Describe the key factors that determine where a gas and a pa

Describe the key factors that determine where a gas and a particle react or become deposited in the pulmonary system.



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Describe the key factors that determine where a gas and a particle react or become deposited in the pulmonary system.

Solution

Pulmonary system is one of the primary routes for entry of a compound or a gas into the body. Everyday we inhale billions of particles and gas mixtures from the ambient air. Our lungs interact with the outside environment through breathing. The lungs in the pulmonary system has large surface areas and an extremely thin air-blood barrier. Suspended particles and harmful gases in the air enter the lungs while breathing and may have deleterious effects on health. Key factors determining this process includes physical characteristics of particles/ gas (like size, shape and density which determines its transport properties,), particle behavior in gas flow (like condensation, evaporation, and hygroscopicity), reactivity of gas or particle and also the patterns of gas flow in the respiratory tract (diffusion, deposition etc).

Particle deposition in the respiratory tract is dependent not only upon its diameter, density, shape, charge, and surface properties of the particles but also the breathing patterns of an individual. Particles are transported towards the surfaces of the respiratory tract by the process of sedimentation, impaction, and diffusion. Deposition of particle may occur in the extrathoracic and upper bronchial airways through which the inhaled air passes at high speed. Depositions in the lower bronchial airways as well as the gas exchange region are governed by the sedimentation process. Thus depending upon various physical and chemical properties, the deposition of particles may occur in four regions of the respiratory tract; extrathoracic, upper bronchial, lower bronchial, and alveolar region.

Gases diffuse from air into the lungs and then through the blood stream travel to various parts of the body. The diffusion and absorption of gases occur in a bidirectional manner. Gases get absorbed into the mucus or surfactant layer or the dissolved gases can escape back to the air in the lungs, depending upon their concentration gradient. While transport through the blood stream, the gases tend to react chemically. If the gas has high aqueous solubility and lower resistance of mucus and tissue layers of terminal bronchioles, its absorption is quicker.