What primarily drives the body's urge to breathe?
Lack of oxygen
Activity of the respiratory muscles
Need for АТР
Accumulation of carbon dioxide
The Correct Answer is D
A. Lack of oxygen: While low oxygen levels (hypoxemia) can stimulate breathing, peripheral chemoreceptors respond to hypoxia mainly when oxygen drops significantly. In healthy individuals, oxygen levels are usually sufficient, so hypoxia is not the primary driver of the normal respiratory urge.
B. Activity of the respiratory muscles: Respiratory muscles, such as the diaphragm and intercostals, execute breathing but do not generate the neural drive for ventilation. Their activity is a result of signals from the respiratory centers rather than the cause of the urge to breathe.
C. Need for ATP: Cellular ATP demand indirectly influences respiration by increasing metabolic rate, which produces more carbon dioxide. However, the body’s primary immediate cue to adjust ventilation is not ATP itself, but the byproducts of metabolism, particularly carbon dioxide.
D. Accumulation of carbon dioxide: Rising carbon dioxide levels in the blood increase hydrogen ion concentration, lowering pH and stimulating central chemoreceptors in the medulla. This feedback mechanism is the main driver of the body’s urge to breathe, prompting faster and deeper respiration to maintain acid-base balance and remove CO₂ efficiently.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Pleural cavity: The pleural cavity is the potential space between the parietal pleura (lining the thoracic wall) and the visceral pleura (covering the lungs). It contains a small amount of lubricating fluid that reduces friction during lung expansion and contraction, allowing smooth respiratory movements while maintaining negative pressure to facilitate lung inflation.
B. Bronchial space: The bronchial space refers to the lumen of the bronchi through which air passes. It is not a cavity between pleural layers and does not play a role in pleural fluid dynamics or lung expansion.
C. Alveolar cavity: Alveolar cavities are microscopic air spaces within the lungs where gas exchange occurs. They are internal to the lung tissue and do not exist between the pleural layers.
D. Thoracic cavity: The thoracic cavity is the large compartment of the chest housing the lungs, heart, and major vessels. While it contains the pleural cavities, it is not specifically the space between the parietal and visceral pleurae.
Correct Answer is A
Explanation
A. Heme: Heme is the iron-containing component of hemoglobin responsible for binding oxygen molecules. Each hemoglobin molecule contains four heme groups, and the iron ion at the center of each heme binds one oxygen molecule, allowing hemoglobin to transport oxygen efficiently from the lungs to peripheral tissues.
B. Collagen: Collagen is a structural protein found in connective tissues, skin, and bones. It does not participate in oxygen transport or bind oxygen and is unrelated to hemoglobin function.
C. Myosin: Myosin is a motor protein in muscle tissue responsible for contraction and movement. It has no role in oxygen transport or hemoglobin structure.
D. Globin: Globin refers to the protein chains (alpha and beta) of hemoglobin that provide structural support and influence hemoglobin’s shape and function. While essential for hemoglobin stability, globin does not directly bind oxygen; that role is performed by the heme groups.
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