Answer :
Final answer:
Pancreatic juice is alkaline due to the presence of sodium bicarbonate, which helps to buffer and neutralize the acidity of chyme, creating an optimal environment for the activity of digestive enzymes.
Explanation:
Pancreatic juice is alkaline due to the presence of sodium bicarbonate, which causes the pH of pancreatic juice to range between 7.1 and 8.2. This slight alkalinity serves several important functions: it helps to buffer the acidic gastric juice contained within chyme, neutralize the acidity to provide an optimal environment for the activity of digestive enzymes in the small intestine, and inactivate pepsin from the stomach.
The pancreas secretes over a liter of this enzyme- and bicarbonate-rich pancreatic juice daily, which is crucial for the digestion of sugars, proteins, and fats. Hormones and the parasympathetic nervous system regulate pancreatic secretion – the arrival of acidic chyme in the duodenum stimulates the release of secretin, causing the duct cells to release more bicarbonate into the pancreatic juice, while the presence of proteins and fats triggers the release of CCK, further enhancing digestive enzyme activity.