I would have to say both the minute capillaries and the mucosa.
If a person had an infection of the respiratory system, they would most likely have a cough.
lungs
the most crucial
The respiratory system is most vulnerable to sulfur mustard exposure. When sulfur mustard is inhaled, it can damage the respiratory tract, causing inflammation, blistering, and potentially leading to respiratory failure.
The respiratory system interacts most directly with the circulatory system in terms of function. Structurally, it shares some body parts with the digestive system.
Medulla Oblongata
The single most expensive component of a system built from separate components is generally the processor.
Your question is unclear. Are you asking what does the most in the respiratory system , then tiny little sacs called the alveoli do.
Because a dolphin is a mammal, and not a fish. A dolphin's respiratory system is similar, for the most part, to a human's respiratory system.
you (most likely) die
respiratory. also lymphatic.
The most common use of the respiratory system is the exchange of gases. When you exhale carbon dioxide, at the same time you inhale oxygen.