Structure of the respiratory system

Lungs are the primary organs involved in breathing. The right and left lungs differ from each other mainly since the left lung area also accommodates the heart, due to which the left lung is smaller (two lobes and one fissure) than the right (three lobes and two fissures).

Several muscles take part in the respiratory processes, including the diaphragm, intercostal muscles, and pectoralis minor muscles.

Illustration of a human head and torso where the organs involved in respiration are drawn and labeled. The trachea connects with the lungs, which are covered by the intercostal muscles and the ribs. The lungs are surrounded by the visceral pleura and the parietal pleura, which form the pleural cavity. The diaphragm is located below the lungs.

Figure 1. Overview of the muscles and organs that play a crucial role in respiration.

Passage of air:

  • During inspiration, the air travels into our nasal cavity, where the mucus membrane binds all pollutants and harmful agents to protect the lungs.

  • Then, the air passes through the pharynx, towards the larynx, which contains a valve that opens during breathing but closes when food is swallowed to prevent it from moving into the airways.

  • The larynx is also the section connecting the airways to the trachea, where the bronchi branch out into the left and right bronchi.

  • Bronchi subdivide into smaller branches ending with bronchioles consisting of alveoli where the gas exchange occurs.

  • Alveoli are the place where blood is being oxygenated, and waste products (such as CO2) are being disposed of.

  • Lungs are covered with a double layer of pleura which enfolds itself to form a protective barrier. The inner part, also known as the visceral pleura and outer layer, referred to as parietal pleura, are separated by a space called the intrapleural cavity. This fluid is crucial for the functioning of the lungs because it prevents the lungs from excessive friction during breathing.