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The alveoli are tiny air sacs in the lungs where gas exchange takes place. The mean number of alveoli in a human lung is 480 million. [11] When the diaphragm contracts, a negative pressure is generated in the thorax and air rushes in to fill the cavity. When that happens, these sacs fill with air, making the lung expand.
V – ventilation – the air that reaches the alveoli; Q – perfusion – the blood that reaches the alveoli via the capillaries; The V/Q ratio can therefore be defined as the ratio of the amount of air reaching the alveoli per minute to the amount of blood reaching the alveoli per minute—a ratio of volumetric flow rates.
TLC: Total lung capacity: the volume in the lungs at maximal inflation, the sum of VC and RV. TV: Tidal volume: that volume of air moved into or out of the lungs in 1 breath (TV indicates a subdivision of the lung; when tidal volume is precisely measured, as in gas exchange calculation, the symbol TV or V T is used.)
There are two main categories of respirators: the air-purifying respirator, in which respirable air is obtained by filtering a contaminated atmosphere, and the air-supplied respirator, in which an alternate supply of breathable air is delivered. Within each category, different techniques are employed to reduce or eliminate noxious airborne ...
Human–machine system is a system in which the functions of a human operator (or a group of operators) and a machine are integrated. This term can also be used to emphasize the view of such a system as a single entity that interacts with external environment.
At the air inlet, air temperature must be lower than the upper ambient rating of the fan (typically 50 °C/122 °F). The position of air intake is at a point where the least amount of dust, oil, and moisture collects. Fail safe shutters protect the instrument if the purge air supply fails. These are key in systems where the flue gas is under ...
A computer monitor provides a visual interface between the machine and the user. Human–computer interaction (HCI) is research in the design and the use of computer technology, which focuses on the interfaces between people and computers.
HEPA filters are designed to arrest very fine particles effectively, but they do not filter out gasses and odor molecules. Circumstances requiring filtration of volatile organic compounds, chemical vapors, or cigarette, pet or flatulence odors call for the use of an activated carbon (charcoal) or other type of filter instead of or in addition to a HEPA filter. [20]