Gastrin

Definition

Gastrin is a hormone produced by the G cells in the stomach that stimulates the secretion of gastric acid, which is essential for digestion. This hormone plays a critical role in regulating gastric motility and the overall digestive process, ensuring that food is properly broken down and nutrients are effectively absorbed. Gastrin levels rise in response to food intake, particularly proteins, and this surge facilitates the digestive activities in the stomach.

5 Must Know Facts For Your Next Test

1. Gastrin is primarily released in response to food entering the stomach, especially proteins, which trigger the G cells to secrete this hormone.
2. Once released, gastrin stimulates parietal cells in the stomach lining to produce more gastric acid, aiding in digestion.
3. In addition to promoting acid secretion, gastrin enhances gastric motility, helping to mix food with digestive juices and move it along the digestive tract.
4. There are three forms of gastrin: gastrin-34, gastrin-17, and gastrin-14, each differing slightly in their structure and physiological roles.
5. Abnormal levels of gastrin can lead to digestive disorders, such as Zollinger-Ellison syndrome, characterized by excessive gastric acid production.

Review Questions

• How does gastrin contribute to the digestive process after food intake?
  • Gastrin plays a vital role in the digestive process by stimulating the secretion of gastric acid from parietal cells in the stomach when food enters. This acid is crucial for breaking down food particles and creating an optimal environment for digestive enzymes to function. Additionally, gastrin increases gastric motility, allowing for better mixing of food with digestive juices, which further aids in digestion and nutrient absorption.
• What are the potential consequences of abnormal gastrin levels in the body?
  • Abnormal gastrin levels can lead to various digestive issues. For instance, excessively high gastrin levels may result in conditions like Zollinger-Ellison syndrome, where excessive gastric acid is produced, leading to ulcers and gastrointestinal discomfort. Conversely, low levels of gastrin can hinder proper digestion due to insufficient gastric acid production, potentially resulting in malabsorption of nutrients. These imbalances can significantly affect overall digestive health and nutrient uptake.
• Evaluate the interactions between gastrin and other hormones involved in digestion, such as cholecystokinin and secretin.
  • Gastrin interacts closely with other hormones like cholecystokinin (CCK) and secretin to coordinate a balanced digestive response. While gastrin primarily stimulates gastric acid secretion and motility in the stomach, CCK promotes the release of digestive enzymes from the pancreas and bile from the gallbladder when fats and proteins enter the small intestine. Secretin, on the other hand, regulates bicarbonate production to neutralize gastric acid entering the small intestine. Together, these hormones ensure that digestion occurs efficiently across different stages while maintaining an optimal environment for enzymatic action.

Related terms

Gastric Acid: A digestive fluid composed mainly of hydrochloric acid, secreted by parietal cells in the stomach lining, that helps break down food and kill bacteria.

Cholecystokinin (CCK): A hormone released by the small intestine that stimulates the digestion of fats and proteins by promoting the release of digestive enzymes from the pancreas.

Pepsinogen: An inactive enzyme secreted by the stomach that is converted into pepsin in the presence of gastric acid, playing a key role in protein digestion.