Breathing in and out is a function that we are mostly unaware of in our everyday lives. Breath is part of our autonomic nervous system (ANS), which performs almost all of our bodily functions automatically. The ANS is also called the involuntary nervous system because it functions without conscious, voluntary control. It controls the heart muscle, smooth muscle, and various endocrine and exocrine glands, as well as the activity of most tissues and organ systems in the body (McCorry, 2007).
The various functions in our body are also associated with the parasympathetic and sympathetic nervous systems. When we feel calm, our breathing is naturally slow. On the other hand, when we are stressed, it is shallower and faster. This happens involuntarily. But here is where breath work comes in. The breath is the only function of the autonomic nervous system that we can control voluntarily. We can change the pace and the depth, and the cavity into which we breathe. Let’s take a closer look at the anatomy behind this and how we can work with each part or with all of them together.
Our breath consists of two processes. Inhalation, in which the air flows into the lungs, and exhalation, in which the air leaves the lungs. In the medical world, this is called pulmonary ventilation. Breathing is a component of what is called the respiratory system, a network of organs and tissues that support breathing.
This includes airways, blood vessels and the lungs. The muscles, including the diaphragm, that perform the movement are also part of the respiratory system, located in the chest cavity or thoracic cavity. All of these parts work together to deliver oxygen to the body and expel waste gases such as carbon dioxide. The entire respiratory system is controlled by the respiratory center in the brain stem.
As a child, I used to imagine that when I breathed in, I sucked in the air with the force of my nose. And when I exhale, I push it out of my nostrils. The same for mouth breathing. Fortunately, I was enlightened by some anatomy models.
The lungs can be modelled as a large vessel. On top is a tube with two ends shaped like an upside down Y. A balloon is attached to each end to represent the two lungs. The large jar is closed underneath with a rubber lid, which is the diaphragm. When the rubber lid is pulled down, the two balloons are filled with air. It is not a small nasal fan that does this, but rather an atmospheric process.
As you inhale, the diaphragm contracts and pulls it down toward the abdominal cavity. This creates a negative pressure in the expanded lungs, and air rushes in, because the of higher pressure in the air outside of the body. When the diaphragm relaxes on exhalation, the pressure in the thoracic cavity increases and air flows out.
But it is not as simple as the model, it is much more complex. First, our diaphragm is not the only muscle that does the work. There are many other muscles between the ribs, at the back of the rib cage and next to the neck. Also, our rib cage is not static like the model. It expands in different directions when we breathe in, changing the volume of the lungs. Also, the diaphragm is not a disk. It looks more like a parachute or dome that is connected to the rib cage and spreads it apart when we inhale.
As we have learned, the respiratory system consists of two cavities, the thoracic and abdominal cavities. The thoracic cavity can change its volume and is the active part of respiration. The abdominal cavity can be thought of as a balloon filled with water. It can change its shape, but not its volume. When we breathe in, the diaphragm pushes the abdominal cavity down and it expands forward.
If you put your hand on your belly, you can feel it expand when you inhale. You have probably heard many times: “Breathe into your belly. This does not mean that the air actually flows into the abdomen, as seen in the model. It just means that the diaphragm is more active than in chest breathing. Both abdominal and chest breathing have their advantages.
In chest breathing, the diaphragm is also involved, it’s just not as active. Instead, the muscles around the chest are more activated to expand it in multiple directions. We can practice this by pulling the belly button toward the spine and focusing on expanding all areas of the chest cavity. The idea of drawing the breath under the shoulder blades and toward the collarbones can help.
Chest breathing is usually short and quick, as opposed to long and deep abdominal breathing. It is shallower and does not fully engage the lungs. Especially during exhalation, an imbalance of oxygen and carbon dioxide can occur. Which is intentional in certain breathwork techniques such as Tummo/Wim Hof breathing. Hyperventilation increases the amount of oxygen in the blood and causes more carbon dioxide (CO2) to be exhaled.
Sometimes chest breathing can be good in practice for special purposes. In general, abdominal breathing is preferable from a health perspective. Abdominal or chest breathing allows the diaphragm to use its power to empty the lungs. More oxygen is released into the bloodstream due to the greater intake of air and the greater amount of carbon dioxide released. The slower and deeper breathing of abdominal breathing has a calming and relaxing effect. This breathing allows you to use your lungs at 100% capacity to increase lung efficiency.
In daily life, when we let the autonomic nervous system do its work, we do not breathe with 100% lung capacity. It is a mixture of chest and abdominal breathing. Depending on activity or physical condition, breathing varies. It is either more chest-heavy or belly-heavy. Nowadays due to many factors a lot of people breathe through their mouth which indicates shallow chest breathing causing various health issues such as chronic stress, asthma and chronic allergies.
Through breath work, we can shift the breathing in our daily life towards deep abdominal breathing and strengthen the diaphragm. It is more important than ever to know how the anatomy of breathing works and how to restore breathing to a healthy state.
References:
Guyton and Hall: Textbook of Medical Physiology, 13th edition, Elsevier
Written by
Zoe Levit
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Copyright © 2022 | Breathless
Copyright © 2022 | Breathless
