The nurse is caring for a patient who has just returned to the unit after a colon resection. The patient is showing signs of hypoxia. The nurse knows that this is probably caused by what?

Correct Answer: D

Rationale: The correct answer is D: Shunting. Hypoxia after a colon resection is likely due to shunting, which is a condition where blood bypasses the normal oxygenation process in the lungs, leading to decreased oxygen levels in the blood. Shunting can occur due to factors such as collapsed alveoli or blood vessel blockages. Nitrogen narcosis (A) is not related to hypoxia but rather occurs in scuba divers exposed to high partial pressures of nitrogen. Infection (B) may cause fever and inflammation but is not the primary cause of hypoxia in this scenario. Impaired diffusion (C) refers to issues with gas exchange in the alveoli and is not the most likely cause of hypoxia after a colon resection.

Correct Answer: B

Rationale: The correct answer is B, lower respiratory tract. The larynx and structures distal to it, such as the trachea, bronchi, and lungs, are part of the lower respiratory tract. The upper respiratory tract (choice A) includes the nose, nasal cavity, pharynx, and larynx. Internal respiratory tract (choice C) is not a commonly used term in respiratory anatomy. Alveoli of the respiratory tract (choice D) specifically refer to the air sacs in the lungs where gas exchange occurs, not the entire respiratory division that includes the larynx and structures distal to it.

Correct Answer: B

Rationale: The correct answer is B (45 mm Hg) because the partial pressure of carbon dioxide in the interstitial space of peripheral tissues is around 40-45 mm Hg. This value is higher than in the arterial blood (around 40 mm Hg) due to the production of CO2 by tissues. Choice A (35 mm Hg) is too low for interstitial CO2 levels. Choice C (55 mm Hg) and D (70 mm Hg) are too high and not consistent with normal physiological values. Overall, the correct answer aligns with the typical range of interstitial CO2 pressure in peripheral tissues.

Correct Answer: A

Rationale: Step 1: Increased PO2 leads to higher oxygen levels in blood. Step 2: Higher PO2 causes hemoglobin to become fully saturated with oxygen. Step 3: Fully saturated hemoglobin stores more oxygen. Step 4: Therefore, as PO2 increases, saturation goes up and hemoglobin stores more oxygen. Other choices are incorrect because they do not align with the relationship between PO2, hemoglobin saturation, and oxygen storage in the blood.

Correct Answer: A

Rationale: The correct answer is A because at birth, when an infant takes their first breaths, blood flow to the lungs increases due to the expansion of the pulmonary vasculature. This allows for proper oxygenation of the blood. Choice B is incorrect as the resistance in the pulmonary arteries decreases to accommodate the increased blood flow to the lungs. Choice C is incorrect as changes in blood flow do cause the foramen ovale to close, ensuring proper circulation. Choice D is incorrect as air entering the alveoli is essential for oxygen exchange to occur in the lungs.