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From the base to the apex of lungs: Your guide to this organ

Apex of lung: cropped headshot of an African-American male

Key takeaways:

  • Oxygen enters while carbon dioxide exits from the base to the apex of the lung.
  • The lungs are the principal organs in the respiratory system.
  • Lung cancer is the deadliest of all cancers. In 2020, lung cancer killed an estimated 135,720 patients.
  • The best way to minimize the risk of developing lung cancer is to avoid cigarette smoke and air pollution.
  • Prevention routine using low-dose CT scan can help. 

Your lungs keep you alive, propelling you through life by facilitating the exchange of life-giving oxygen and carbon dioxide with the air that surrounds us. 

From the base to the apex of the lung, this article will tell you everything you need to know about the anatomy of the lungs, why you need to take good care of this fascinating organ, and how to protect it from lung disease and lung cancer. 

The anatomy of the lung.

Apex of lung: 3D illustration of the lungs

The lungs are pyramid-shaped organs that come in a pair. They are located in the mediastinum, which is the central compartment of the thorax around the heart. The lungs are connected to the trachea – or windpipe – by the right and left bronchi.  

A thin, bilayered membrane called pleura wraps the lungs. The pleural membrane has two layers: a visceral pleura that covers the thorax’s inside and a parietal pleura that covers the lungs.

The apex of the lung is located where the upper lobe begins, while the base of the lungs is by the diaphragm, where the costal surface borders our ribcage. 

Each lung is divided into separate units known as lobes, which are separated by fissures.

  • The right lung is split into three lobes: the superior, middle, and inferior. 
  • The left lung is split into two lobes: the superior and the inferior.

Every lobe contains multiple bronchopulmonary segments, each receiving blood from its artery and air from its tertiary bronchus.

The diaphragm borders the lungs at the base, a flat muscle shaped like a dome that separates the abdominal and chest or thoracic cavities. It contracts and relaxes as we breathe. 

The vagus nerve dictates airway tone, blood perfusion or irrigation, and mucus secretion. The vagus nerve is involved in lung diseases.

Interestingly enough, although they’re a pair, the lungs are asymmetrical: Your right lung is shorter and broader than the left. However, there is an indentation on the left lung’s surface known as the cardiac notch. This area creates space for the heart.

The bronchi, blood vessels, and nerves enter the lungs via a central wedge-shaped region called the hilum. 

The bronchi branch into smaller bronchioles, creating subdivisions of the lobes called pulmonary lobules. And each pulmonary lobule has its own large bronchiole with multiple branches. Every lobule is separated from one another by a wall of connective tissue called an interlobular septum.

What is the function of the lungs?

Apex of lung: Female medical worker wearing protective mask looking at the camera

The lungs are essential parts of the respiratory system. Cells need oxygen to keep their metabolism going, and humans have an efficient and complex system for doing this.

The red blood cells transport the oxygen molecules via an organized blood vessel network. The final destination of oxygen is the intracellular mitochondria. These organites are also called the cellular lungs.

You need oxygen to do practically everything, and you create carbon dioxide as a waste byproduct. Your lungs are responsible for ridding your body of carbon dioxide and getting your body the oxygen it needs.

The blood in your lungs’ capillaries facilitates oxygen and carbon dioxide gas exchange, an essential bodily function.

The pulmonary artery, or the aorta, carries deoxygenated blood to the alveoli, tiny air sacs in the lungs that allow quick gas exchange, thanks to an extremely thin membrane.

As the pulmonary artery follows the bronchi, it branches over and over again, becoming increasingly smaller. As the pulmonary arteries become closer to the alveoli, they become the pulmonary capillary network made of thin-walled, tiny vessels that mirror the bronchioles and alveoli structure enabling oxygen and carbon dioxide diffusion.

This diffusion occurs because of a difference in concentration. Molecules will diffuse through the membrane until the concentrations reach an equilibrium.

The respiratory membrane is formed where the capillary and alveolar walls meet and the blood becomes oxygenated. Afterward, newly oxygen-enriched blood is drained from the alveoli through the pulmonary veins and exits the lungs. It is then transported throughout the body, carrying oxygen to the places it needs to go and allowing us to function correctly.

What are lung diseases?

Nurse assisting a patient undergoing CT scan

Like any other organs, the lungs are sites of pathologies. Because the inner membrane is in contact with the outside world, the lung tissue is exposed to various volatile pollutants and infectious agents. 

You may be at risk of developing lung diseases if:

  • You are actively smoking (cigarettes, chimney, combustion).
  • You are a second-hand smoker (regularly breathing smoke from others).
  • You are exposed to asbestos or other carcinogens (arsenic, chromium, and nickel).
  • You are exposed to radon gas (natural uranium breakdown occurring in the soil, rock, water).
  • You are infected by bacteria (Mycobacterium Tuberculosis, for instance).
  • You are infected by viruses such as influenza, coronaviruses related to the common cold, and COVID.
  • You have been previously exposed to radiation (previous X-ray therapy to the chest).
  • You have a family history of lung cancer (your risk of developing lung cancer increases if your parents, siblings, or kids have one).

Lung cancer.

While bacteria and viruses could cause pneumonia, smoke and asbestos are the main risk factors in developing lung cancer.

Just in the US, about 228,820 new cases of lung cancer were expected in 2020. Overall, 1 in 15 men will be diagnosed with lung cancer in their lifetime. Such cancer occurs mainly in people over 65 years old but can develop many years earlier.

When lung cancer is detected at an early stage, the chance of survival is 61%. However, this survival rate drops to 6% when it spreads to the lymph nodes via the lymphatic vessels.

The best way to avoid thinking about this is to take care of your lungs early on. Quitting smoking altogether would go a long way to prevent cancer, even if you started smoking decades ago.

Other lung diseases.

Once pathogens like bacteria, viruses, or vapors manage to enter your lungs, they can trigger inflammation with harmful consequences:

  • Acute respiratory distress syndrome (ARDS). ARDS is a serious pulmonary condition that is mainly caused by pneumonia and sepsis. It is an acute and progressive inflammation inside your lung, resulting in a decrease in the lung’s surface necessary for gas exchange. Just by itself, ARDS affects about 10% of intensive care unit patients worldwide.
  • Chronic obstructive pulmonary disease (COPD). This severe condition is a chronic disease. It usually takes place after repetitive episodes of ARDS. Every year, COPD accounts for 3.2 million deaths worldwide

How can you prevent lung cancer?

Your lung health is vital to your overall health. You need to take good care of them by being as proactive as you can.

A healthy lifestyle, i.e., one that lacks smoking and includes a healthy diet and daily exercise, may help prevent cancer. But low-risk doesn’t mean zero risks. Take our five-minute questionnaire to understand your risk of cancer.

At Ezra, you can get an annual low-dose CT scan. It can help to detect lung cancer and other lung abnormalities early so you can treat them effectively. The scan is painless, fast, affordable, and can save your life.

It’s beautiful to see how our lungs work together to create a living, breathing, healthy organism capable of so much. Talk to your doctor and book a scan now.