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In a physiologic shunt there is mismatching of

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In aphysiologic shunt, there is mismatching of ventilation and perfusion within the lung.This results in insufficient ventilation to provide the oxygen needed to oxygenate theblood flowing through the alveolar capillaries. Physiologic shunting of blood usuallyresults from destructive lung disease that impairs ventilation or from heart failure thatinterferes with movement of blood through sections of the lungs.p.Chemoreceptors: automatic regulation of ventilation/breathing; monitor blood levels ofoxygen, carbon dioxide, and pH and adjust ventilation to meet the changing metabolic needs ofthe body
Input from these sensors is transmitted to the respiratory center, and ventilation isadjusted to maintain the ABGs within a normal range.Central chemoreceptors: extremely sensitive to short-term changes in PCO2 andrespond to changes in H+ concentrationAn increase in PCO2 levels produces an increase in ventilation that reaches itspeak within a minute or so and then declines if the PCO2 level remains elevatedPeripheral chemoreceptors: also monitor carbon dioxide, but play a much moreimportant role in monitoring oxygen levelslocated in the carotid and aortic bodiesq.Lung receptors: automatic regulation of ventilation/breathing; monitor breathing patterns andlung function (airway resistance and lung expansion)Stretch receptors: respond to changes in pressure in the walls of the airways. When thelungs are inflated, these receptors inhibit inspiration and promote expiration. They areimportant in establishing breathing patterns and minimizing the work of breathing byadjusting respiratory rate and VT to accommodate changes in lung compliance andairway resistanceIrritant receptors: stimulated by noxious gases, cigarette smoke, inhaled dust, and coldair. Stimulation of the irritant receptors leads to airway constriction and a pattern of rapid,shallow breathingJuxtacapillary or J receptors: sense lung congestion. These receptors may beresponsible for the rapid, shallow breathing that occurs with pulmonary edema,pulmonary embolism, and pneumoniar.Cheyne-Stokes breathing: a rare abnormal breathing pattern that can occur while awake butusually occurs during sleep. The pattern involves a period of fast, shallow breathing followed byslow, heavier breathing and moments without any breath at all, called apneas. Instead of anapnea, some people have periods of extremely shallow breathing, called hypopneas. After anapnea or hypopnea, the pattern begins again in a cycle that typically lasts 45 to 90 seconds.s.Dyspnea: a subjective sensation or a person’s perception of difficulty in breathing thatincludes the perception of labored breathing and the reaction to that sensationDyspnea is observed in at least three major cardiopulmonary disease states:Primary lung diseases, such as pneumonia, asthma, and emphysemaHeart disease that is characterized by pulmonary congestionNeuromuscular disorders, such as myasthenia gravis and muscular dystrophy,that affect the respiratory musclesFor some people, it only during exercise and is referred to as exercise-induced reactiveairway disorder or exercise-induced asthma.

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Term
Fall
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Bone marrow, Platelet

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