Understanding the Human Respiratory System: Anatomy and Function
Understanding the Human Respiratory System
The respiratory system is a set of organs responsible for the entry and exit of air into our body. Air enters through the nostrils, which connect to the nasal passages. Air can also enter through the mouth, passing through the pharynx and into the esophagus. The first section of the esophagus is the larynx, formed by a series of cartilages. Next, air enters a rigid tube called the trachea, which eventually divides into two branches called bronchi. Each bronchus leads to a lung. Within each lung, the bronchi branch into numerous, ever-smaller tubes called bronchioles, which terminate in small sacs called alveoli.
The larynx is located at the entrance of the trachea and contains a cartilage called the epiglottis. The epiglottis covers the entrance to the trachea during swallowing to prevent food from entering and causing choking. Furthermore, the larynx contains vocal folds, also known as vocal cords, which are responsible for the emission of sounds. During breathing, the glottis is open to allow air to pass through. However, when we speak, the glottis partially closes, and the vocal cords vibrate as air passes through, producing sound. The larynx and mouth act as resonators, creating different sounds. Other structures, such as the teeth, tongue, and lips, contribute to the articulation of consonants, forming words composed of vowels and consonants, the significance of which we learn from childhood.
Cellular respiration is a chemical process that occurs in every cell of the body, involving the burning of nutrients to release energy. Focusing solely on the respiratory system, it consists of two lungs filled with pulmonary alveoli, supplied by the bronchial tubes that lead through the trachea and larynx into the pharyngeal cavity. We inhale air from the outside and exhale carbon dioxide (CO2) from cells throughout the body. These movements are facilitated by various anatomical structures that help inflate and deflate the lungs. Additionally, the diaphragm, a muscle located at the waist, contracts to increase the volume of the thoracic cavity, allowing air to be inhaled into the lungs, and relaxes to decrease the volume. The lungs are enclosed in the thoracic cavity, so a decrease in the volume of the cavity increases the pressure on the lungs, forcing air out, and vice versa.
During inspiration, air enters through the trachea, bronchi, and bronchioles, reaching the alveoli. The concentration of oxygen in the alveoli is greater than in the blood, so oxygen passes through the walls of the alveoli and into the blood capillaries, where it combines with a pigment called hemoglobin, found in red blood cells. Red blood cells transport the oxygen to the cells. Simultaneously, carbon dioxide (from cells throughout the body) passes from the blood into the alveoli because the concentration of carbon dioxide in the blood is higher than in the alveoli. This allows for the elimination of carbon dioxide during expiration.