What's the breath got to do with it? Part 2: the anatomy of a breath

If you haven't already, you can read part 1 here.

This article is for information purposes and not to be considered medical advice. Please connect with your healthcare provider to address your own personal needs.

A single breath: inhale, exhale. That's it. Easy. Automatic. Happens about 20,000 times a day from the time we are born till our final moments in this life.

I invite you to take a moment and tune into your breath. Notice and feel the inhale. Where is the air entering your body? What parts of your body expand? Is it easy? Is it forced? Now notice and feel the exhale. How does the air leave your body? What parts of your body soften? Is it easy? Is it forced?

So, what is it that's happening when we breathe? Many of us are aware of the basics of breathing, air comes in - the body gets oxygen, air goes out - the body releases carbon dioxide. You might think (I did until I learned more) that the brain/body triggers an inhale when more oxygen is needed, but it's actually the other way around! We inhale when there's too much carbon dioxide in the body. Carbon dioxide (which is often just referenced as a waste gas) serves as the signal triggering a breath in and your body's tolerance for carbon dioxide impacts how much/how fast you breath.

Want to get a sense of your body's carbon dioxide tolerance? This can give us an indication of how adaptable our bodies are and how we handle stress. Here's a simple test you can do:

1. Take three slow easy breaths

2. Fouth breath, fill your lungs completely, start a timer and release the exhale as slowly as you can

3. Stop the timer when you run out of air

Results:

< 20 seconds means your Co2 tolerance needs some work

20-40 seconds is the average time that most people achieve

40-60 seconds is an above-average score that represents good CO2 tolerance

> 60 seconds means a healthy pulmonary system and good stress + breath control

(https://www.hanuhealth.com/learn/co2-tolerance-explained-how-to-train-and-test-it/)

There are two ways that air can enter our bodies - the nose and the mouth. Both are functional but the nose is more catered to this. The nasal passage is first lined with fine hairs that help to filter out dust and other particles, preventing them from entering the body, and it is also equipped with the ability to create nitric oxide which sanitizes the air, removing bacteria and viruses. This combination helps prevent us from inhaling anything that has the potential to harm us or make us ill. Breathing through the nose also helps to warm and hydrate the air to match the state of the rest of the system.

Once the air has entered our system it moves down through the throat (pharynx), through a solid tube called the trachea. This needs to be solid and firm so that it doesn't collapse as we pull air in, especially when we do it forcefully. Think about sucking through a plastic straw, if you use too much force it flattens and nothing gets through - obviously not ideal if that was the case within our bodies - versus a metal straw that can't collapse on itself. From here the air moves into the bronchi which splits to enter both the right and left lung. These then continue to split throughout the lungs into what are called bronchioles which connect with the alveoli (air sacs) where gas exchange occurs with the blood vessels.

(https://www.urmc.rochester.edu/encyclopedia/content.aspx?contentid=p01300&contenttypeid=85)

This whole system is powered by the diaphragm (a large muscle located under the lungs) and intercostal muscles (the ones between the ribs that allow the rib cage to expand with an inhale). These muscles contract, the diaphragm moves down pushing the belly out and the intercostal muscles expand the ribs out, which creates more space in the lungs and lowers the air pressure in the body which is what allows air to move from outside of us to inside, creating an inhale. These muscles then relax, the diaphragm moves up and the ribs come in, which increases the air pressure in the body pushing air out, creating an exhale.

The guide that keeps the system running is the phrenic nerve. This nerve runs from the cervical spine (C3, C4, and C5) in the neck down to the diaphragm, signaling it to contract and relax creating our inhale and exhale. Sensors in the muscles provide information on how active one is at any given time and sensors in the brain and blood vessels monitor the levels of oxygen and carbon dioxide. The brain uses this information and communicates to the phrenic nerve to ensure the body breathes in the best way possible for current circumstances.

Generally, we don't have to think about breathing (thankfully, it would be very challenging to do anything else if we did!) as it is all controlled by the autonomic (also called involuntary) nervous system. Our brain and body just do it for us so we can continue on with this life and all it has to offer.

Did you know?

Hiccups are a result of phrenic nerve irritation causing the diaphragm to spasm. There are so many tips and tricks out there for getting rid of hiccups - the effectiveness of which is definitely up for debate.

A trick that Dr. Andrew Huberman talks about in his podcast, Huberman Lab, and says will work every time is to inhale three times in a row (the second and third inhales may be tiny sips of air) to max out your lung capacity, hold the breath for about 20 seconds, and slowly release the exhale. This is intended to calm and basically reset the nerve.

I haven't had an opportunity to test this since I heard about it. Would love to hear in the comments if you try it whether or not it works for you.

In part 3 of this series we'll take a look at ways we can work with the breath to bring our energy up, calm ourselves down, and find balance. Until then, happy breathing!