- AIt directly damages alveolar walls, reducing surface area for gas exchange.
- BIt binds irreversibly to carbonic anhydrase, impairing CO2 transport.
- CIt has a much higher affinity for hemoglobin than oxygen, forming carboxyhemoglobin.
- DIt increases the acidity of blood, leading to severe metabolic acidosis.
Carbon monoxide (CO) has an affinity for hemoglobin that is about 200-250 times greater than that of oxygen, forming stable carboxyhemoglobin and effectively preventing oxygen transport.
More Questions on Breathing and Exchange of Gases
In a patient with metabolic acidosis (e.g., due to uncontrolled diabetes), what compensatory respiratory response would be expected?
→ 2The nasal cavity plays a crucial role in conditioning inhaled air. Which of the following functions is *not* primarily associated with the nasal cavity?
→ 3Consider a scenario where the alveolar membrane thickness increases due to fluid accumulation (pulmonary edema). Which of the following would be the most immediate physiological consequence?
→ 4Which of the following is characterized by allergic reactions causing inflammation of bronchioles, leading to breathing difficulties?
→ 5A person has a tidal volume of 500 mL and a respiratory rate of 12 breaths per minute. If their anatomical dead space is 150 mL, what is their alveolar ventilation rate (AVR)?
→ 6In the blood, a small percentage of oxygen is transported in a dissolved state. What is the approximate percentage?
→ 7Assertion (A): The PO2 of arterial blood is a more potent regulator of respiration than PCO2. Reason (R): Peripheral chemoreceptors are more sensitive to changes in PO2 than central chemoreceptors.
→ 8Each molecule of hemoglobin can maximally bind to how many molecules of oxygen?
→ 9Without pulmonary surfactant, the work required to inflate the lungs would:
→ 10Which sequence represents the correct pathway for air entering the lungs?
→ 11Which of the following statements correctly describes the muscular activity during a forceful expiration?
→ 12The alveolar epithelium primarily consists of:
→ 13A patient presents with dyspnea, barrel chest appearance, and chronic cough. Spirometry shows a significantly increased Residual Volume (RV) and Total Lung Capacity (TLC), but reduced FEV1/FVC ratio. These findings are most consistent with:
→ 14Which of the following conditions would enhance the binding of oxygen to hemoglobin in the pulmonary capillaries?
→ 15A premature infant born with underdeveloped surfactant-producing cells would likely exhibit:
→ 16Functional Residual Capacity (FRC) is the volume of air:
→ 17A person is voluntarily holding their breath. Which of the following would eventually force them to breathe again?
→ 18During normal expiration, which of the following pressure relationships holds true?
→ 19The Haldane effect states that the deoxygenation of blood increases its ability to carry carbon dioxide. Which of the following best explains the underlying mechanism?
→ 20Which of the following forms transports the largest percentage of CO2 in the blood?
→ 21A patient sustains a severe injury resulting in paralysis of the diaphragm. Which of the following would be the most immediate and significant consequence?
→ 22The fluid in the pleural cavity serves to:
→ 23Arrange the following steps of oxygen transport from the alveoli to the tissue cells in the correct sequence: 1. Diffusion of O2 into the blood. 2. Binding of O2 to hemoglobin. 3. Diffusion of O2 into tissue cells. 4. Transport of O2 in arterial blood. 5. Dissociation of O2 from hemoglobin.
→ 24The chemosensitive area of the brain is highly sensitive to which of the following blood parameters?
→ 25In a patient suffering from severe asthma, which of the following physiological changes is most likely to be observed?
→ 26Anatomical dead space refers to:
→ 27If a person hyperventilates excessively, blowing off large amounts of CO2, what would be the immediate effect on their blood pH?
→ 28The respiratory membrane, across which gas exchange occurs, consists of:
→ 29The Bohr effect describes the phenomenon where a decrease in pH (acidosis) or an increase in PCO2 shifts the oxyhemoglobin dissociation curve to the right. What is the physiological advantage of this effect?
→ 30The primary site of gaseous exchange in humans is the:
→ 31An athlete undergoing high-altitude training experiences a decrease in atmospheric PO2. How does the body compensate for this initial physiological challenge to maintain oxygen delivery to tissues?
→ 32Which of the following represents the maximum amount of air a person can breathe in after a forceful expiration?
