Which system is primarily responsible for digestion and nutrient absorption?

The digestive system is primarily responsible for digestion and nutrient absorption. This system includes various organs such as the stomach, intestines, liver, and pancreas, which all work together to break down food into smaller components that the body can utilize. The process begins in the mouth, where food is mechanically and chemically processed, and continues throughout the gastrointestinal tract, where nutrients are absorbed into the bloodstream.

During digestion, food is broken down into macronutrients—carbohydrates, proteins, and fats—as well as vitamins and minerals. Once digested, these nutrients are absorbed primarily in the small intestine, which has a specialized structure that enhances absorption efficiency. The nutrients provide energy and are essential for growth, repair, and maintenance of the body.

In contrast, other systems mentioned, such as the excretory system, are involved in the elimination of waste products, while the respiratory system is responsible for gas exchange, supplying oxygen to the body and removing carbon dioxide. The nervous system regulates bodily functions and responses but does not directly participate in the digestion process. Thus, the digestive system is the correct choice as it directly handles the processes of digestion and nutrient absorption.