Intestinal phase

Definition

The intestinal phase is the third and final stage of gastric secretion and digestion, occurring when chyme enters the small intestine. This phase plays a critical role in regulating digestive processes by coordinating the activities of various hormones and neural signals that promote digestion, absorption, and the movement of food through the intestines.

5 Must Know Facts For Your Next Test

1. During the intestinal phase, secretions from the pancreas and liver are stimulated to aid in further digestion and nutrient absorption.
2. The presence of fatty acids and amino acids in the small intestine triggers the release of hormones like cholecystokinin (CCK) and secretin, which help regulate digestive processes.
3. The intestinal phase helps slow down gastric emptying, ensuring that food is properly mixed with digestive juices before further digestion occurs.
4. Nutrient absorption predominantly takes place during this phase as digested food is broken down into smaller molecules that can be absorbed through the intestinal walls.
5. The intestinal phase is also involved in preventing over-secretion of gastric juices by signaling feedback mechanisms to the stomach.

Review Questions

• How does the intestinal phase contribute to the regulation of digestive processes in the body?
  • The intestinal phase is essential for regulating digestion as it coordinates hormonal and neural signals that promote effective nutrient breakdown and absorption. When chyme enters the small intestine, hormones such as cholecystokinin (CCK) and secretin are released in response to specific nutrients. This leads to increased bile secretion from the liver and pancreatic enzyme release, enhancing digestive efficiency while also slowing gastric emptying to ensure thorough digestion.
• Discuss the role of hormones released during the intestinal phase and their impact on digestive function.
  • During the intestinal phase, hormones like cholecystokinin (CCK) and secretin play a crucial role in coordinating digestive functions. CCK stimulates gallbladder contraction to release bile, which emulsifies fats, while also promoting pancreatic enzyme secretion for protein and carbohydrate digestion. Secretin enhances bicarbonate release from the pancreas to neutralize stomach acid, creating an optimal environment for enzymatic activity in the small intestine. Together, these hormonal responses ensure efficient nutrient absorption.
• Evaluate how feedback mechanisms during the intestinal phase prevent over-secretion of gastric juices and ensure effective digestion.
  • Feedback mechanisms during the intestinal phase are critical for maintaining balance in digestive secretions. When chyme enters the small intestine, receptors sense its composition and trigger reflexes that inhibit gastric motility and secretion through pathways like the enterogastric reflex. This prevents excessive gastric juices from entering the intestines too quickly, allowing for thorough mixing with digestive enzymes. As a result, this coordination helps optimize nutrient absorption while avoiding potential damage from high acidity.

Related terms

Chyme: A semi-fluid mass of partially digested food that moves from the stomach into the small intestine during digestion.

Enterogastric Reflex: A neural reflex that inhibits gastric motility and secretion when chyme enters the small intestine, allowing for better digestion and absorption.

Hormones: Chemical messengers released by glands that regulate various physiological processes, including digestion, by affecting target organs and tissues.