The lungs: structure and function explained

Doctor with X-ray of lungs

The lungs are one of the most important organs in the body. Through them, oxygen enters the blood and then all other organs. But how exactly does the process work? We show you the anatomy of the lung, its function and what happens to it when it is damaged.

Structure – where do the lungs sit and what do they look like??

Together with the trachea, the lungs form the lower respiratory tract. It almost completely fills the chest cavity (thorax) and is protected by the ribs. The lungs consist of two lung lobes, whereby the left one – on the heart side – is slightly smaller than the right one. Each lung is in turn divided into several lobes: two on the left, three on the right. The exact lung volume, i.e. the maximum amount of air a person can breathe in, varies from person to person and can be roughly determined using a rule of thumb.

How to calculate your lung volume:
Body size in meters times 2.5 = lung volume in liters 2

Infographic cross section nose to lungs

Anatomy: How the lungs are structured?

The structure of the lungs resembles an upside-down tree: the trachea, about twelve centimeters long, forms the trunk. It divides into two main bronchi that enter the two lungs. There they branch out further into the bronchi and the smaller bronchioles. They finally end in the alveoli (alveoli). The diaphragm is located directly below the lungs. The muscle-tendon plate separates the thoracic cavity from the abdominal cavity and, through its contraction, carries out the respiratory movement. The pleura visceralis surrounds the lungs, while the pleura parietalis lines the thorax. Together, the thin, smooth moist skins form the pleura. Between them there is a gap filled with fluid (pleural cavity or pleural space). It ensures that the lung lobes are always in contact with the thorax and can move along it at the same time.

Bronchial tree

The branches of the lung tree: bronchi and bronchioles

The bronchi and bronchioles form a system of tubes that pass air through the lungs. Inside, the bronchi and bronchioles are covered with a mucus-producing skin. Millions of tiny cilia are located there. They are covered by secretions to which inhaled pollutants and pathogens can adhere. The targeted movements of the cilia set the respiratory secretion in motion and remove the above-mentioned noxious substances.

Alveoli: Essential for oxygen supply

At the end of the bronchioles sit the alveoli (alveoli). They have a diameter of about 0.1 to 0.2 millimeters. Each of the bronchiolar ends has 40 of these outpouchings, or alveoli. This makes a total of 400 million alveoli. The finest pulmonary vessels surround the alveoli. The walls of the alveoli and vessels are very thin, so that blood can be seen shimmering through them. This is where gas exchange takes place. A scant second at most, during which time oxygen particles must enter the blood vessels and carbon dioxide must leave. Even when the lungs are fully exhaled, a certain amount of air remains in the alveoli as a buffer. During physical exertion, such as sports for example, a tooth is added to it. Nearly 300 millimeters of oxygen enter the blood every minute – that’s comparable to the size of a beer glass.

Function of the lungs – how does the oxygen supply in the body work?

The job of the lungs is to supply the body with oxygen. This is done via the alveoli. The inhaled oxygen is supplied to the blood through them and carbon dioxide (CO2) is released into the exhaled air. This process is called gas exchange and ensures the supply of oxygen to the entire body. As described, the respiratory tract and blood circulation unite in the area of the alveoli. Tiny blood vessels come into contact with the thin alveolar walls, allowing oxygen and carbon dioxide to exchange between the air we breathe and our blood. The oxygen absorbed into the blood is transported via the bloodstream to the body’s cells, where it contributes to energy production. At the same time, the lungs have the function of removing the waste products of respiration (especially carbon dioxide) into the air.

Bronchial diseases can be detected and the course of the disease assessed with the aid of various lung tests.

Interesting facts about respiration

Normally, breathing works unconsciously. It is automatically controlled by the nervous system. There is a separate breathing center in the brain for this. At rest, a person needs about six to nine liters of air per minute, but during physical exertion the demand can rise to up to 100 liters. 5

The air we breathe contains for the most part Nitrogen (about 78 percent), oxygen (about 21 percent) and Argon (about 1 percent). Other components are water vapor as well as trace gases (for example carbon dioxide and methane). 6

How in detail the absorption of oxygen in the lungs works

The Gas exchange takes place in the alveoli and regulates the oxygen supply to the body. Here’s how it works:

  1. The heart pumps oxygen-depleted blood from the body into the lungs.
  2. The oxygen-depleted blood flows past the alveoli of the lungs.
  3. Oxygen leaks through the thin walls of the alveoli into the blood vessels.
  4. The oxygen-depleted blood can thus take up fresh oxygen at the alveoli.
  5. At the same time, the blood releases carbon dioxide into the alveoli.
  6. Oxygen is distributed throughout the body via the bloodstream. Carbon dioxide is exhaled.

