Nokea
In human beings, partial pressure of carbon dioxide in the inspired and expired air is respectively
- A. 0.3 and 40 mm Hg
- B. 0.3 and 32 mm Hg
- C. 40 and 46 mm Hg
- D. 40 and 0.3 mm Hg
Correct Answer: B
Rationale: The correct answer is B (0.3 and 32 mm Hg) because in inspired air, the partial pressure of carbon dioxide is low at around 0.3 mm Hg, whereas in expired air, the partial pressure of carbon dioxide is higher at around 32 mm Hg due to gas exchange in the lungs.
Choice A (0.3 and 40 mm Hg) is incorrect because the partial pressure of carbon dioxide in inspired air is not typically as high as 40 mm Hg.
Choice C (40 and 46 mm Hg) is incorrect because the values are reversed; the partial pressure of carbon dioxide is higher in expired air compared to inspired air.
Choice D (40 and 0.3 mm Hg) is incorrect as the values are reversed, and the partial pressure of carbon dioxide in inspired air is not typically as high as 40 mm Hg.
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Which ion is formed as a result of the action of carbonic anhydrase on carbon dioxide and water?
- A. Sodium ion (Na+)
- B. Bicarbonate ion (HCO3-)
- C. Hydroxide ion (OH-)
- D. Potassium ion (K+)
Correct Answer: B
Rationale: Step 1: Carbonic anhydrase catalyzes the reaction between carbon dioxide (CO2) and water (H2O).
Step 2: This reaction forms carbonic acid (H2CO3).
Step 3: Carbonic acid then dissociates into bicarbonate ion (HCO3-) and hydrogen ion (H+).
Step 4: Therefore, the ion formed as a result of the action of carbonic anhydrase on CO2 and H2O is the bicarbonate ion (HCO3-).
Summary:
- Choice A (Sodium ion) is incorrect as it is not involved in the reaction with carbonic anhydrase.
- Choice C (Hydroxide ion) is incorrect as it is not a product of the reaction but rather a different compound.
- Choice D (Potassium ion) is incorrect as it is not related to the reaction between carbon dioxide and water.
A SCUBA diver has been deep underwater and suddenly rises to the surface too fast. Why does the diver get decompression sickness?
- A. Pressure decreases and carbon dioxide rushes into cells
- B. Pressure changes too fast and the carbon dioxide in the blood forms bubbles
- C. Pressure decreases too fast and nitrogen gas in the blood forms bubbles
- D. The gas in the SCUBA tank had too much pressure and rapid ascent forces too much air into the blood
Correct Answer: C
Rationale: The correct answer is C because as the SCUBA diver rises too fast, the pressure decreases rapidly. This causes the nitrogen gas that was dissolved in the blood at high pressure to form bubbles, leading to decompression sickness. Choice A is incorrect because carbon dioxide rushing into cells is not the cause of decompression sickness. Choice B is incorrect because it refers to carbon dioxide forming bubbles in the blood, which is not the mechanism of decompression sickness. Choice D is incorrect because it focuses on excess air from the SCUBA tank entering the blood, which is not the primary reason for decompression sickness.
A male adult patient on mechanical ventilation is receiving pancuronium bromide (Pavulon), 0.01 mg/kg I.V. as needed. Which assessment finding indicates that the patient needs another pancuronium dose?
- A. Leg movement
- B. Finger movement
- C. Lip movement
- D. Fighting the ventilator
Correct Answer: D
Rationale: The correct answer is D: Fighting the ventilator. This indicates inadequate muscle relaxation, requiring another dose of pancuronium. Leg, finger, and lip movements are not reliable indicators of muscle relaxation in a mechanically ventilated patient. Fighting the ventilator suggests the patient is not adequately sedated or paralyzed, requiring further intervention to maintain optimal ventilation and oxygenation.
You are supervising a student nurse who is performing tracheostomy care for a client. For which action should you intervene?
- A. The student nurse suctions the tracheostomy tube prior to performing tracheostomy care.
- B. The student nurse removes old dressings and cleans off excess secretions.
- C. The student nurse removes the inner cannula and cleans using universal precautions.
- D. The student nurse replaces the inner cannula and cleans the stoma site.
Correct Answer: A
Rationale: The correct answer is A. Suctioning prior to tracheostomy care is incorrect because it increases the risk of introducing infection. Removing old dressings and cleaning secretions (B), removing and cleaning the inner cannula (C), and replacing the inner cannula and cleaning the stoma site (D) are standard steps in tracheostomy care.
Mammalian lungs have numerous alveoli for
- A. Increasing the volume of inspired air
- B. Keeping the lungs in proper shape
- C. Higher number of muscles to provide greater elasticity
- D. Increasing surface area for gaseous diffusion
Correct Answer: D
Rationale: The correct answer is D because alveoli increase the surface area for gaseous diffusion, facilitating efficient exchange of oxygen and carbon dioxide in the lungs. Alveoli are tiny air sacs where gas exchange occurs. Option A is incorrect as alveoli do not affect the volume of inspired air. Option B is incorrect as alveoli do not play a role in maintaining lung shape. Option C is incorrect as alveoli do not increase muscles in the lungs for elasticity. Therefore, the primary function of alveoli is to increase surface area for gaseous diffusion, making option D the correct choice.