Lungs: How do they function?

Lungs: How do they function?

The most important function of the lungs is to take and transfer oxygen from the environment to the bloodstream.

The lungs affect every part of our bodies and health, taking over 6 million breaths every year.

This article examines the form and function of the lungs, diseases affecting the lungs and how to maintain healthy lungs.

important facts about the lungs

  • The left and right lungs are different sizes.
  • The lungs play a part in many functions, including regulating the acidity of the body.
  • Smoking tobacco is the biggest cause of lung-related complaints.
  • Preventive and lifestyle measures can help keep the lungs healthy.


The human lungs diagram
The lungs not only enable us to breathe and talk, but they also support the cardiovascular system and help maintain pH in the body, among others

The lungs are in the chest, on either side of the heart, behind the rib cage. With a rounded point at their apex and a flatter base where they meet the diaphragm, they are roughly conical in shape.

The lungs are not equal in size and shape although they are a pair.

The left lung has a bordering indentation where the heart resides, which is called the cardiac notch. The right lung is shorter to allow space for the liver below.

Overall the left lung has a weight and capacity slightly lower than the right.

Two membranes, known as the Pulmonary Pleurae, surround the lungs. The inner layer lines the outer surface of the lungs directly, and the outer layer is attached to the rib cage’s inner wall.

Pleural fluid fills the space between the two membranes.


A spirometry test can show how well the lungs are working.
A spirometry test can show how well the lungs are working.

The main role of the lungs is to bring air out of the atmosphere and to pass oxygen into the bloodstream. It circulates from there on to the rest of the body.

Help is needed for proper respiration from structures outside the lungs. In order to breathe, we use the diaphragm muscle, the intercostal muscles (between the ribs), the abdomen muscles, and sometimes even the neck muscles.

The diaphragm is a muscle that lies beneath the lungs and is domed at the top. It poweres most of the breathing work involved.

As it contracts, it moves down , allowing more space in the chest cavity and boosting the capacity of the lungs to expand. When the volume of the chest cavity increases, the inside pressure decreases, and air is sucked in through the nose or mouth and down into the lungs.

As the diaphragm relaxes and returns to its position of rest, the volume of the lung decreases as the pressure within the cavity of the chest increases and the lungs expel the air.

The lungs are akin to bellows. Air is sucked in as they expand for oxygen. During exhalation the exchanged carbon dioxide waste is pushed back out as they compress.

It travels down the trachea when air enters the nose or mouth, also called the windpipe. After this, it reaches a section called the carina. The windpipe splits into two at the carina, creating two bronchi of the master stem. One of them leads to the left lung, the other to the right lung.

From there, the pipe-like bronchi split into smaller bronchi, and then even smaller bronchioles, like branches on a tree. This ever decreasing pipework finally ends in the alveoli, which are small endings of the air sac.

Here exchange of gas takes place.

The alveoli

The alveoli are the end point from which the oxygen passes from the outside world to the depths of the lungs.

Alveoli are minute sacs that are microscopic in size, each wrapped in a fine mesh of capillaries.

 Every human has around 700 million alveol individual. The total membrane surface area given by the alveoli is 70 meters squared. This is often spoken of as being around half a tennis court.

Between the lungs the body receives oxygen to the other tissues from the bloodstream as it passes through the circulatory system.

The blood that has given up its oxygen from the tissues in exchange for carbon dioxide then passes through the heart and travels to the lungs to reach the capillaries that surround the alveoli.

The alveoli now contain a new supply of oxygen in which the person has breathed. The oxygen passes into the bloodstream via a membrane called the alveolar-capillary membrane.

Simultaneously, the carbon dioxide accumulated in the bloodstream during its travels across the body reaches the alveoli. Upon exhalation, it is breathed back out into the atmosphere from there.

Put simply, carbon dioxide comes out as the oxygen goes in. This is an exchange of gas. 

Surfactant in the lungs

Special cells in the alveoli produce a compound known as pulmonary surfactant. It contains lipids, protein , and carbohydrates.

Surfactant has regions hydrophilic as well as hydrophobic. Water tends to attract hydrophilic regions, and the water repulses hydrophobic regions.

The surfactant pulmonary serves a number of vital functions.

These include:

  • allowing for better breathing efficiency
  • preventing the alveoli from collapsing on themselves

Each alveolus is like a wet-inside plastic bag. If no surfactant exists, the bag would collapse in on itself and the internal sides would stick together. Surfactant preven these alveoli from happening.

Pulmonary surfactant fulfills its role by reducing the surface tension. By doing so, it reduces the effort needed to inflate the alveoli.

Surfactant production does not start until the later weeks of gestation, before birth.

That’s why preterm born babies have respiratory problems, referred to as infant respiratory distress syndrome (RDS).

Other functions of the lungs

Respiration is the best-known role of the lungs, but they carry out other important functions.

pH balance: Too much carbon dioxide can cause the body to become acidic. If the lungs detect a rise in acidity, they increase the rate of ventilation to expel more of the unwanted gas.

Filtering: The lungs filter small blood clots, and they can remove small air bubbles, known as air embolisms, if they occur.

Protective: The lungs can act as a shock absorber for the heart in certain types of collision.

Protection from infection: Certain membranes within the lungs secrete immunoglobulin A. This protects the lungs from some infections.

