Final answer:
In the duodenum, the release of HCO₃⁻ (bicarbonate) is stimulated by the hormone secretin, which acts on the pancreas to produce and release alkaline bicarbonate-rich pancreatic juice. Cholecystokinin (CCK) also plays a role in the release of HCO₃⁻ by stimulating the pancreas and gallbladder.
Step-by-step explanation:
In the duodenum, the release of HCO₃⁻ (bicarbonate) is stimulated by the hormone secretin, which is produced in response to the entry of acidic chyme into the duodenum. Secretin acts on the pancreas to stimulate the production and release of alkaline bicarbonate-rich pancreatic juice, which helps to neutralize the acidic chyme.
In addition to secretin, another hormone called cholecystokinin (CCK) is also involved in the release of HCO₃⁻. CCK stimulates the pancreas to produce the necessary pancreatic juices and the gallbladder to release bile into the duodenum.