What are the primary functions of the digestive system?

The primary functions of the digestive system center around the processes of breaking down food, absorbing nutrients, and eliminating waste. When food enters the digestive tract, it undergoes mechanical and chemical breakdown through processes such as chewing, enzymatic action, and various digestive secretions. This breakdown is essential for converting complex food substances into simpler molecules that can be absorbed.

Once the food is adequately digested, the nutrients released into the bloodstream are vital for various bodily functions, including energy production, cellular repair, and growth. The absorption primarily occurs in the small intestine, where the walls are lined with villi and microvilli that increase the surface area, facilitating maximum nutrient uptake.

Finally, the elimination of waste is an essential function of the digestive system as it ensures that indigestible substances and by-products of digestion are expelled from the body, maintaining overall health.

In contrast to the other options, which refer to unrelated physiological systems or functions—such as circulation, respiration, and hormone production—this choice succinctly captures the core responsibilities of the digestive system.