What is digestion primarily concerned with?

Digestion is primarily concerned with breaking down food and absorbing nutrients. This process begins in the mouth, where food is mechanically broken down by chewing and chemically broken down by enzymes in saliva. It continues in the stomach and small intestine, where enzymes and stomach acids further digest food into smaller molecules.

Once the food is broken down into basic nutrients, such as amino acids, fatty acids, and simple sugars, these nutrients are absorbed through the walls of the intestines into the bloodstream. This absorption is crucial because it allows the body to utilize these nutrients for energy, growth, and repair, which are fundamental processes for maintaining health and supporting cellular functions.

In contrast, building cellular structures, regulating blood sugar levels, and transporting oxygen are different physiological processes that rely on the outcomes of digestion but are not the primary function of the digestive system itself. Building cellular structures pertains more to metabolic processes, while blood sugar regulation involves the endocrine system, and oxygen transport is a function of the respiratory and circulatory systems.