What controls the rate of transfer contents stomach into small intestine?
The rate at which contents are transferred from the stomach into the small intestine is controlled by several factors, including:
1. Stomach distension: The stretching of the stomach wall triggers the release of hormones such as gastrin, which stimulates gastric secretions and increases the tone of the pyloric sphincter. This prevents the premature emptying of stomach contents into the small intestine.
2. Acidification of stomach contents: The presence of hydrochloric acid in the stomach helps to break down food particles and create a acidic environment. This acidity stimulates the release of gastrin and inhibits the release of cholecystokinin (CCK), a hormone that promotes gallbladder contraction and relaxation of the pyloric sphincter.
3. Neural reflexes: The vagus nerve plays a crucial role in regulating the rate of gastric emptying. When the stomach is distended or its contents become acidic, the vagus nerve sends signals to the brain, which in turn stimulates the release of gastric inhibitory peptide (GIP). GIP inhibits gastric motility and slows down gastric emptying.
4. Hormonal regulation: The hormone gastrin, as mentioned above, stimulates gastric secretions and increases the tone of the pyloric sphincter. CCK, released in response to the presence of fats and proteins in the small intestine, also inhibits gastric emptying. Secretin, another hormone produced by the small intestine, further inhibits gastric emptying and stimulates the secretion of pancreatic juices.
5. Motilin: Motilin is a hormone that regulates the cyclic contractions of the stomach and small intestine. It promotes gastric emptying by increasing the frequency and amplitude of gastric contractions.
These factors work together to ensure that the transfer of stomach contents into the small intestine is synchronized with the digestive processes occurring in the small intestine and that the appropriate pH and nutrient composition are maintained for optimal absorption.