What organs are primarily involved in the digestive system?

The organs primarily involved in the digestive system include the mouth and salivary glands because they play a critical role in the initiation of the digestive process. The mouth is where food enters the body, and it is here that mechanical digestion begins through chewing, while enzymatic breakdown of carbohydrates starts with the salivary enzymes.

The salivary glands secrete saliva, which contains enzymes such as amylase that begin the digestion of starches. Additionally, saliva helps lubricate food, making it easier to swallow and aiding in the overall process of digestion. This initial phase is vital for breaking down food into smaller particles, making it easier for the subsequent organs in the digestive tract, such as the esophagus, stomach, and intestines, to further process the food.

The other options correspond to organs and systems that are not directly related to digestion; the lungs and trachea are part of the respiratory system, the nerves and brain pertain to the nervous system, and the heart and arteries are components of the circulatory system. Each of these systems serves different essential functions within the body but does not play a direct role in the digestion of food.