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cofactor · 2
←Iron
Loading oxygen in the lungs and unloading it in the tissues depends on two properties of hemoglobin: once it binds one oxygen, the next binds more easily, and it releases oxygen more readily in tissues rich in carbon dioxide and slightly acidic (the Bohr effect). Iron sits at the center of hemoglobin, so with iron deficiency the lungs are fine; there are simply fewer carriers.
Immune cells in the lungs use an antimicrobial peptide called LL-37 against pathogens, and vitamin D raises its expression; this is one mechanism linking vitamin D to airway defense. A meta-analysis of individual participant data found that vitamin D supplements had some effect on asthma attacks.
regulates · 6
Chronic low oxygen (as in chronic obstructive pulmonary disease or sleep apnea) makes the blood vessels in the lungs constrict; over time this causes pulmonary hypertension, forces the right ventricle to thicken, and can end in cor pulmonale, heart failure driven by lung disease. Cardiovascular disease is one of the major causes of death in people with chronic lung disease.
Breathing shapes the brainstem's control of the autonomic nerves through the carbon dioxide and acidity of the blood, sensed by chemoreceptors, and through stretch receptors in the lungs. Long-term carbon dioxide retention (as in severe chronic lung disease) may affect attention and mood; overbreathing causes dizziness, tingling hands and a racing heart and is easily mistaken for a panic attack.
The blood's acid-base balance is kept by the lungs and kidneys together: the lungs adjust quickly by breathing out carbon dioxide, and the kidneys adjust slowly by keeping or excreting bicarbonate. When chronic obstructive pulmonary disease causes carbon dioxide retention, the kidneys hold on to more bicarbonate to compensate; when kidney failure causes acidosis, breathing becomes deep and rapid (Kussmaul breathing).
The smaller the particle, the more easily it slips past the layered defences of the nose and airways and reaches the alveoli deep in the lung, and the finest fraction may cross the alveolar wall into the blood. Burnett 2018 estimated with a model that long-term exposure to outdoor PM2.5 is linked to a large number of deaths worldwide.
←Nasal Breathing & Mouth Taping
The paranasal sinuses continuously produce a little nitric oxide (NO), which travels down into the lungs with each breath in and slightly widens only the small vessels beside the alveoli that have just received fresh air, so air and blood flow are matched more closely. In the small experiments of Lundberg 1996, healthy people had higher blood oxygen tension breathing through the nose than through the mouth, and arterial oxygen rose in intubated patients when air from their own noses was fed back in; how much this contributes in everyday breathing is still unsettled, and mouth breathing bypasses this nitric oxide altogether.
Vitamins C and E and the carotenoids together form the lung's antioxidant network, but the benefit from the diet as a whole is modest. A single nutrient at a high dose backfired: in the ATBC trial, beta-carotene supplements raised lung cancer in smokers by 18%.