Basics of nutrition: Respiratory system

March 17, 2024, 10:43 AM IST Lalit Kapoor in FIVE PILLARS OF HEALTH: A Blueprint for Wellbeing, Science, TOI

Last week, we discussed the Gastrointestinal Tract, which provides the essential nutrients our bodies need to sustain themselves. These nutrients require oxygen to metabolize and produce energy. The respiratory system is crucial in delivering fresh oxygen to the body and expelling carbon dioxide. While the respiratory system is also involved in sound production and the sense of smell, our focus here will be on the exchange of oxygen and carbon dioxide.

When we inhale through our nose or mouth, the air travels down the trachea into the lungs, where it divides into multiple branches called bronchioles, eventually reaching tiny sacs known as alveoli. The human lung contains over 600 million alveoli, with their combined surface area roughly equivalent to a tennis court.

Surrounding the alveoli are blood capillaries that carry blood from various body parts. This blood is rich in carbon dioxide and low in oxygen. Oxygen and carbon dioxide exchange occurs across the alveolar membrane and the capillary walls through diffusion. The picture below shows how an alveolar capillary exchanges carbon dioxide for oxygen. 

Diminished Surface Area

At birth, the surfaces of the alveoli and capillaries are pristine, maximizing gas exchange efficiency. However, over time, two significant changes occur. First, dust and pollutant particles accumulate on the alveolar lining, reducing the area available for gas exchange. Second, the capillaries’ inner linings develop plaque due to the consumption of inflammatory foods, further diminishing the available surface area. As we age, the reduction in surface area becomes more pronounced, leading to breathing difficulties, a condition known as Chronic Obstructive Pulmonary Disease (COPD).

It is important to understand that obstruction is happening on both sides of that one tennis court size surface of all 600 million plus alveoli of the lung. 

The obstruction on the capillary wall is due to atherosclerosis which is classified as a cardiovascular disease. 

The discomfort one experiences in breathing is due to the combination of these two phenomenons working together. 

Historically, main pollutants like dust and coal particles from wood and charcoal burning prompted people to seek cleaner air in sanatoriums as they aged.

Diminished Breathing Capacity

Breathing capacity is another crucial factor. The average lung holds about 6 liters of air, but only a fraction is used during normal breathing. This capacity, which varies among individuals and even within the same person over time, increases with physical activity. Enhancing respiratory capacity through active lifestyles can improve conditions like COPD, as physical activity can help revive some collapsed alveoli.

Symptoms of COPD include shortness of breath, wheezing, and a chronic cough. The cough is a mechanism by which body clears obstructions, but when these consist of fine particles, the condition becomes persistent. That is why it is called chronic. 

Nitric Oxide Gas to Rescue

Consuming green leafy vegetables and beetroots, which are high in nitrates, release nitric oxide in the blood vessels, aiding in the removal of atherosclerotic damage and improving gas exchange. These vegetables can be consumed as salad or green juice. Additionally, Pranayama breathing exercises like Bhastrika and Kapalbhati can help alleviate respiratory obstructions, offering benefits for those with respiratory conditions.

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