.

Overview

The process of gastric motility involves two main types of movements: peristaltic waves and mixing waves. Peristaltic waves are responsible for moving the stomach contents toward the pylorus, the opening to the small intestine, while mixing waves serve to blend the food with gastric juice, producing a semi-liquid mixture known as chyme.

Regulation

Gastric motility is regulated by the enteric nervous system (ENS), a part of the autonomic nervous system specifically dedicated to the gastrointestinal tract. The ENS works in concert with the central nervous system (CNS), responding to signals from the brain as well as to local stimuli within the stomach. Hormones such as gastrin, cholecystokinin (CCK), and secretin also play significant roles in modulating stomach movements.

Phases of Gastric Motility

Gastric motility can be divided into three phases: the cephalic phase, the gastric phase, and the intestinal phase. Each phase is characterized by specific triggers and responses:

• Cephalic Phase: Triggered by the sight, smell, taste, or thought of food, this phase prepares the stomach for food intake by increasing gastric juice secretion and motility through vagal stimulation.
• Gastric Phase: Begins when food enters the stomach, stretching its walls and activating local and central reflexes that enhance gastric secretion and motility.
• Intestinal Phase: Initiated as chyme enters the small intestine, this phase involves a decrease in stomach motility and secretion, regulated by hormonal feedback mechanisms to ensure proper digestion and absorption in the intestine.

Clinical Significance

Abnormalities in gastric motility can lead to various gastrointestinal disorders, such as gastroparesis, where the stomach empties too slowly, causing nausea, vomiting, and bloating. Conversely, accelerated gastric emptying can result in dumping syndrome, characterized by rapid transit of food into the small intestine, leading to symptoms like diarrhea and abdominal cramps.

Treatment

Treatment for gastric motility disorders typically involves dietary modifications, medications to enhance or inhibit stomach contractions, and, in severe cases, surgical interventions. Understanding and managing these conditions require a comprehensive approach that addresses the underlying causes and symptoms.