A patient with a history of smoking two packs of cigarettes a day for the past 20 years says that he is not alarmed by his cough. He says, "I get this cough and spit up mucus every winter." The nurse recognizes these symptoms as being suggestive of:

Correct Answer: A

Rationale: The correct answer is A: Chronic bronchitis. The patient's history of smoking for 20 years and persistent cough with mucus production every winter are indicative of chronic bronchitis. Chronic bronchitis is characterized by inflammation of the bronchial tubes due to irritants like smoking, leading to excessive mucus production and persistent cough. Emphysema is characterized by destruction of lung tissue, not necessarily accompanied by mucus production. Sarcoidosis is a systemic inflammatory disease affecting multiple organs, not specifically related to the symptoms described. Diffuse interstitial fibrosis involves scarring of lung tissue, typically presenting with a dry, non-productive cough.

Correct Answer: D

Rationale: The correct answer is D: bicarbonate ions. When carbon dioxide is produced by the body, it combines with water in the blood to form carbonic acid. This carbonic acid then dissociates into bicarbonate ions and hydrogen ions. The majority of the carbon dioxide is transported in the blood as bicarbonate ions, which are more soluble and can easily travel to the lungs where they are converted back into carbon dioxide for exhalation. Choices A, B, and C are incorrect because carbon dioxide is primarily transported in the form of bicarbonate ions, not as a gas, in blood plasma, or as potassium carbonate ions.

Correct Answer: C

Rationale: The epiglottis covers the glottis during swallowing to prevent food or liquid from entering the airway. This helps protect the lungs from aspiration. False vocal cords (A) are not directly involved in this process. True vocal cords (B) are responsible for producing sound and are located below the glottis. Adam's apple (D) is the laryngeal prominence formed by the thyroid cartilage and does not cover the glottis during swallowing. Therefore, the correct answer is C (epiglottis).

Correct Answer: D

Rationale: Emphysema is the correct answer because it is a condition where the alveoli walls break down, reducing the surface area for gas exchange in the lungs. This leads to difficulty in breathing. Asphyxia is suffocation due to lack of oxygen, not related to alveoli breakdown. Bronchitis is inflammation of the bronchial tubes, not alveoli damage. Asthma is a chronic condition affecting the airways, not specifically related to alveoli destruction. Therefore, emphysema is the most appropriate term for reduction in respiratory surface due to alveolar breakdown.

Correct Answer: B

Rationale: The correct answer is B (25%). In the lungs, oxygen binds to hemoglobin to form oxyhemoglobin. This increases the oxygen saturation of hemoglobin to around 97-98%. As blood travels to the tissues, oxygen is released from hemoglobin to be used by the cells. By the time blood returns to the lungs, only about 25% of the hemoglobin is still carrying oxygen. This is known as the oxygen saturation curve. Choice A (50%) is incorrect because the percentage of hemoglobin carrying oxygen drops significantly as blood travels to the tissues. Choice C (75%) is incorrect because by the time blood returns to the lungs, more than 25% of the hemoglobin has already released its oxygen. Choice D (100%) is incorrect because not all hemoglobin molecules carry oxygen at the same time; it depends on the oxygen tension in the environment.