What are the small tubes called that branch out from the trachea?

The small tubes that branch out from the trachea are called bronchi. When air enters the respiratory system, it travels down the trachea, which then divides into two primary bronchi that enter each lung. These bronchi further subdivide into smaller bronchi and eventually into even smaller tubes known as bronchioles. This branching structure is crucial for delivering air to the lung tissues where gas exchange takes place.

The other terms relate to different functions or structures within the respiratory and circulatory systems. Alveoli are the tiny air sacs in the lungs where oxygen and carbon dioxide exchange occurs. Capillaries are tiny blood vessels that facilitate the exchange of substances between blood and tissues, while arteries are blood vessels that carry blood away from the heart. Each of these plays an essential role in their respective systems, but they do not directly describe the small tubes branching from the trachea.