The lungs breathe life into the body. Every breath you take, as the Police sang, draws air into the lungs. From here oxygen is transferred into the blood for it to be delivered around the body to the organs that need it if they are to function properly, and to the cells if they, and we, are to survive. In fact, every part of the body needs oxygen: it’s the body’s life source. During this transfer process another exchange of gases takes place — the removal of a waste product, the ‘body’s exhaust’, carbon dioxide. Sitting comfortably on each side of the chest the two lungs are protected from external harm by the surrounding rib cage. Each lung is about the size of a football, and on average weighs in at around one pound.
At rest we breathe between 15 to 25 times every minute, more when exercising and less when asleep. We do this without even thinking about it. Amazing. For this to happen the breathing centre in the medulla of the brain constantly monitors how much oxygen is needed. Nerve signals travel from the brain to the muscles involved in breathing — the diaphragm and the intercostal muscles — triggering inhalation. Gases are exchanged inside the lungs. During inhalation the large dome-shaped muscle — the diaphragm that’s located below the lungs and separates the chest from the abdomen — contracts so its dome becomes flattened and pulled downwards. At the same time the intercostal muscles, which are fixed between the ribs, cause the ribs to flare outwards. Together these actions increase the size of the chest cavity. The spongy tissue of the lungs is very elastic and this allows them to expand when we breathe in and constrict when we breathe out. According to the British Lung Foundation, an estimated 10,000 litres of air is moved in and out of the lungs each day.
It helps to imagine the respiratory system as an upside-down tree. As we inhale air moves through the mouth and nose into the windpipe (trachea) or ‘trunk’, into the bronchi, formed as the trachea divides into two breathing tubes, or ‘boughs’, each going to one of the lungs. Air continues its journey into narrower tubes called bronchioles that branch off the bronchi, much like the branches of a tree, before reaching the tiny balloon-like air sacs called alveoli. Each lung contains around 300 million alveoli that are often described as looking like ‘small bunches of cauliflower heads’. It’s into these air sacs that the lung’s waste exhaust, carbon dioxide, passes from the blood, and from here that the life-giving oxygen passes from the air.
But oxygen and carbon dioxide exchange is not the only function the lungs perform. They also help to protect the body from the many germs that are carried in the air we breathe. They achieve this by trapping and moving these and other foreign matter out of the body before it has a chance to cause problems. Large particles are filtered out of the air by the nose. Any particles that get past this stage can be trapped in the mucus that’s produced by and coats the breathing tubes. These tubes are lined with tiny hairs (cilia) that in a wave-like motion sweep the combination of mucus and potentially harmful germs and other material back to the mouth. From here, without us having to do anything, it is swallowed into the stomach so it can leave the body further down the line. When the breathing tubes are irritated we may cough — another defence mechanism — to expel the germ-laden mucus from the body more quickly.
Despite this finely tuned and seamless process, things do go wrong. Irritants, such as cigarette smoke, can damage the cilia, leaving them less able to clear the mucus. Irritants may also trigger a protective mechanism in the lungs that in turn can cause problems. This occurs in asthma where in an attempt to try to protect the lungs, muscles in the breathing tubes constrict: this is called bronchospasm. The resulting narrowing of the breathing tubes makes it harder for a person to breathe and often results in wheezing.
In another common lung condition, chronic obstructive pulmonary disease (COPD), which is the umbrella term for diseases that include emphysema and chronic bronchitis, the airways in the lungs become inflamed and the alveoli become damaged. Inflamed airways are narrow, making breathing harder, and damaged, stiff and less elastic air sacs result in inadequate gaseous exchange. People with COPD often have what they call a ‘smoker’s cough’, find it difficult to breathe during exercise or at rest, and produce far more mucus than is usual. Smoking is the major cause of COPD.
The lungs are an amazing piece of kit that often do not receive the attention and recognition they deserve. Not smoking is the most important way to keep our lungs healthy. Smoking not only allows cancer-causing chemicals to get into the lungs, it also damages their cleaning and repair system by destroying the tiny hairs. Consequently, germs and chemicals from tobacco smoke are able to remain in the lungs increasing the risk of infection, lung damage and cancer.
Regular exercise helps maintain cardio-respiratory fitness. A healthy diet may help to keep the lungs healthy, especially when foods consumed are anti-oxidant rich, such as fruit and vegetables.
It’s also very important to protect the lungs from harmful particles that may be circulating in the air. Avoiding high levels of pollution where possible, and perhaps wearing a face mask when doing DIY or painting, for example. If symptoms persist, for example a cough that lasts more than three weeks, this should prompt a check-up with your doctor. And when someone already has a lung condition, such as asthma, it’s important to follow the treatment plan. This might include having a pneumonia vaccination and an annual flu jab to help reduce the risk of suffering the complications of flu. So, look after your lungs and any experience of Berlin’s 1980s hit ‘Take My Breath Away’ should be a good one.