Which of the following is NOT a component of the respiratory system?

The kidneys are not part of the respiratory system; they belong to the urinary system. The primary function of the kidneys is to filter blood, remove waste, and regulate fluid and electrolyte balance in the body. In contrast, the nasal cavity, trachea, and bronchi are integral components of the respiratory system, which is responsible for the exchange of gases between the body and the environment. The nasal cavity filters, warms, and humidifies air before it enters the lungs, while the trachea serves as a pathway for air to travel to and from the lungs. The bronchi further divide into smaller branches within the lungs, ensuring that air reaches all areas necessary for efficient gas exchange. Understanding the distinctions between bodily systems is important for comprehending anatomy and physiology.