The gas exchange follows a so-called concentration gradient: If the proportion (concentration) of oxygen in the inhaled air is higher than in the blood flowing past, oxygen migrates into the blood. Conversely, carbon dioxide enters the alveoli when the CO2 concentration in the blood is higher than in the air we breathe.

Disease, age and co.: What lung changes occur?

Various triggers can lead to lung changes. These include diseases such as asthma, bronchitis and pneumonia, external influences such as smoking and particulate matter, but also increasing age. The result is often impaired function of the lungs, which is accompanied by various complaints – such as coughing or shortness of breath.

Lung changes due to diseases

Diseases can cause the lungs to change structurally. These include:

  • Asthma
  • Bronchitis
  • Pneumonia
  • Pulmonary fibrosis
  • Pulmonary emphysema
  • Pulmonary hypertension (pulmonary hypertension)
  • Bronchial carcinoma/lung cancer

Chronic obstructive pulmonary disease (COPD), for example, is accompanied by symptoms such as coughing, shortness of breath and mucus production, as well as structural lung changes. This in turn can lead to increased susceptibility to bacterial infections, such as streptococci.

Lung changes due to external influences

Smoking is the most common external cause of lung changes. Almost a quarter of all adults in Germany smoke. As a result, lung function steadily declines. Around 90 percent of all lung cancer-related deaths in men (80 percent in women) are attributable to smoking. 9

What is the effect of smoking on the lungs??

  • Destruction of the cilia on the bronchial mucosa
  • Reduced self-cleaning of the lungs
  • promotes inflammation
  • Airway constrictions
  • reduced oxygen supply to the brain
  • further symptoms such as cough, sputum and shortness of breath
  • increased risk of cancer
  • weakens the immune system

Another external factor influencing lung changes is particulate matter. In the case of pneumoconiosis, inorganic (mineral and metallic) dust is deposited in the respiratory tract when inhaled. From there, they are transported with the blood to other organs and can cause inflammation. This increases the risk of heart attack, stroke or cardiac arrhythmia. 10 This can also aggravate pre-existing conditions such as asthma or COPD. 11

Lung changes in old age

With increasing age the structure and tissue of the lungs change. In the course of life reduces the number of alveoli continuously and decreases until the age of 80. The incidence of streptococcus increases by about 30 to 50 percent between the ages of. 12

What lung changes happen with age?

  • Less elastic fibers in the lungs
  • more difficult expansion and contraction of the lungs
  • Lower oxygen uptake into the blood

In addition, the immune system is often weakened with age. Making the lungs more susceptible to infection. Due to the process of aging, lung infections occur more often, including chronic bronchitis or COPD.

Can the lungs regenerate by themselves?

Basically, the lungs can clean themselves. There are several ways to do this:

  1. Mucociliary clearance: Dust particles deposit on the bronchial mucosa. Through metachronous movements, the cilia transport them away. With the respiratory secretion they are eventually coughed up or swallowed.
  2. Phagocytic uptake: The alveoli have so-called scavenger cells (alveolar macrophages). They trap the dust particles and render them harmless by chemical decomposition.

Disease, age or external influences can destroy the lung tissue. The New formation of cells in the lungs However, works poorly compared to other organs. However, through positive habits you can Regenerate your lungs support. These include adequate exercise and abstaining from nicotine.

Senior couple jogging in the park

The airways have a self-cleaning mechanism. Read up on how you can support him with the right behavior!

Lung structure is reminiscent of an upside down tree. The trachea is the trunk from which the main bronchi branch off like two branches into the lungs. Bronchi and bronchioles form smaller branches, alveoli the leaves.

The lungs are responsible for supplying oxygen to the body. As gas exchanges in the alveoli, inhaled oxygen enters the blood and travels to the other organs. Spent oxygen is converted to carbon dioxide (CO2) and exhaled.

Smoking can lead to structural changes in the lungs and is the most common cause of lung cancer. 13 In addition, the lungs age more rapidly in smokers. The sooner a person stops smoking, the better he or she can stop this development.

With age, the number of alveoli, which are responsible for gas exchange, decreases. As a result, the performance of the lungs deteriorates, which can lead to reduced exercise tolerance and increased susceptibility to infections.

The lungs, though normally good at cleaning themselves. However, if the cells responsible for this are damaged, lung regeneration usually functions only to a limited extent. It is therefore important to strengthen the lungs at an early stage through positive behavior. Sufficient exercise and abstaining from nicotine are indispensable for this.

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