Human lungs – Parts of respiratory system

Humans for respiration need a continuous supply of oxygen. Humans take in oxygen and leave out carbon dioxide, which is the poisonous waste product in the process of respiration. The lungs are essential respiratory organs in the human body.

The human anatomy consists of two lungs. They can be called as the left and the right lung, respectively. The left lung has two lobes while the right lung has three lobes. The lungs contain approximately 1500 miles of airways and about 300 to 500 million alveoli.
The total surface area is an approximate of 70m^2 (m-square) in a fully grown human body, (roughly the size of a badminton court).
An alveoli , also known as “little cavity”, is derived from the Latin word “alveolus”, and these are the terminal ends of a respiratory tree and are shaped like a hollow-cavity.

The average respiratory rates of a resting adult is about 10-20 breaths per minute. We spend about 1/3rd of a minute in inhaling.
The total breathing capacity, however depends on the individual, that is, it varies on factors depending on age, height, weight and sex.
It is observed that females tend to have a 20-25% lower breathing capacity than males, while tall people tend to have a larger lung capacity than shorter people. And people living in low-lined areas, that is, at the sea-level, tend to have a smaller lung capacity than those people living at a higher altitude.

People who smoke have a lower lung capacity than non-smokers.

Lungs function similar to that of bellows, which is a mechanical device that blows strong current of air. **Lungs convert the hormones that cause the narrowing of blood vessels and drives the blood pressure up and also remove the waste products in the blood.**
A lung is measured to be between 10-12 inches long. The two lungs are separated by a structure called “media sternum”. The lungs are covered by a structure known as the “pulmonary pleura”.

The lung is an important organ that performs various functions that happen every second of our lives, out of which breathing is considered to be the most essential. As previously mentioned, the lungs take in oxygen and give out carbon dioxide.
The air that we breathe in, enters the human body and reaches to the lungs through a windpipe , called trachea, which branches further into two main tubes which distributes the air supply to both the left and the right lung , respectively. These tubes further divide themselves into 22 times the number of branches resulting in the formation of more than 100,000 smaller tubes, called bronchioles, and about 300 million air sacs( or alveoli), which are only about a 0.3 mm in diameter. Since the walls of the alveoli are 1/50th the thickness of a tissue paper and are also covered up with millions of tiny blood vessels, called capillaries, there is a free-flow exchange of both, oxygen and carbon dioxide, between the body and the environment.

The lungs play an important role in the body’s defense against infection and other harmful environmental factors. Air that is inhaled either through the nose or the mouth may consist of various dust particles or infectious agents, and ended up getting stored in the lungs.
Mucus, which is a sticky liquid that is produced by the lungs, may trap the inhaled particles while the lung’s white blood cells , that serve as protective agents, aid in the engulfment and destruction of such harmful matter and bacteria. Hence one good alternative is to cough. Coughing helps clear the mucus and other materials from the lungs.

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