Question

Gastrin is secreted from G cells located in the antrum of the stomach. One function of gastrin is to A. promote fat digestion and absorption. B. inhibit gastric emptying. C. promote secretion of pancreatic and biliary HCO3 - . D. stimulate gastric mucosa growth.

Short answer

Option D: Stimulate gastric mucosa growth.

Step-by-step solution

- Identify where gastrin is secreted from

Gastrin is secreted from G cells located in the antrum of the stomach.

- Understand the primary functions of gastrin

Gastrin primarily increases gastric acid secretion, helps in gastric mucosa growth, and also increases gastric motility. Other functions include stimulating the release of histamine from enterochromaffin-like cells.

- Analyze the options provided

Option A mentions promoting fat digestion and absorption, which is not a primary function of gastrin. Option B talks about inhibiting gastric emptying; however, gastrin actually promotes gastric motility. Option C suggests promoting secretion of pancreatic and biliary HCO3-, which is mainly stimulated by secretin, not gastrin. Option D mentions stimulating gastric mucosa growth, which is a known function of gastrin.

- Choose the correct answer

Based on the analysis, the correct answer is option D: Stimulate gastric mucosa growth.

Key concepts

Gastric Acid Secretion

Gastric acid secretion is a crucial process in the digestive system. It primarily involves the release of hydrochloric acid (HCl) from the parietal cells located in the lining of the stomach. Gastrin plays a pivotal role in this process.

Gastrin is released from G cells found in the antrum, the lower part of the stomach. Once released, gastrin enters the bloodstream and travels to parietal cells, stimulating them to secrete HCl. The acid aids in breaking down food, activating digestive enzymes, and providing a defense against pathogens.

The secretion of gastric acid is tightly regulated through a feedback mechanism. When enough acid is present, the production of gastrin is reduced, preventing excess acid production. Conversely, when gastric acid levels are low, more gastrin is secreted to boost acid levels. This balance is essential for optimal digestion.

Gastric Mucosa Growth

Gastrin also plays an essential role in the growth and maintenance of the gastric mucosa. The gastric mucosa is the inner lining of the stomach, consisting of epithelial cells that secrete mucus, enzymes, and acids.

Gastrin stimulates the growth of these epithelial cells, ensuring that the gastric mucosa remains healthy and capable of performing its functions. This growth is vital for the continuous replacement of the epithelial layer, which undergoes constant wear and tear.

Maintaining a healthy gastric mucosa is crucial for protecting the stomach lining from the corrosive effects of the acidic environment. It also ensures that the stomach can effectively secrete the necessary substances for digestion. If the gastric mucosa is compromised, it can lead to ulcers and other gastrointestinal issues.

Gastric Motility

Gastric motility refers to the contractions of the stomach muscles that help mix and propel food through the digestive tract. Gastrin significantly influences this process.

When gastrin is secreted, it increases the muscle contractions of the stomach, aiding in the mechanical breakdown of food. This motility ensures that food is adequately mixed with gastric juices, enhancing digestion and preparing the food for movement into the small intestine.

Enhanced gastric motility from gastrin secretion also helps in the timely delivery of partially digested food to the small intestine. This process is known as gastric emptying. Proper gastric motility is vital for efficient digestion and nutrient absorption.

G Cells

G cells are specialized cells located in the antrum of the stomach, and they play a key role in the digestive process by secreting gastrin. These cells are primarily stimulated by the presence of food, particularly proteins. When proteins enter the stomach, G cells detect this and release gastrin.

Gastrin then carries out various functions, such as stimulating gastric acid secretion, promoting gastric mucosa growth, and increasing gastric motility. This hormone ensures that the digestive environment in the stomach is optimal for breaking down food and absorbing nutrients.

Without the proper function of G cells, the regulation of gastric activities would be compromised, leading to digestive issues such as hypochlorhydria (low stomach acid) or hyperchlorhydria (high stomach acid), both of which can affect overall health significantly.