Respiratory system physiology

Netter FH, In Respiratory System A Compilation of Paintings Depicting Anatomy and Embryology, Physiology, Pathology, Pathophysiology, and Clinical Features and Treatment of Diseases (Eds Divertie MB, Brass A), pp. 46-59. CIBA Pharmaceutical Company, Summit, NJ, 1980. 

Contemporary anesthetic management requires (1) rapid loss of consciousness, which eliminates awareness, memory of pain, anxiety, and stress throughout the surgical period (2) a level of analgesia sufficient to abohsh the reflex reactions to pain, such as muscular movement and cardiovascular stimulation (3) minimal and reversible influence on vital physiological functions, such as those performed by the cardiovascular and respiratory systems (4) relaxation of skeletal muscle to facilitate endotracheal intubation, provide the surgeon ready access to the operative field, and reduce the dose of anesthetic required to produce immobihty (5) lack of... 

Casida JE, Toia RF. Organophosphorus pesticides their target diversity and bioactivation. In Dekant W, Neumann HG, eds. Tissue Specific Toxicity Biochemical Mechanisms. London Academic Press, 1992. Coburn RF, Forman HJ. Carbon monoxide toxicity. In Fahri LE, Tenney SM, eds. Flandbook of Physiology, The Respiratory System, Section 3, Vol. IV, Bethesda, MD American Physiology Society, 1987. Ellenhorn MJ, Barceloux DG. Medical Toxicology, New York Elsevier, 1988. 

Anatomy and physiology. The human respiratory system is divided into upper and lower respiratory tracts. The upper respiratory system consists of the nose, nasal cavities, nasopharynx, and oropharynx. The lower respiratory tract consists of the larynx, trachea, bronchi, and alveoli, which are composed of respiratory tissues. 

Red phosphorus is not considered to be harmful physiologically. White phosphorus burns the skin and eyes and causes severe internal damage if swallowed. The vapor from burning phosphorus irritates the respiratory system and eyes. Prolonged absorption of small quantities results in anemia, intestinal weakness, and bone and liver damage. Avoid contact with skin and eyes.3 TLV-TWA (yellow phosphorus) 0.1 mg/m3.30... 

Safety pharmacology studies investigate potentially undesirable effects of the drug compound on the physiological function of the central nervous system, the respiratory system, and the cardiovascular system. Some of the topics investigated are ... 

INFLAMMATORY AND IMMUNE RESPONSES AND RESPIRATORY, CARDIOVASCULAR, REPRODUCTIVE, AND NERVOUS SYSTEM PHYSIOLOGY. In all of these systems, the effects are mediated through a receptor(s) located on the plasma(s) membrane of responsive cells. Usually the biological effects noted are directly associated with stimulated cells or tissues. There is also support for the presence of PAF (and certain analogs) in normal tissues, with examples being the brain, uterus, lung, and the glandular stomach. 

The other approach is indirect, namely, to measure not enzymes as such, but their physiological biochemical efficacy. This can be achieved by oral administration of a composite test substance, which is hydrolyzed ( digested ) into its components exclusively by a specific pancreatic enzyme and subsequently absorbed and eliminated by the renal or the respiratory system. Ideally, the urinary excretion/respiratory exhalation of a metabolite of the test substance is proportional to its hydrolysis in the small intestine, which in turn is directly dependent on the quantity of pancreatic enzymes present. 

Particles much greater than 5 to 10 pm in diameter are usually removed by the upper respiratory system, and those smaller than 5 pm can penetrate deep into the alveolar spaces of the lung. Thus 5 to 10 pm is often considered to be the upper diameter for aerosols of physiological interest. 

The methods the USEPA uses in the derivation of inhalation RfDs are similar in concept to those used for oral RfDs however, the actual analysis of initiation exposures is more comple.x tlian oral e. posurcs due to (1) the dynamics of the respiratory system and its diversity across species, and (2) difTcrcnces in the physiochcmical (both physical and chemical) properties of contaminants. Although the identification of the critical study and the determination of the NOAEL in theory are similar for oral and inlralalion e.xposures, several important differences should be noted. In selecting the most appropriate study, the USEPA considers differences in respiratory anatomy and physiology, as well as differences in the physicochemical characteristics of tire contaminant. Differences in respiratory anatomy and physiology may affect the pattern of contaminant deposition in the respiratory tract, and the clearance and redistribution of the agent. Consequently, the different species may not receive the same dose of the contaminant at the same locations within the respiratory tract even though both species were exposed to the same particle or gas concentration. Differences in the physicochemical characteristics of the contaminants, such as the size and shape of a particle or whether the contaminant is an aerosol or a gas, also influence deposition, clearance, and redistribution. 

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