FUNCTIONS OF THE LUNGS

Mechanism of Breathing
 Breathing is a process that occurs automatically in a state of sleep even though the karma of the respiratory system is affected by the autonomic nervous system. According to the site of the respiratory gas exchange can be divided into two types, namely breathing out and breathing deeply. Breathing out is the air exchange that occurs between the alveolar air to blood in the capillaries, whereas deep breathing is breathing that occurs between the blood in the capillaries with the body's cells. Coming and the air in the lungs are affected by differences in air pressure within the chest cavity with air pressure outside the body. If the pressure outside the chest cavity larger then the air will enter. Conversely, if the pressure in the chest cavity larger then the air will keluar.Sehubungan the organ involved in the intake air (inspiration) and the expenditure of air (expiration), the respiratory mechanism divided into two kinds, namely respiratory chest and abdominal breathing. Chest and abdominal breathing to occur simultaneously.

a. Chest breathing 
    Chest breathing is the breathing muscle that involves the ribs between bones. The mechanism can be  distinguished as follows.
1. Phase Inspiration 
This phase of muscle berkontraksinya ribs between bones so that the chest cavity enlarges, resulting in pressure within the chest cavity to become smaller than the pressure outside so that the oxygen-rich air outside the entrance. 
2. Expiratory phase 
This phase is the phase relaxation or muscle between the ribs return to their original position which was followed by a decline in the ribs so that the chest cavity becomes smaller. As a result, the pressure inside the chest cavity becomes larger than the outside pressure, so air in the chest cavity is rich in carbon dioxide out.
b. Abdominal breathing 
    Abdominal breathing is a breathing mechanism involves the activity of the muscles of the diaphragm which limits the abdominal cavity and chest cavity. Abdominal breathing mechanism can be divided into two phases namely as follows: 
1. Phase Inspiration 
In this phase of the diaphragm muscle to contract so that the diaphragm is horizontal, consequently the chest cavity enlarges and becomes small so that the air pressure outside the entrance. 
2. Expiratory phase 
Expiratory phase is the phase berelaksasinya diaphragm muscle (back to its original position, inflate) so that the chest cavity decreases and the pressure becomes greater, consequently the air out of the lungs.

Lung Volume
 
On the left image is written four volumes of the lung. When everything is added together, equal to the maximum lung volume expands. Explanation of each volume are as follows:
1. Tidal volume (VT) is the volume of air inspired or diekspirasi each time normal breathing; size of approximately 500 milliliters.
2. Inspiration reserve volume (Irv) is the extra volume of air that can be inspired after and above the normal tidal volume inspiration when performed strongly with a maximum contraction of the diaphragm, m. intercostalis externi, and accessory muscles of inspiration; usually reaches 3000 milliliters.
3. Expiratory reserve volume (ERV) is the maximum volume that can be extra air through the expiratory diekspirasi strong at the end of expiration is not normal; normal number is about 1100 milliliters.
4. Residual volume (RV) is the volume of air that still remain in the lungs after expiration most powerful; volume is the amount of approximately 1200 milliliters. Residual volume can not be measured with a spirometer because the volume of air is not in and out of the lungs.

Lung Capacity
 1. Inspiration capacity (IC) is equal to the reserve volume plus the tidal volume inspiration. This is the amount of air (roughly) 3500 milliliters can be inhaled by a person, starting at the normal expiration and lung development up to a maximum.
2. Functional residual capacity (FRC) with expiratory reserve volume plus the residual volume. This is the amount of air remaining in lungs at the end of normal expiration (about 2300 milliliters).
3. Vital capacity (VC) as the inspiration reserve volume plus the tidal volume and expiratory reserve volume. This is the maximum amount of air a person can be expelled from the lungs after first filling the lungs to the maximum and then spend as much (about 4600 milliliters). This value provides useful information about the strength of respiratory muscles and other aspects of lung function.
4. Total lung capacity (TLC) is the maximum volume that can develop lung as possible with inspiration as hard as possible (about 5800 milliliters) is equal to the amount of vital capacity plus the residual volume.