Final answer:
Secretin stimulates the pancreas to secrete a solution high in bicarbonate to neutralize acidic chyme. Option D is correct.
Step-by-step explanation:
The hormone secretin plays a crucial role in the digestive process by triggering the pancreas to release a bicarbonate-rich solution. Specifically, this hormonal response occurs in the duodenum, the initial segment of the small intestine. The release of secretin is prompted by the arrival of acidic chyme into the duodenum from the stomach.
Upon detecting the acidic nature of the chyme, secretin acts as a signaling molecule, prompting the pancreas to produce and release an alkaline solution with a high concentration of bicarbonate ions. This bicarbonate-rich secretion serves a vital purpose in the digestive cascade. Its primary function is to counterbalance the acidity introduced by the chyme from the stomach. By neutralizing the acidic content, the bicarbonate solution creates a more conducive environment for the subsequent digestive enzymes to function optimally.
In essence, the secretion of secretin orchestrates a finely tuned physiological response that ensures the maintenance of an appropriate pH level in the duodenum. This regulatory mechanism not only highlights the intricate coordination within the digestive system but also emphasizes the significance of hormonal signaling in orchestrating the physiological processes essential for effective digestion and nutrient absorption.