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Breathing Basics - Part 1: Anatomy and Physiology

Updated: Apr 8

Breathing ensures healthy CO2 levels. The main functions of breathing are gas exchange and acid-base (pH) regulation. The respiratory system exchanges oxygen for carbon dioxide (CO2) released by cells during metabolism. CO2 regulates our physiology by increasing nitric oxide and oxygen delivery when tissues are more active. Our body uses 85-88% of CO2 to ensure a healthy acid-base balance, making gas exchange possible through the Bohr effect (Khazan, 2021).

Without sufficient carbon dioxide, the oxygen that we have remains in the bloodstream and does not go into our tissues, where it is most needed (Khazan, 2019, p. 27).

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Dr. Khazan explains internal respiration © Association for Applied Psychophysiology and Biofeedback.


The abbreviation pH refers to the power of hydrogen, which is the concentration of hydrogen ions. Acidic solutions have a low pH (< 7) due to a high concentration of hydrogen ions. A neutral solution of distilled water has a pH of 7. Alkaline or basic solutions have a high pH (>7) due to a low concentration of hydrogen ions. The pH level regulates oxygen and nitric oxide release. Graphic © AlexVector/

pH scale

Hemoglobin molecules on red blood cells transport nitric oxide and oxygen through the bloodstream. Graphic © Designua/


Hemoglobin rarely carries all four nitric oxide and oxygen molecules simultaneously. Red blood cell graphic ©

red blood cells

When nitric oxide reaches the capillaries, it promotes dilation, increased blood flow, and improved vascular function. Increased blood flow delivers more oxygen and nutrients to the tissues and removes waste products more effectively. This is particularly important during exercise when skeletal muscles require additional oxygen and nutrients to maintain performance. After oxygen-rich blood enters the capillaries, oxygen disperses into cells to power aerobic cellular respiration (Fox & Rampolski, 2022). Capillary graphic © hareluya/

Relaxed Breathing