Bronchitis What Is Bronchitis Lung Health

The lungs are two organs used for breathing that are located in the chest, one on the right side and one on the left side. Each lung is divided into lobes, which are further divided into sub-parts called lobules. The right lung has three lobes, while the left lung has only two lobes. The left lung also has a cardiac notch, which accommodates the heart.

The lungs bring oxygen to the blood from the atmosphere and remove carbon dioxide from the blood, expelling it into the atmosphere. This process is accomplished by millions of tiny cells that form tiny air sacs, called alveoli.

Aside from respiratory function (breathing), the lungs also have non-respiratory functions.

Respiratory Functions of the Lungs

Respiration in humans occurs in many steps. First, air is brought in through the airways, which consist of:

  • the bronchioles
  • the larynx
  • the nose
  • the pharynx
  • the trachea (also known as the windpipe).

The air enters the lungs and the alveoli, which allow for gas exchange.

Next, an assortment of capillaries, or very fine blood vessels, allow blood to be transported over the alveoli. While the blood is flowing over the alveoli, oxygen is diffused into the blood from the alveoli, and carbon dioxide is diffused out of the blood and into the alveoli.

This process occurs using muscular action. The diaphragm and other muscles alter volume and pressure to introduce air into the airways. (This is also known as inspiration.) When people are breathing normally, expiration of air does not need this process and is passive. The process of inspiration and expiration of air is also known as ventilation.

What is Vital Capacity?

Vital capacity refers to the maximum amount of air a person can exhale after inhaling their maximum amount. Measuring vital capacity with a medical device called a spirometer can help medical professionals diagnose problems with the lungs or respiratory function.

Non-Respiratory Functions of the Lungs

In addition to bringing air into the body and supplying the body with oxygen and ridding it of carbon monoxide, the lungs also:

  • filter out small blood clots in the veins and any gas bubbles that occur in the bloodstream during SCUBA diving or similar activities
  • have an influence on the amount of medication or drugs in the blood
  • nearly enclose the heart, providing a layer of protection and acting as a shock absorber for the heart.


Bronchitis is an inflammation of the lung and can be either acute or chronic. Acute bronchitis is usually the result of bacteria or a virus, while chronic bronchitis is associated with chronic obstructive pulmonary disease.

Bronchitis interferes with normal, healthy lung function by producing a persistent cough and phlegm and by obstructing the airways. It often causes shortness of breath or wheezing.

Understanding how the lungs work can help people realize when something is wrong with respiratory function and when they should seek medical help.

When Things Go Wrong in the Lungs

Because the lungs are very moist, they create a prime environment for bacteria to grow. Many respiratory illnesses, such as bronchitis, are the result of bacteria growth or the presence of a virus in the lungs.

However, in a sense, lungs are overbuilt. They have a very high reserve volume compared to actual oxygen requirements, which is why activities that are damaging to the lungs, such as years of smoking, often do not make a noticeable difference in the lungs for a long period of time.


MedicineNet (2007). Lungs. Retrieved July 11, 2007, from the MedicineNet Web site: