Gastric Phase

Definition

The gastric phase is a stage in the digestive process that occurs after food enters the stomach. It involves the secretion of various enzymes and acids that begin the breakdown of food, preparing it for further digestion and absorption in the small intestine.

5 Must Know Facts For Your Next Test

1. The gastric phase is initiated by the presence of food in the stomach, which triggers the release of the hormone gastrin.
2. Gastrin stimulates the parietal cells in the stomach lining to secrete hydrochloric acid (HCl), which creates an acidic environment in the stomach.
3. The acidic environment activates the enzyme pepsin, which begins the breakdown of proteins in the food.
4. The mechanical action of the stomach's contractions, along with the churning of the gastric juice, further breaks down and mixes the food.
5. The gastric phase typically lasts 3-4 hours, during which time the food is gradually emptied from the stomach into the small intestine for further digestion.

Review Questions

• Describe the role of gastrin in the gastric phase of digestion.
  • Gastrin is a hormone produced by G cells in the stomach lining. During the gastric phase, the presence of food in the stomach triggers the release of gastrin, which then stimulates the parietal cells to secrete hydrochloric acid (HCl) and other digestive enzymes. The acidic environment created by the HCl activates pepsin, a key enzyme that begins the breakdown of proteins in the food. This gastric secretion and enzyme activation are crucial steps in the initial digestion that occurs during the gastric phase.
• Explain how the mechanical action of the stomach contributes to the gastric phase.
  • The mechanical action of the stomach, including its contractions and churning motion, plays an important role in the gastric phase of digestion. As the stomach muscles contract, they mix and break down the food, further exposing it to the digestive enzymes and acids present in the gastric juice. This mechanical action, combined with the chemical breakdown, helps to transform the food into a thick, soupy mixture called chyme that can be gradually released into the small intestine for continued digestion and absorption.
• Evaluate the significance of the gastric phase in the overall digestive process.
  • The gastric phase is a critical step in the digestive process, as it initiates the breakdown of food and prepares it for further digestion and absorption in the small intestine. During this phase, the stomach secretes hydrochloric acid and enzymes that create an acidic environment, activate digestive enzymes, and begin the mechanical breakdown of food. This sets the stage for the small intestine to continue the digestive process, allowing the body to effectively extract and utilize the nutrients from the food we consume. The gastric phase is, therefore, a vital component of the body's overall digestive system and plays a crucial role in maintaining proper nutrient absorption and overall health.

Related terms

Gastric Juice: The acidic fluid secreted by the stomach, containing enzymes, hydrochloric acid, and other substances that aid in the digestion of food.

Pepsin: A digestive enzyme found in gastric juice that breaks down proteins into smaller peptides.

Gastrin: A hormone produced by G cells in the stomach that stimulates the secretion of gastric juice, including hydrochloric acid and pepsin.