Lungs respiratory physiology

This chapter discusses the transport and absorption of ozone and other photochemical oxidants within the respiratory tract. It includes lung morphology and flow aspects of respiratory physiology and emphasizes methodologic approaches to modeling. 

FLOW ASPECTS OF RESPIRATORY PHYSIOLOGY Rcipiratoiy Airflow Patterns In Long Models versus the Real Lung... 

Various factors affect the reproducibility of drag delivery to the lungs, including physiological (respiratory maneuver) and pharmaceutical (device, formulation) variables. For the systemic delivery of drags with a narrow therapeutic index, such variations may be unacceptable. 

Having discussed relevant aspects of lung and airway structure that may influence the efficacy of aerosol therapy, it is important that we consider the potential impact of differences in respiratory function between individuals as a result of age, maturity, or clinical status. Particular problems may be encountered in delivering drugs to the respiratory tract of young children as a result of anatomic and physiological variations due to age (198). The most relevant aspects of respiratory physiology with respect to aerosol therapy include the... 

Taylor AE, Rehder K, Hyatt RE, Parker JC. Anatomy and function of the lung. In Taylor AE, Rehder K, Hyatt RE, Parker JC, eds. Clinical Respiratory Physiology. Philadelphia Saunders, 1989 3-24. 

Weibel ER. Lung morphometry and models in respiratory physiology. In Chang HK, Paiva M, eds. Respiratory Physiology An Analytical Approach. New York Marcel Dekker, 1989 1-56. 

In order for any inhaled solvent vapors to enter the blood circulation, they need to reach the alveoli, cross the gas-blood interface and dissolve in the blood. Gas is carried to the gas-blood interface by airways, while blood is carried by blood vessels. Since these functions take place in the lung, the essentials of respiratory physiology will be briefly reviewed. 

Simulations were performed by optimizing the setting parameters and modeled airflows. The pressure and lung volume profiles can be observed simultaneously and breathing patterns can also be obtained. The simulator imitates the software structure with the GUI interface manifestation. The respiratory physiology (Picoi and Vco ) " as firstly set while imitating with the respiratory mechanical characteristics Rrs and Ers under various loaded breathing. 

Heyder J, Blanchard JD, Feldman HA, Brain JD. Convective mixing in human respiratory tract estimates with aerosol boli. J Appl Physiol 1988 64 1273-1278. Paiva M, Engel L. Gas mixing in the lung periphery. In Chang HK, Paiva M, eds. Respiratory Physiology. An Analytical Approach. New York Marcel Dekker,... 

Widdicombe, J, G. (1977). Defense mechanisms of the respiratory tract and lungs. In International Review of Physiology Volume 14. Repiratory Physiology U (J. G. Widdicombe, Ed.), pp. 291-316. University Park Press, Baltimore. 

Physiological action Irritates respiratory tract injures lungs and eyes causes systemic poisoning... 

Tobias, J.M. 1945. The pathological physiology of the lung after phosgene. In Fasciculus on chemical warfare medicine v. II, respiratory tract. Washington, DC National Research Council, Committee on Treatment of Gas Casualties pp. 331—391. (Cited in EPA 1986)... 

Table 6.2 Physiological Parameters in Mouse, Rat, Rabbit and Human of Relevance to the Isolated Perfused Lung Preparation (Data from Davies and Morris, [24]). Respiratory Tidal Volume Can Be Calculated by Dividing Total Ventilation by Respiratory Rate.

Histamine also occurs naturally in plant tissues. It arises from the decomposition of histidine, but its function has not been elucidated. Histamine levels in some plants are surprisingly high - 1,340 pg/g in the blossoms of the spinach plant ( ). It is the exposure of man and animal to this botanical histamine with a possible physiological action that makes histamine of agricultural importance. The inhalation of cotton dust, for instance, has been related to byssinosis, a respiratory disease involving a lung dysfunction. 

Enhanced susceptibility to respiratory exposure to infectious agents is of considerable potential public-health significance. This has been reported to occur in mice exposed to ozone at as low as 0.08 ppm, the lowest reported effect concentration in laboratory animal studies. It seems essential, therefore, to continue and expand research on the effect of ozone and other photochemical oxidants on physiologic protective mechanisms of the lung. Appropriate dose-response studies should be included to confirm or establish the exposure concentration-time relationships that result in increased susceptibility to inhaled microorganisms, and studies of the cellular responses and mechanisms should be conducted with a view to providing methods that are applicable to epidemi-ol( c studies in oxidant-exposed human populations. 

These results show that retinyl esters in respiratory epithelium and in alveolar cells form a pool of vitamin A, which can be used physiologically by the tissue. The formation of retinol and at least RA from retinyl esters is strictly controlled. So far an unphysiological formation of RA and a subsequent toxicity seems not possible. Retinyl esters, however, are biochemically inert with respect to gene expression or vitamin A activity as long as they are not hydrolyzed. Consequently, the inhalative application, especially in cases of insufficient lung development, could represent a true alternative. The oral contribution is hardly successful because of the poor RBP s)mthesis of the liver and the lack of availability of a parenteral solution is currently not available. 

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