What is the process by which food substances are broken down into simpler forms that can be absorbed by the body?

The process by which food substances are broken down into simpler forms that can be absorbed by the body is known as digestion. Digestion involves both mechanical and chemical processes. Mechanical digestion includes the physical breakdown of food, such as chewing and the action of the stomach, while chemical digestion involves the enzymatic breakdown of complex molecules into simpler ones, like proteins into amino acids and carbohydrates into sugars. These simpler forms are then able to pass through the walls of the intestines and enter the bloodstream, where they can be transported to cells throughout the body for energy and nourishment.

In contrast, absorption is the next step that occurs after digestion, where the nutrients from the digested food are taken up into the bloodstream. Metabolism refers to the chemical processes that occur within a living organism to maintain life, including the conversion of food into energy, but it encompasses a broader range of processes than just digestion. Respiration is the process of taking in oxygen and expelling carbon dioxide, which is related to energy production but distinct from the breakdown of food substances. Understanding digestion's role is crucial for recognizing how the body utilizes nutrients from food.