Final answer:
The hilum is the concave structure in the root of the right lung where essential components such as blood vessels and bronchi enter and exit the lung.
Step-by-step explanation:
The structure in the root of the right lung is called the hilum. This is a concave region found on the mediastinal surface of the lung, which serves as the point of entry and exit for blood vessels, lymphatic vessels, nerves, and the bronchus. The right lung is larger and has three lobes, while the left lung is smaller with only two lobes to accommodate the heart. In the context of the respiratory system, the lungs' primary function is to exchange oxygen and carbon dioxide with the atmosphere, and they do so across a large surface area of the alveoli.