Understanding the Respiratory System: Anatomy and Function

The Respiratory System

The respiratory system is responsible for ensuring the supply of oxygen to body cells and removing carbon dioxide. Blood oxygenation is a process that occurs through gas exchange between the blood vessels and the pulmonary alveoli. The respiratory system also prevents the entry of unwanted elements and the development of infections.

Anatomy of the Respiratory System

The respiratory system consists of various organs, which are divided into:

Upper Airways

Located outside the thoracic cavity, including the nose, nares, pharynx, and larynx.

Lower Airways

Located inside the chest cavity, including the trachea, bronchi, bronchioles, alveoli, lungs, and pleura.

Upper Respiratory Tract

1. Nose

   The air enters through the nostrils, right and left, which are separated by a cartilage and bone septum called the nasal septum. There are three bony turbinates, which increase the surface area. The functions of the nose are:

   • The nasal mucosal nerve endings are responsible for the sense of smell.
   • The surface of these cavities is wet with mucus and warmed blood, so that the air passing through the nose warms.

   Nasal sinuses, four in total, are lined with mucus-secreting epithelium that drain into the nasal cavity through holes located in the turbinates. When inflamed, they produce a condition of hypertension and local pain called sinusitis.

2. Choanae

   Connects with the pharynx, allowing communication between the nostrils and the upper part of the pharynx.

3. Pharynx

   The common passage for the digestive and respiratory systems. It is divided into three parts: the nasopharynx (located behind the choanae), the oropharynx (behind the mouth), and the laryngopharynx (the inner segment, which connects with the larynx).

4. Larynx

   The organ of phonation, consisting of several cartilages, such as the epiglottis, cricoid, thyroid, and arytenoid.

5. Trachea

   A tube that extends from the larynx to its division into the main bronchi.

6. Bronchi, Bronchioles, and Alveoli

   The trachea splits into two tubes called bronchi, which penetrate each lung. Within each lung, the bronchi branch into smaller tubes called respiratory bronchioles and alveolar sacs.

7. Lungs

   Located inside the space that houses the heart, trachea, esophagus, and part of the aorta and vena cava. They are bound to the thoracic walls by the pleura, a tissue divided into left and right.

8. Pleura

   A double-layer membrane that surrounds the lung on one side and lies on the chest wall on the other. It aids in lung inspiratory movements, expanding it and allowing air to enter. Disturbance of the pleura causes air to enter and the collapse of the lungs.

Respiratory Physiology

Breathing is an autonomous process regulated by the brain based on the concentrations of O2, CO2, and H+ ions in the plasma.

Breathing

Includes two movements into and out of the lungs:

1. Inspiration

   The process by which air is inhaled, allowing environmental and respiratory gases to penetrate the alveoli. It is produced by the contraction of the diaphragm.

2. Expiration

   The process that reduces the size of the lungs as the respiratory muscles relax after inspiration. It disposes of the gases that are exchanged in the alveoli.

Physiology of Gas Exchange

1. Gas Exchange

   Occurs in the alveoli through the alveoli-capillary membrane. It is a passive process and is regulated according to the partial pressures of gases.

2. Transportation of Gas

   Gas exchange circulates in the blood bound to hemoglobin and dissolved in serum in small amounts.