This question is relevant to ask when starting a blog about breathing… On the surface, it’s a simple question but it leads to exploring physiology, psychology, bio-mechanics, and even spirituality or Faith…
Answering this question will therefore give us an idea of the potential of this physiological process which seems very simple but has considerable implications. That’s what we are going to see here.
Breathing is a movement that aims to bring oxygen to the body
The production of energy in the form of ATP (Adenosine Triphosphate) is what allows life. Indeed, this small molecule allows for a lot of chemical reactions to be carried out in a very, very short time. ATP allows us to move, digest molecules or synthesize new ones. However, the use of oxygen is more profitable than photosynthesis in terms of ATP production, the nerve of the energy war.
Unicellular organisms (yeasts, amoebas, bacteria…) can use this oxygen passively by diffusion of the molecule through their cell membrane. They therefore do not need a particular ventilation system for respiration to take place.
On the other hand, complex organisms possessing tissues had to develop a whole system to transport oxygen to different parts of the organism, to each cell. To supply organisms with O2, a ventilation system appeared: respiration. Respiration is initially nothing more than a bodily movement allowing air to penetrate the organism so that all cells can extract the oxygen. However, to make this respiration more efficient and allow the arrival of even more complex organisms, oxygen transport systems had to be developed. This is the case of the circulatory system and blood in animals and especially in humans.
Some important anatomical and physiological concepts
Respiration therefore allows a gas exchange between the external environment (the atmosphere) and an internal environment, the body. During this exchange, the oxygen contained in the air will be provided to all human tissues thanks to hemoglobin, which makes up red blood cells. In muscular tissues, it is myoglobin that will ensure this transport. Hemoglobin is a protein made up of a molecule called heme. This molecule has a very strong affinity for oxygen. Thus, when hemoglobin comes into contact with oxygen, this oxygen will easily attach to this heme molecule. Thus, the red blood cell will be able to transport this oxygen via the blood to different tissues.
This exchange of oxygen contained in the air between the external and internal environment is done by the lungs. Indeed, the lungs, composed of about 300 million tiny alveoli, provide an exchange surface of about 100 m² (half a tennis court…) to absorb oxygen (when they are not clogged by various substances!).
The transport of oxygen from the air to the tissues
Thanks to several anatomical structures. The nose first, through which air enters the body. It filters large particles, humidifies the air and begins to warm the air before it reaches the lungs. It also has an antimicrobial function thanks to the production of nitric oxide. The mouth is another possible entrance but less efficient than the nose in terms of filtration and warming. Then comes the oropharynx, a non-bony structure that can collapse (fall in on itself). Striated muscles prevent this and keep it open. When muscle tone decreases, during sleep for example, these muscles may not work as well, thus creating sleep apnea. Nasal breathing can prevent this by toning the involved muscles.
The next structure is the larynx, which has both a phonatory function as it protects the vocal cords, and a directive function as it manages the air-food crossroads. Indeed, this is where air and food are directed into their respective ducts. A dysfunction of the larynx can lead to false routes causing choking. The trachea is the structure that comes next. It extends from the larynx and descends to the bronchi. It can also trap finer particles thanks to its cilia. The mucus, climbing up, will collect them to eject them from the respiratory or digestive tracts.
Under the trachea, a first division appears, the large bronchi that enter the lungs. These bronchi divide by 2, 24 times in a row (count that… it’s a lot!) and at the end are the alveoli, where gas exchanges will take place. This is also where the pulmonary artery will be positioned, which by bringing blood not loaded with oxygen (and of rather blue color) will see the oxygen from the air contained in the alveoli diffuse inside by osmotic phenomenon. Thus, the oxygen in the blood will be captured by the hemoglobin giving a very red color, which will bring it to the different tissues via the arterial system.
CO2 evacuation
Another function of respiration is the evacuation of carbon dioxide. Carbon dioxide is a metabolic co-product resulting from catabolism. This molecule is also able to bind to hemoglobin which will bring it up via the venous system to the lungs to be exhaled.
However, although this is less known, the regulation of CO2 level in the blood is also one of the roles of respiration. Indeed, too little CO2 and oxygen can no longer be detached from hemoglobin and the blood pH becomes acidic.
Too much CO2, the blood becomes too basic, metabolism becomes anaerobic, and the nervous system panics.
Respiratory movement
The respiratory movement is amplified after exercise
The main muscle of breathing is the diaphragm. During inhalation, it descends and flattens. In response, the volume of the chest cavity expands which increases the diameter of all respiratory ducts. As it continues to descend, the chest expands and therefore the pressure in the alveoli decreases, causing a massive intake of air. At exhalation, the diaphragm relaxes, the chest cavity collapses, pressure rises again, and so air is expelled.
At rest, we breathe between 12 and 15 times per minute. This ventilation allows for about 6 to 8 liters of air per minute to be mixed. Per day, we will therefore have inhaled more than 10,000 liters of air! (or about 2000 L of oxygen). This volume can increase by at least five times during physical effort. Note, we never renew 100% of the air volume contained in the lungs. There is always a residual volume that helps keep the alveoli open, making their use less energy-consuming.
The diaphragm is a quite particular muscle since it is in direct contact with numerous bone, muscle, visceral structures, and fascias. Therefore, each of its movements affects all these structures. A contracted diaphragm can thus create dysfunctions or bone and muscle pains.
In addition to the diaphragm, a large number of so-called accessory muscles participate in the respiratory movement. We will not cover them in this article, but they also multiply the structures affected by the respiratory movement. This is why breathing is going to have an influence on body posture.
The continuous movement of the diaphragm means that the body is in fact never really at rest during our entire life. The rhythm of this movement and its intensity will have a profound impact. This impact will occur both in terms of movement, our overall relaxation, as well as the maintenance of our posture. It will also greatly affect our state of arousal.
The control and management of this respiratory movement is therefore one of the keys to access our physiology, mechanics, and psyche.
Regulation of breathing
Breathing has a particularity. It is controlled both by our will and by our vegetative nervous system. It therefore has an autonomous function that makes us breathe without thinking about it and a voluntary function linked to our control of respiratory muscles. Thus, we breathe while we sleep but we can decide the respiratory rate we use if we decide to start running.
This particularity is important. Indeed, for breathing to be under the control of an involuntary system, it means there are information sensors that inform our autonomous system of what is happening. However, if we voluntarily decide to change our breathing, these sensors will give information that we have chosen to the autonomous system. As the autonomous system influences numerous biological processes, through breathing, we can thus play with these different systems otherwise out of our control.
We can also play on our stress state and our emotional state in the same way…
Breathing regulation is therefore a key to regulating the entire functioning of the body and psyche.
Conclusion
Breathing is a physiological process that appeared with the complexification of life. Indeed, using oxygen being the most energetically profitable process, a system had to be developed to bring this oxygen to all the cells of an organism.
The arrival of this physiological process with a global impact has also influenced all body regulations. Thus, breathing will act mechanically on posture through the diaphragm, for example. It will play on our psyche by regulating the oxygen/carbon dioxide balance. It will influence blood pH which in turn influences the limbic system as we will see later. Breathing even affects the immune system!
All this makes breathing a central process, the use of which will have an effect on our entire life.
I hope you enjoyed this article and that it has laid the groundwork for better understanding the subject of this blog. You will see later how far we can go in the study of this process that seems so simple. Feel free to share this article if you want to spread the benefits of breathing around you!
See you soon
Yvan