Final answer:
The local response in the stomach during the gastric phase is characterized by mixing waves initiated by the myenteric plexus, chemoreceptor activation by partially digested peptides, and the stimulation of acid secretion by released histamines.
Step-by-step explanation:
During the gastric phase of gastric regulation, which begins when food reaches the stomach, the local response includes several changes to aid in digestion. These changes can be described by the statements:
- Signals from the myenteric plexus trigger forceful contractions called mixing waves, which help in the mechanical breakdown of food.
- The response is indeed triggered by chemoreceptors in the stomach that sense partially digested peptides, signaling the need for continued digestion and secretion of gastric juices.
- Released histamines stimulate parietal cells to secrete acid, assisting in creating an acidic environment necessary for digestion.
However, stressful situations do not directly inhibit the local response during the gastric phase. Instead, chronic stress can lead to reduced blood flow to the stomach and possibly lead to an increased risk of gastrointestinal issues.