Mucociliary clearance: The mucus that lines the respiratory passages traps dust particles and bacteria. Tiny hair-like projections, known as cilia, move these particles upward to a position where they can be coughed out or swallowed and destroyed by the digestive system.

Blood reservoir: The lungs can vary how much blood they contain at any moment. This function can be useful, for example, during exercise. The amount of blood the lungs can contain can vary from 500 to 1,000 milliliters (ml). The lungs interact with the heart and can help the heart function more efficiently.

Speech: Without airflow, humanity would be without its favorite pastime.

Respiratory disease

Respiratory diseases can affect any part of the respiratory tract, from the upper respiratory tract to the bronchi and down into the alveoli.

Respiratory system disorders are common. There are millions of common cold cases in the USA every year.

Inflammatory lung diseases

Asthma affects the lungs and breathing.
Asthma affects the lungs and breathing.

This group includes:

  • asthma
  • cystic fibrosis
  • acute respiratory distress syndrome
  • chronic obstructive pulmonary disease (COPD), including emphysema and chronic bronchitis

COPD generally results from the damage to the lungs caused by tobacco smoking.

Asthma includes obstructive narrowing and swelling of the airways, and excess mucus development. This causes breath- and wheezing shortness.

Triggers include:

  • tobacco and wood smoke
  • dust mites
  • air pollution
  • cockroach allergens
  • mold
  • stress
  • infections
  • some foods

No one understands exactly why asthma affects some and not others.

Restrictive lung diseases

This means that the airway is restricted.

It can happen as a result of:

  • the lungs becoming stiff
  • a problem with the chest wall or breathing muscles, for example, as with idiopathic cystic fibrosis
  • a curvature of the spine
  • obesity

The amount of air a person can intake is reduced and it becomes harder to breathe in.

Respiratory tract infections

Infections can happen in the respiratory tract at any point. Those could be defined as:

Upper respiratory tract infection: Common cold (viral) is the most commonly contracted. These include laryngitis, pharyngitis, tonsillitis and others.

Lower respiratory tract infection: Bacterial infection is the most common type, and bacterial pneumonia is the most common. Other causes of lower respiratory tract infection include viruses and fungi.

These types of infections can lead to complications including lung abscesses and the spread of infection to pleural cavity.


Tumors of the respiratory system can be malignant or benign.

Malignant tumors: 14 percent of all new cancer diagnoses are primary lung cancer. Lung cancer is the second most common cancer type, and the leading cause of cancer fatality in both men and women.

Cigarette smoking is the cause of most lung cancers. The blood in the body flows into the lungs from the heart, so that the cancer can spread easily to other parts of the body.

Benign tumors: Benign tumors are a less common cause of breathing disorder. Hamartoma is one example. These can compress tissue around them, but are typically asymptomatic.

Pleural cavity diseases

The pleural cavity is the gap between the pleural membranes inside and outside, which encase the outside of the lungs.

Pleural effusion: In the pleural cavity, fluid builds up, often due to cancer in or around the chest cavity. It could also be related to congestive heart failure or liver cirrhosis. Other causes include pleura inflammation which may occur with an infection.

Pneumothorax: For example, this can result from a trauma, a wound to the bullet. Air inside the pleural cavity is known as pneumothorax. This compresses the lungs, and causes them to collapse like a balloon when severe.

Pulmonary vascular disease

Vascular pulmonary diseases affect the vessels which carry blood through the lungs.

Examples include:

Pulmonary artery embolism: A blood clot forms elsewhere in the body and travels in the bloodstream to the heart and then to the lungs, where it becomes lodged. This can lead to sudden death. More rarely an embolism may be fat, amniotic fluid, or air.

Pulmonary arterial hypertension: Increased pressure may build in the arteries of the lungs. The explanations for this are still unclear.

Pulmonary edema: The most frequent result from congestive heart failure. Fluid leaks from capillaries into the alveolar air spaces.

Pulmonary hemorrhage: capillaries damaged and inflamed can leak blood into the alveoli. Coughing up the blood can be a symptom.

Tips for good lung health

Ways of keeping the lungs healthy include:

Quitting smoking
Not smoking is the key to avoiding many lung-related problems.

Stopping smoking: first and second hand cigarette smoking can lead to lung cancer and COPD, including chronic bronchitis and emphysema. Smoking causes the airways to narrow, inflames the lungs, and over time destroys the tissues. Make your home an area that’s smoke free.

Prevent infection: ways to prevent the spread of respiratory infections include washing hands, avoiding crowds during the flu season, and asking your health care provider for vaccinations for influenza and pneumonia.

Exercise: Aerobic exercise improves lung capacity and the ability to stay fit can prevent other diseases that could affect the lungs.

Check-ups: regular health checks can detect problems in the early stages, even if they feel well, when treatment is easier.

Avoiding exposure to pollutants: Chemicals used in garden or home can harm the lungs. When using heavy chemicals wear a mask. Radon is a naturally occurring compound that has been related to 21,000 deaths in the USA annually from lung cancer. S. For those people around 2,900 have never smoked.

Moisture control: Use exhaust fans and vents to keep indoor humidity down to an acceptable level. Whenever necessary keep wet surfaces clean and dry. It is a safe idea to keep the house ventilated with natural fresh air.