Which of the following is NOT part of the respiratory system?

The liver is not part of the respiratory system because its primary function is to process nutrients from the digestive system, detoxify harmful substances, and produce bile for digestion, among other metabolic processes. In contrast, the respiratory system is specifically designed for gas exchange, allowing oxygen to enter the body and carbon dioxide to be expelled.

The pharynx, bronchi, and larynx are all integral components of the respiratory system. The pharynx serves as a pathway for air to move from the nasal cavity to the larynx and esophagus. The bronchi branch off from the trachea and distribute air to the lungs. The larynx not only plays a critical role in producing sound but also acts as a passageway for air entering the lungs and contains structures that protect the airway during swallowing.