Which of the following gas mixture is used by Divers to prevent Oxygen toxicity

Correct Answer: B

Rationale: The correct answer is B: Oxygen and Nitrogen. This gas mixture is used by divers to prevent Oxygen toxicity because it closely mimics the composition of the air we breathe. Oxygen toxicity can occur at high partial pressures of Oxygen, which can lead to seizures and other serious health issues. Choices A, C, and D are incorrect because CO2 and rare gases are not typically used in diving gas mixtures, and including CO2 in the mixture can increase the risk of Oxygen toxicity. Nitrogen is used as a diluent to reduce the partial pressure of Oxygen, making it safer for divers.

Correct Answer: B

Rationale: The correct answer is B: First thing in the morning. Sputum should be collected in the morning because it is usually more concentrated, making it easier to obtain a good sample. This is important for accurate analysis and identifying potential pathogens causing the patient's symptoms. Collecting sputum immediately after a meal may result in contamination with food particles. At bedtime, sputum may have accumulated overnight, but morning samples are still preferred due to concentration. Collecting sputum after a period of exercise may introduce respiratory secretions not reflective of the underlying condition.

Correct Answer: C

Rationale: To calculate pulmonary ventilation rate, multiply tidal volume by respiration rate. In this case, 500 mL * 14 bpm = 7,000 mL/min. Converting to liters, it's 7 L/min. Choice A is incorrect as it miscalculates the conversion from mL to L, B is incorrect due to incorrect calculation, and D is incorrect as it's not the accurate result of the multiplication.

Correct Answer: A

Rationale: Step 1: Blood flow supplies oxygen and removes carbon dioxide in the lungs, essential for efficient gas exchange. Step 2: Decreased blood flow means less oxygen delivery and carbon dioxide removal, leading to decreased respiratory efficiency. Step 3: Choice A is correct as it directly impacts the gas exchange process. Summary: - Choice B (increased surface area) would enhance gas exchange efficiency. - Choice C (increased partial pressure gradients) would improve gas exchange efficiency. - Choice D (increased gas solubility) would not directly affect respiratory efficiency.

Correct Answer: C

Rationale: The correct answer is C because the Dorsal Respiratory Group (DRG) and Ventral Respiratory Group (VRG) are the centers in the brainstem responsible for controlling the rate and depth of breathing. The DRG primarily regulates inspiration, while the VRG is involved in both inspiration and expiration. The apneustic and pneumotaxic centers (choices A and B) are subregions within the pons that modulate the activity of the DRG and VRG but do not establish the baseline rate and depth of breathing. The expiratory center (choice D) is responsible for controlling only the expiratory phase of breathing and is not involved in setting the normal rate and depth of breathing.