How does the Respiratory System Work?

The respiratory system is an essential system of the body. It performs the task of gas exchange, allowing oxygen from the air to enter into the blood and releasing carbon dioxide from the blood to exit into the air. In fact, this is the system in your body where the inhalation of oxygen and the exhalation of carbon dioxide are done. In other words, the respiratory system can be described as a series of air passages or tubes of various sizes that help conduct air into the lung tissues.

The major organs and structures of this system includes the nose and its adjacent structures, pharynx, larynx, trachea, bronchial tree, alveoli and lungs. These organs function primarily to serve cellular respiration, maintain acid-base balance and release the waste products.

Wiki image of the respiratory system
Source: LadyofHats, Public domain, via Wikimedia Commons

How the Respiratory System Works?


The primary job of the respiratory system is to provide the body with oxygen and eliminate carbon dioxide. This process of respiration is done through breathing. When we breathe in, the air or oxygen enters our respiratory system via the nose or mouth. The air then travels down to pass through the pharynx (back of the throat) and larynx or voice box (an organ in our neck involved in voice or sound production). As the entrance of the respiratory system is uncovered, the primary task of filtering the contaminated air is done in the nose and pharynx.

The cilia, small hair-like structures, and the mucous membrane of the air passages help prevent dryness of the tissues, trap harmful substances, and filter particles and microorganisms that may enter the system. This filtered air when travels down through the larynx make a way into the windpipe or trachea (a membranous tube with cartilaginous rings that enters the chest cavity). The mucus and cilia present in the inner surface of trachea then filters any further substances and microbes, which may not have been trapped in the pharynx or nose.

The air then passes through the left and right bronchi (smaller tubes that branches off from the trachea) and enters into the lungs. As the two bronchi divides into more smaller tubes known as bronchioles and terminates in tiny balloon-like air sacs called the alveoli, the oxygen carrying air lastly travels through the bronchioles and finally passes into the alveoli. These alveoli then absorb oxygen and diffuse it into the arterial blood through the capillaries (tiny blood vessels surrounding the alveoli).

This oxygenated blood then enters into the cardiovascular system, leaving the lungs, and travels to the heart so that the heart can pump it throughout the body to provide the required oxygen. In the meantime, the carbon dioxide travels back to the lungs via the capillaries and diffuses into the alveoli for the exhalation. Finally, following the same path of inhalation, our body exhales out carbon dioxide just immediately after the inhalation.

The diaphragm, a thin but large dome-shaped muscle found below the lungs, also plays an important role during the respiration. It aids in pulling the oxygen into the lungs and pumping out the carbon dioxide from the body.

The respiratory system is closely linked with the cardiovascular system for the elimination of carbon dioxide and supply of fresh oxygen to the heart. To learn more about how cardiovascular system is connected with the respiratory system, read How does the Human Body Cardiovascular System Work?

Follow the below chart, to simply remember how the process of respiration is done in the body.

Flow chart of inhalation process

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