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There is approximately 10% replacement of alveolar air per normal breath. This maintains very constant O2 and CO2 levels in the alveoli.
The total lung capacity depends on the person's age, weight, sex and the degree of physical activity. For example, females tend to have a 20-25% lower capacity than males. Tall people tend to have a larger total lung capacity than shorter people. Heavy smokers have a drastically lower capacity than nonsmokers. Lung capacity is also affected by altitude. A person who is born and lives at sea level will have a smaller lung capacity than a person who spends their life at a high altitude. This is because there is less oxygen in the air at altitude, so the lungs gradually expand to process more air. When someone from sea level travels up to the higher parts of the earth (eg. the AndesSee also architecture with non-sequential dynamic execution scheduling (ANDES). Please note that the geology in this article reflects views from the first decade of the 20th century. It is a good example of the descriptive geology of that time, but becaus, Mexico CityMexico City ( Spanish: Ciudad de Mexico known in Pre-Columbian times as Tenochtitlan is the capital of Mexico; it geographically spans both the Mexican Federal District and part of the state of Mexico, to the north of the Federal District. Mexico City is, TibetThis article is on Historic Tibet. Tibet" can also refer to the Tibet Autonomous Region. Tibet ( Tibetan : , (Bod) pronounced Po, Chinese: , pinyin: Xizang) is a region of Central Asia and the home of the Tibetan people. With an average elevation of 4,900 and the Himalayas) they will often develop a condition called altitude sicknessAltitude sickness (also: acute mountain sickness (AMS) or altitude illness is a pathological condition that is caused by lack of adaptation to high altitudes. It commonly occurs above 2,440 metres (8,000 feet). The symptoms are headaches, fatigue, shortne because their lungs cannot process enough oxygen for their bodies needs.
The tidal volume, vital capacity, inspiratory capacity and expiratory reserve volume can be measured directly with a spirometerA spirometer is an apparatus for measuring the volume of air inspired and expired by the lungs. It is a precision differential pressure transducer for the measurements of respiration flow rates. The spirometer records the amount of air and the rate of air. Determination of the residual volume is more difficult (a given percentage of inert gas is added to the breathed air, and the amount by which it is diluted is used to calculate the volume in which it was diluted.)
These are the basic elements of a ventilatory pulmonary function test. The results can be used to divide pulmonary diseasese into restrictive diseases, in which the volumes are decreased, and obstructive disease, where volumes are essentially normal but flow rates are impeded.
There are four basic measured lung volumes:
From these volumes, several important capacities are also calculated:
Respiratory quotient = RQ = rate of CO2 production/rate of O2 consumption. RQ can vary with diet and exercise, but under typical conditions, RQ = 0.8.
Following is a list of average partial pressures of Oxygen gas (torr) for a human at rest:
Only ~ 7.5% of lung air is changed over on one breath at rest.
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