From the Research
The lungs perform several critical non-respiratory functions, including acid-base balance regulation, blood reservoir, blood filter, immune defense, hormone regulation, body temperature regulation, and water balance, as highlighted in recent studies such as 1. These functions are essential for maintaining overall physiological homeostasis and are often overlooked in favor of the lungs' primary role in gas exchange. The lungs' ability to regulate acid-base balance through the elimination of carbon dioxide is crucial for maintaining blood pH, and their role as a blood reservoir allows them to store approximately 500 mL of blood that can be mobilized during exercise or emergencies. Additionally, the lungs function as a blood filter, trapping small blood clots before they can reach vital organs like the brain, and play a role in immune defense through specialized cells and mucus production that trap and eliminate pathogens. The lungs also participate in hormone regulation by converting angiotensin I to angiotensin II, which affects blood pressure, and by metabolizing or activating other hormones like prostaglandins and serotonin, as discussed in studies such as 2. Furthermore, the lungs help regulate body temperature through water vapor loss during exhalation and assist in water balance by eliminating approximately 400 mL of water daily through respiration. These diverse non-respiratory functions are vital for maintaining overall physiological homeostasis and are supported by recent research, including a study published in 2016 1, which highlights the metabolic functions of the lung and their importance in maintaining homeostasis. Other studies, such as 3, also emphasize the lungs' role in regulating homeostasis and their "strategic" position in the blood circulation system. Overall, the lungs' non-respiratory functions are essential for maintaining overall health and are supported by a range of scientific evidence, including recent studies such as 1 and 2.