To describe the role of the gallbladder in digestion, let’s start with what we eat. Human beings are omnivores; we’ll eat just about anything. We often eat meat and dairy products that contain a significant percentage of fats. These foods contain animal fats, which are complex as fats go and potentially contain a lot of useful energy. However, these fats are polyglycerides, which are forms of fat compounds with molecules so large that the body can’t use them. So, one of the jobs of digestion is to convert (emulsify) polyglycerides into much smaller monoglycerides that can be absorbed by the intestines and eventually turned into cellular energy.
After breakdown by the acids in the stomach, what’s left of your meal enters the top of the small intestine at the duodenum. Here there is a hormone, cholecystokinin (CCK), which reacts to the presence of fats – the more fat, the more it reacts. The more it reacts, the stronger the signals it sends through the nervous system to the pancreas and gallbladder ordering them to deliver digestive bile.