Which of the following statements correctly describes atmospheric pressure?
It only affects respiration during inhalation.
It is the force exerted by surrounding air and is typically 760 mmHg at sea level.
It is always lower than intrapleural pressure.
It fluctuates during the breathing cycle.
The Correct Answer is B
A. It only affects respiration during inhalation: Atmospheric pressure influences both inhalation and exhalation by creating the pressure gradient necessary for airflow. Limiting its effect to inhalation is inaccurate because it is a constant force acting on the body and lungs throughout the respiratory cycle.
B. It is the force exerted by surrounding air and is typically 760 mmHg at sea level: Atmospheric pressure is the weight of the air in the environment pressing on all surfaces. At sea level, it averages 760 mmHg and provides the baseline pressure against which intrapulmonary and intrapleural pressures are measured, driving air movement during breathing.
C. It is always lower than intrapleural pressure: In reality, intrapleural pressure is normally slightly negative relative to atmospheric pressure to keep the lungs inflated. Atmospheric pressure is generally higher than intrapleural pressure, so this statement is incorrect.
D. It fluctuates during the breathing cycle: Atmospheric pressure remains essentially constant during normal breathing. It is the intrapulmonary pressure that fluctuates with inhalation and exhalation, creating the gradient necessary for airflow, not the atmospheric pressure itself.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Decreased pH and increased oxygen release: Increased CO₂ production in tissues leads to the formation of carbonic acid, which dissociates into hydrogen ions, lowering blood pH. The Bohr effect describes how this acidic environment reduces hemoglobin’s affinity for oxygen, promoting oxygen release to meet the metabolic demands of tissues.
B. Increased hemoglobin affinity for oxygen: Elevated CO₂ and decreased pH actually reduce hemoglobin’s oxygen-binding affinity, facilitating oxygen unloading. An increase in affinity would prevent oxygen delivery to tissues, which contradicts the physiological purpose of the Bohr effect.
C. Increased pH and decreased oxygen release: The opposite occurs in the Bohr effect. CO₂ accumulation lowers pH rather than raising it, and this acidic shift enhances, rather than diminishes, oxygen release from hemoglobin to active tissues.
D. Reduced dissociation of oxygen from hemoglobin: Reduced oxygen dissociation would impair tissue oxygenation. The Bohr effect ensures that oxygen is more readily released in areas of high CO₂ and low pH, matching oxygen delivery to local metabolic activity.
Correct Answer is E
Explanation
A. Left primary bronchus: The left primary bronchus is longer, narrower, and more horizontally oriented than the right. Its angle and smaller diameter make it less susceptible to foreign body aspiration compared to the right bronchus.
B. Lobar bronchus of the left lung: Lobar bronchi are secondary branches within the lungs. While foreign bodies can lodge here, the initial aspiration usually occurs in the larger, more vertical right primary bronchus due to anatomical alignment with the trachea.
C. Segmental bronchus in the left lung: Segmental (tertiary) bronchi are smaller airways branching from lobar bronchi. Objects typically lodge in larger airways first, making initial lodging in left segmental bronchi less likely.
D. Segmental bronchus in the right lung: While possible, foreign bodies usually enter the larger right primary or lobar bronchi first. Segmental bronchi are smaller and further downstream, so initial aspiration into these branches is less common.
E. Right primary bronchus: The right primary bronchus is wider, shorter, and more vertical than the left, creating a direct path from the trachea. These anatomical features make it the most common site for aspirated foreign bodies, especially large objects like food particles.
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