The human respiratory system is responsible for supplying oxygen to the body’s cells and removing carbon dioxide. It consists of several organs including the nose, pharynx, larynx, trachea, bronchi, and lungs.
Did you know that the right lung is slightly larger than the left lung? This is because the left lung has to accommodate the heart, which is tilted to the left. On the other hand, the right lung is shorter and wider to make space for the liver, which is located below it. Due to its larger size, the right lung supplies more oxygen to the body compared to the left lung!
Another interesting fact is that we only breathe through one nostril at a time. This phenomenon is known as the nasal cycle, although the exact reason behind it is still not fully understood!
These facts provide some basic information about the organs involved in supplying oxygen to the body. The respiratory system includes the nose, lungs, pharynx, larynx, trachea, and bronchi.
So, how does the respiratory system actually work?
Functions Of The Respiratory System
The main function of the respiratory system is to supply oxygen to the body. It would be inefficient for each cell to individually obtain oxygen. Therefore, the respiratory system takes in oxygen from the atmosphere and transfers it to the circulatory system, which then transports oxygen throughout the body.
In addition to taking in oxygen, the respiratory system also eliminates carbon dioxide (CO2). Cells produce CO2 as a byproduct of metabolism, and this excess CO2 needs to be expelled. The respiratory system facilitates the exchange of fresh oxygen for old CO2, a process known as gas exchange!
By expelling CO2, the respiratory system helps maintain the blood pH at an optimal level of 7.4.
Moreover, the respiratory system enables us to speak and smell.
Organs Of The Respiratory System
These vital functions are carried out by various organs within the respiratory system, including the nose, pharynx, larynx, trachea, bronchi, and lungs.
When air enters the body, it first passes through the nose. The epithelial cells in the nose produce mucus, which moisturizes the air, while blood vessels bring in heat to warm the air. The mucus also traps any dirt or pathogens that may try to enter the lungs.
The nose also contains millions of olfactory receptors that enable us to smell our surroundings.
Organs of the lungs (Photo Credit: OpenStax College / Wikimedia Commons)
From the nose, air travels through the pharynx and larynx before entering the trachea. The pharynx and larynx connect the nasal cavity to the trachea and help keep our air passages open during breathing. The larynx houses the vocal cords, which allow us to produce sound as air passes over them.
The trachea, supported by C-shaped cartilage rings and smooth muscles, is a long tube. Its inner lining is coated with mucus to prevent foreign particles from entering and to keep the air moist.
Think of the trachea as a long pathway. As you move down the trachea, it divides into the bronchi, which further divide into the bronchioles. Through the branching pathways of the bronchi, air travels into the lungs. This process continues until the bronchioles end in the alveoli of the lungs. The alveoli are where the exchange of gases takes place. They are air-filled sacs, similar to balloons, that are in contact with the capillaries. The capillaries bring oxygen-poor and carbon dioxide-rich blood to the lungs.
The process of breathing begins with the brain, specifically the medulla oblongata. When the brain senses the need for more oxygen, it sends signals to the respiratory system to inhale. The muscles and bones associated with the respiratory system then come into action. The muscles pull and push the lungs, causing them to expand and contract. Breathing relies on the principle of pressure differences. The difference between the pressures inside the lungs and the outer environment determines whether air will flow into or out of the lungs. By changing the volume of the lungs, the pressure difference is created. When we breathe in, we expand our lungs, resulting in a lower pressure inside the lungs compared to the atmosphere. As a result, air from the outside flows into the lungs.
The exchange of gases in the alveoli occurs based on the principle of partial pressures. Each gas in a mixture exerts its own pressure. In the alveoli, the partial pressure of oxygen is high, while in the blood vessel, it is low. This causes oxygen to move from the alveoli into the blood vessel. On the other hand, carbon dioxide has a high partial pressure in the blood vessel and a low partial pressure in the alveoli, causing it to flow from the blood vessel into the alveoli. This constant exchange of gases takes place in the approximately 500 million alveoli in the lungs. The oxygen-rich blood then circulates to the rest of the body to supply oxygen to the cells.
Exhalation – Exhaling
The lungs contract inward to release carbon dioxide. This action reduces the lung volume and increases pressure. As a result, the pressure inside the lungs becomes higher than the pressure in the atmosphere, causing air to move out of the lungs and into the air. By doing so, you have completed a full breathing cycle!
A Final Message
Our respiratory system plays a vital role in our immune system. The mucus and hairs in our nose and trachea prevent foreign particles from entering our bodies. The lungs also have their own defenders, macrophages, which safeguard the lungs against any invading pathogens.
Most of the time, we unconsciously perform this intricate process to ensure that our bodies receive enough oxygen. Breathing is one of the most natural actions we, as living beings, carry out—it is both the first and last thing we do!
So, the next time you take a deep breath and savor the scent of a warm sunny day outside, remember to express gratitude to your hardworking lungs for enabling all of that to happen!