Its chyme.
chyme
The original answer posted was Cholecystokinin, which is actually a peptide hormone that is released to inhibit gastric mobility. But it is not the first hormone to be released when fat or food initially contacts the duodenum.When Fat enters the duodenum, this accounts for the third phase of gastric secretion, called intestinal phase. This phase accounts for 5% of the total secretory response. It begins when food leaves the stomach and enters the small intestine (duodenum). When the food first contacts the intestinal wall, it stimulates intestinal cells to release a hormone called, intestinal gastrin, that enhances gastric gland secretion.
Once the food is chewed and is swallowed it is referred to as a bolus. Once it enters the stomach and is churned and exposed to the gastric secretions it enters the duodenum becoming chyme.
No. Because bile, together with pancreatic fluid is secreted into the the first part of the small intestine, the duodenum. And bile secretions cannot pass through the pyloric sphincter, normally.
duodenum
duodenum
There is a site on the duodenum called Ampulla of vater where the common bile duct joins with the pancreatic duct and enters into the small intestine at the duodenum.
In humans the pH of bile as it enters the duodenum is around 7.6
it first passes through the duodenum
secretin
cystic duct
As chyme moves through the duodenum, it becomes less acidic and more alkaline. This is because the pancreas secretes bicarbonate ions into the duodenum, which helps neutralize the acidic chyme coming from the stomach. Additionally, the liver also contributes bile salts to the duodenum, which further helps to alkalize the chyme.