Final answer:
The gallbladder is a small sac below the liver that stores and concentrates bile, which is then secreted into the small intestine for fat digestion.
Step-by-step explanation:
The gallbladder is a small sac below the liver that stores some of the bile from the liver. The gallbladder also concentrates the bile by removing some of the water from it. It then secretes the concentrated bile into the small intestine as needed for fat digestion following a meal.