→ 33Why is the chloride shift important during CO2 transport in red blood cells?
→ 34The pneumotaxic center, located in the pons, has what effect on respiration?
→ 35A person has a TV of 600 mL, IRV of 2400 mL, ERV of 900 mL, and a Residual Volume (RV) of 1100 mL. What is their Inspiratory Capacity (IC) and Expiratory Capacity (EC) respectively?
→ 36The primary respiratory rhythm-generating center in the brain is located in the:
→ 37An individual suffering from carbon monoxide poisoning will show:
→ 38During inspiration, the diaphragm:
→ 39Which of the following conditions would lead to the highest affinity of hemoglobin for oxygen?
→ 40The C-shaped cartilaginous rings are present in the wall of the trachea. What is their primary function?
→ 41A patient with emphysema experiences destruction of alveolar walls and loss of elasticity. Which of the following lung volumes or capacities would most likely increase significantly in this patient?
→ 42Peripheral chemoreceptors located in the aortic arch and carotid arteries are primarily sensitive to changes in:
→ 43During CO2 transport, carbonic anhydrase facilitates the formation of carbonic acid inside RBCs. What is the fate of this carbonic acid?
→ 44Which of the following factors would decrease the rate of diffusion of gases across the alveolar-capillary membrane?
→ 45Consider the following partial pressures: P(O2) in alveolar air = 104 mmHg P(O2) in deoxygenated blood = 40 mmHg P(CO2) in alveolar air = 40 mmHg P(CO2) in deoxygenated blood = 45 mmHg Which of the following statements correctly describes the direction of gas exchange in the alveoli?
→ 46The primary function of epiglottis during swallowing is to:
→ 47Assertion (A): The partial pressure of CO2 in the alveoli is higher than in the atmospheric air. Reason (R): Alveolar air contains CO2 contributed by the diffusion from pulmonary capillaries, which continuously occurs.
→ 48If a person's Tidal Volume (TV) is 500 mL, Inspiratory Reserve Volume (IRV) is 2500 mL, and Expiratory Reserve Volume (ERV) is 1000 mL, what is their Vital Capacity (VC)?
→ 49A shift of the oxyhemoglobin dissociation curve to the right would be caused by: 1. Increased PCO2 2. Increased pH 3. Increased temperature 4. Increased 2,3-BPG
→ 50A person is performing vigorous exercise. Which of the following changes in respiratory parameters would be most immediately observed?
→ 51If a person hyperventilates voluntarily (breathes rapidly and deeply), what would be the immediate effect on their blood gas levels and subsequent urge to breathe?
→ 52At the systemic tissues, the PCO2 gradient facilitates the diffusion of CO2:
→ 53Infant respiratory distress syndrome (IRDS) is caused by insufficient production of surfactant. This leads to:
→ 54The sigmoid shape of the oxygen dissociation curve indicates:
→ 55The pneumotaxic center, located in the pons, primarily functions to:
→ 56Anatomical dead space refers to the volume of air in the conducting airways that does not participate in gas exchange. Which of the following statements about physiological dead space is TRUE?
→ 57An increase in body temperature, such as during fever or strenuous exercise, would cause the oxygen dissociation curve to shift:
→ 58During quiet expiration, which of the following muscles are primarily involved?
→ 59A pulmonary embolism blocks blood flow to a section of the lung. This primarily leads to a mismatch between:
→ 60The respiratory membrane, across which gas exchange occurs, consists of all of the following EXCEPT:
→ 61During strenuous exercise, local tissue PO2 decreases, and PCO2 increases. How does this affect oxygen delivery to the active muscles?
→ 62To maintain electrical neutrality during the transport of bicarbonate ions out of the red blood cells into the plasma at the systemic tissues, which ion moves into the red blood cells?
→ 63A person has a Tidal Volume (TV) of 500 mL, an Inspiratory Reserve Volume (IRV) of 3000 mL, and an Expiratory Reserve Volume (ERV) of 1000 mL. If their Residual Volume (RV) is 1200 mL, what is their Functional Residual Capacity (FRC)?
→ 64The rhythmicity center for respiration, responsible for generating the basic respiratory rhythm, is located in the:
→ 65Chronic obstructive pulmonary disease (COPD) patients often develop 'blue bloater' symptoms, including cyanosis and edema. The cyanosis is primarily due to:
→ 66Which of the following structures is part of the conducting portion of the respiratory system but does not participate in gas exchange?
