The Respiratory System

The respiratory system is essential for delivering oxygen to cells for energy production and removing carbon dioxide. It involves pulmonary ventilation (breathing) and external respiration (gas exchange).

The system includes the nose, nasal cavity, sinuses, and pharynx. The nose filters, heats, and moistens air, while the pharynx serves as a passageway for both air and food, separated by the epiglottis in the larynx.

The trachea divides into bronchi, which branch into smaller bronchioles. The transition from the conducting zone to the respiratory zone occurs at the respiratory bronchioles, leading to the alveoli.

Alveoli facilitate gas exchange via thin walls and pulmonary capillaries. The lungs occupy the thoracic cavity, divided into lobes, and are protected by the pleura.

Breathing is driven by pressure changes facilitated by the diaphragm and intercostal muscles. The negative pressure in the pleural cavity keeps the lungs inflated, allowing oxygen to diffuse into the blood.