At a PO2 of 70 mm Hg and normal temperature and pH, hemoglobin is ________ percent saturated with oxygen.

Correct Answer: D

Rationale: The correct answer is D (more than 90). At a PO2 of 70 mm Hg, hemoglobin is more than 90% saturated with oxygen due to the high oxygen affinity of hemoglobin at this partial pressure. Hemoglobin exhibits near-maximal saturation at this level, promoting efficient oxygen binding and transport. Choices A, B, and C are incorrect as they do not accurately reflect the high oxygen saturation levels associated with a PO2 of 70 mm Hg.

Correct Answer: D

Rationale: The correct answer is D because all the choices are structural features of the trachea. A is correct as the trachea has C-shaped cartilage rings for structural support. B is correct as the trachea contains smooth muscle fibers that help regulate airflow. C is correct as the trachea is lined with cilia that help sweep mucus and foreign particles out of the respiratory tract. Therefore, all of the above choices are structural features of the trachea, making D the correct answer.

Correct Answer: A

Rationale: The correct answer is A: alveoli. Alveoli are tiny air sacs in the lungs where gas exchange occurs. Oxygen from the air we breathe diffuses into the blood, and carbon dioxide from the blood diffuses into the alveoli to be exhaled. The pharynx, larynx, and trachea are parts of the respiratory system but do not participate in gaseous exchange. The pharynx serves as a passage for air and food, the larynx houses the vocal cords, and the trachea carries air to and from the lungs. Only the alveoli have the thin walls and large surface area necessary for efficient exchange of gases.

Correct Answer: C

Rationale: The correct answer is C: Breathing. Pulmonary ventilation refers to the process of breathing, which involves both inhalation and exhalation. Inhalation is the act of taking in air, while exhalation is the act of expelling air. Therefore, the term "pulmonary ventilation" encompasses both inhalation and exhalation, making choice C the correct answer. Choices A and B are incorrect because they only represent one part of the breathing process. Choice D is incorrect because it suggests that all choices are correct, which is not accurate in this context.

Correct Answer: A

Rationale: The correct answer is A: Distended neck veins. This finding indicates potential right-sided heart failure, a complication of COPD called cor pulmonale. The nurse should address this immediately to prevent further deterioration. Distended neck veins suggest increased central venous pressure and impaired right heart function. Left lower quadrant tenderness (B) is unrelated to COPD. Urinary output of 40 mL/hr (C) is within normal range. Excessive coughing (D) is a common symptom of COPD but does not indicate an immediate complication.