NGR 5141 - Module 6 Questions and Answers () (Verified Answers).

Module 6 - Ch. 32, 33, 34 1. Distinguish between respiratory and cardiac causes of SOB. What is the physiologic rationale for serum test measurements of brain and atrial natriuetic peptide to determine the cause of SOB? Respiratory causes of shortness of breath include chronic obstructive pulmonary diseases like emphysema and bronchitis where the airway has increased mucus secretion or enlargement of gas exchange airways and destruction of alveolar walls. Asthma is also a respiratory cause of shortness of breath when the airway is narrowed. A pulmonary embolism may also cause shortness of breath due to the blockage of the airway by the clot. Cardiac causes of shortness of breath include acute coronary syndrome caused by a blockage in the coronary arteries. Congestive heart failure is another cause of respiratory shortness of breath which occurs due to excess fluid accumulation. This excess fluid which leaks into the lungs makes breathing difficult. Cardiac tamponade can also cause shortness of breath because the excess fluid surrounding the heart compresses it and it cannot fill adequately. The atrial natriuretic peptide is secreted from cells in the right atrium when right atrial blood pressure increase. The ANP causes increased urine sodium excretion which causes a decrease in blood volume and blood pressure. Brain natriuretic peptide is secreted from cardiac cells and also contributes to urinary sodium excretion. It is used as a marker for acute heart failure. Therefore, when these peptides are elevated, it leads to a cardiac etiology of shortness of breath due to fluid overload. 2. Explain the changes that occur in the pulmonary system with aging. Consider – compliance, structure of spine and thorax, total lung capacity, wall ventilation capacity, increased residual volumes, ventilatory reserves, and ventilation-perfusion ratios. PaO2, exercise tolerance, muscular strength. With increasing age, alveoli start to lose their wall tissue and capillaries. This results in diminishing alveolar surface area which is available for gas diffusion and decreases airway support. The chest wall compliance decreases due to the ribs becoming ossified and joints becoming stiffer. This causes the chest wall to not expand as well. Respiratory muscle strength and endurance also decrease. The vital capacity decreases and residual volume increases although the total lung capacity does not change. These changes decrease ventilatory reserves and cause decreased ventilation-perfusion ratios. PaO2 decreases with age due to structural and mechanical changes such as a loss of alveolar surface area and increased ventilation perfusion mismatch. The lowered PaO2 and diminished ventilatory reserve causes a decrease in exercise tolerance. Respiratory muscle strength and endurance also decrease with age, however, respiratory function varies from person to person. 3. Explain