→ 67The Haldane effect states that the binding of oxygen to hemoglobin facilitates the unloading of CO2 from the blood. This occurs because:
→ 68The presence of surfactant in the alveoli is critical because it:
→ 69If a person's blood pH decreases significantly, what effect would this have on the oxygen dissociation curve and subsequent oxygen release to tissues?
→ 70Which of the following muscle groups is primarily responsible for expanding the thoracic cavity vertically during quiet inspiration?
→ 71In patients with pulmonary fibrosis, the thickening of the alveolar membrane significantly reduces gas exchange. This primarily affects which step of respiration?
→ 72Which of the following statements correctly describes the partial pressures of gases in normal arterial blood (systemic arteries)?
→ 73In a patient suffering from severe metabolic acidosis (e.g., uncontrolled diabetes), which of the following respiratory adjustments would be expected?
→ 74The fluid present in the pleural cavity serves to:
→ 75If the atmospheric pressure is 760 mmHg and the percentage of oxygen in the atmosphere is 21%, what is the approximate partial pressure of nitrogen (PN2) in the dry atmospheric air?
→ 76Which of the following represents the correct sequence of structures through which air passes during inspiration?
→ 77The partial pressure of oxygen (PO2) in the pulmonary artery blood is approximately 40 mmHg, while in the alveolar air it is 104 mmHg. This large gradient ensures:
→ 78Each hemoglobin molecule can maximally bind with how many oxygen molecules?
→ 79A diver experiences symptoms of nitrogen narcosis (rapture of the deep) at depth. This condition is due to:
→ 80Which of the following reflexes prevents over-inflation of the lungs?
→ 81A spirometry test reveals a patient has a significantly reduced Vital Capacity (VC) but a normal Residual Volume (RV). This pattern is most indicative of:
→ 82Which form of carbon dioxide transport in the blood accounts for the largest proportion (approximately 70%)?
→ 83The Bohr effect describes the phenomenon where a decrease in pH (or increase in PCO2) shifts the oxygen dissociation curve to the right. This physiological adaptation is crucial because it:
→ 84The C-shaped cartilaginous rings are present in the trachea to:
→ 85A person with severe asthma experiences bronchoconstriction. This primarily impacts gas exchange by:
→ 86Which of the following properties of gases makes carbon dioxide able to diffuse approximately 20-25 times faster than oxygen across the respiratory membrane, despite a smaller partial pressure gradient?
→ 87A mountaineer reaches a high altitude. Initially, their breathing rate increases. This hyperventilation primarily serves to:
→ 88The primary chemical factor regulating the rate and depth of breathing under normal physiological conditions is the concentration of:
→ 89During normal inspiration, the diaphragm contracts and flattens. Concurrently, the external intercostal muscles contract, causing the rib cage to move:
→ 90A person suffers from a condition where the respiratory membrane thickens due to fibrosis. Which of the following would be the most immediate and significant consequence?
→ 91At the systemic tissue level, oxygen diffuses from the capillaries into the tissue cells because:
→ 92Which of the following changes would primarily stimulate the central chemoreceptors in the medulla oblongata to increase respiratory rate?
→ 93A person's Forced Vital Capacity (FVC) is measured. Which of the following combinations of lung volumes correctly represents FVC?
→ 94Carbon dioxide is transported in blood primarily as bicarbonate ions. The enzyme catalyzing the reaction of CO2 and water to form carbonic acid in red blood cells is:
→ 95During forced expiration, which of the following muscles contract to increase intrathoracic pressure and expel air?
→ 96Which of the following scenarios would lead to a rightward shift of the oxygen dissociation curve (ODC)? I. Increased pH II. Increased PCO2 III. Increased temperature IV. Increased 2,3-BPG concentration
→ 97A patient presents with severe emphysema, a condition characterized by damaged alveolar walls. Which of the following would be the most significant physiological consequence affecting gas exchange?
→ 98If the partial pressure of oxygen in the inspired air is 159 mmHg, and the atmospheric pressure is 760 mmHg, what would be the approximate partial pressure of oxygen (PO2) in the alveoli, assuming typical physiological conditions and significant water vapor pressure?
→ 99A scuba diver ascending rapidly from a depth experiences 'the bends'. This condition is primarily due to:
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