Final answer:
Bile is a fluid produced by the liver and secreted into the duodenum to aid in digestion of lipids and neutralize stomach acid.
Step-by-step explanation:
The liver is an organ of both digestion and excretion. It produces a fluid called bile, which is secreted into the duodenum. Some bile also goes to the gallbladder, a sac-like organ that stores and concentrates bile and then secretes it into the small intestine.
In the duodenum, bile breaks up large globules of lipids into smaller globules that are easier for enzymes to break down. Bile also reduces the acidity of food entering from the highly acidic stomach. This is important because digestive enzymes that work in the duodenum need a neutral environment.
The pancreas contributes to the neutral environment by secreting bicarbonate, a basic substance that neutralizes acid.