Respiratory adaptations Practice Questions
20 free Respiratory adaptations practice questions for the Physiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
The primary immediate respiratory adaptation to high altitude is:
- A Increased red blood cell count
- B Increased ventilation
- C Increased hemoglobin affinity for oxygen
- D Increased lung surface area
Correct answer: Increased ventilation
Hypoxia at high altitude stimulates peripheral chemoreceptors, increasing ventilation. This helps raise alveolar oxygen partial pressure.
Long-term residence at high altitude leads to increased oxygen-carrying capacity mainly due to:
- A Increased plasma volume
- B Increased erythropoietin secretion
- C Reduced hemoglobin breakdown
- D Increased alveolar ventilation only
Correct answer: Increased erythropoietin secretion
Chronic hypoxia stimulates erythropoietin release from the kidneys. This increases red blood cell production and hemoglobin concentration.
During acclimatization to high altitude, the oxygen–hemoglobin dissociation curve shifts:
- A To the left due to respiratory alkalosis
- B To the right due to increased 2,3-BPG
- C Downward due to reduced hemoglobin
- D Upward due to increased carbon dioxide
Correct answer: To the right due to increased 2,3-BPG
Increased 2,3-BPG levels shift the curve to the right. This facilitates oxygen unloading to tissues.
Which respiratory adaptation improves oxygen diffusion at high altitude?
- A Progressive thickening of the alveolar membrane
- B Increased alveolar-capillary surface area
- C Chronically reduced pulmonary blood flow
- D A persistently decreased ventilation-perfusion ratio
Correct answer: Increased alveolar-capillary surface area
Chronic exposure increases capillary density and effective surface area. This enhances oxygen diffusion across the alveoli.
The initial cause of respiratory alkalosis at high altitude is:
- A Renal bicarbonate loss
- B Hypoventilation
- C Hyperventilation
- D Increased lactic acid production
Correct answer: Hyperventilation
Hyperventilation reduces arterial carbon dioxide levels. This leads to respiratory alkalosis early in high-altitude exposure.
Renal compensation for respiratory alkalosis during altitude acclimatization involves:
- A Increased bicarbonate reabsorption
- B Increased hydrogen ion secretion
- C Increased bicarbonate excretion
- D Decreased urine output
Correct answer: Increased bicarbonate excretion
The kidneys excrete bicarbonate to correct alkalosis. This allows ventilation to remain elevated.
During exercise training, increased ventilation is primarily due to:
- A Reduced lung compliance
- B Increased central neural drive
- C Decreased oxygen consumption
- D Reduced carbon dioxide production
Correct answer: Increased central neural drive
Exercise increases central neural input to respiratory centers. This raises ventilation even before blood gas changes occur.
Which adaptation improves oxygen uptake during endurance training?
- A Chronically reduced alveolar ventilation at rest
- B Increased capillary density in lungs
- C A decrease in circulating hemoglobin concentration
- D Increased resistance across the conducting airways
Correct answer: Increased capillary density in lungs
Increased pulmonary capillary density enhances gas exchange efficiency. This supports higher oxygen uptake during exercise.
The primary respiratory adaptation to chronic exercise is an increase in:
- A Resting respiratory rate
- B Ventilatory efficiency
- C Anatomical dead space
- D Airway resistance
Correct answer: Ventilatory efficiency
Training improves ventilatory efficiency by better matching ventilation to perfusion. Resting respiratory rate usually remains unchanged.
High-altitude natives often have which respiratory characteristic?
- A Lower lung volumes
- B Higher hemoglobin affinity for oxygen
- C Larger lung volumes
- D Reduced ventilation
Correct answer: Larger lung volumes
High-altitude natives typically develop larger lung volumes. This increases alveolar ventilation and oxygen uptake.
Which adaptation reduces diffusion limitation during exercise?
- A A generalized reduction in pulmonary blood flow
- B Increased pulmonary capillary recruitment
- C Increased thickness of the alveolar membrane
- D A sustained decrease in overall ventilation
Correct answer: Increased pulmonary capillary recruitment
Exercise recruits additional pulmonary capillaries. This improves diffusion capacity for oxygen.
During acute exposure to high altitude, arterial oxygen saturation initially:
- A Increases
- B Remains unchanged
- C Decreases
- D Exceeds sea-level values
Correct answer: Decreases
Reduced barometric pressure lowers inspired oxygen partial pressure. This decreases arterial oxygen saturation.
Which factor primarily limits maximal ventilation during intense exercise?
- A Airway resistance
- B Respiratory muscle strength
- C Pulmonary diffusion capacity
- D Hemoglobin concentration
Correct answer: Respiratory muscle strength
Respiratory muscle performance can limit maximal ventilation. Training can improve this capacity.
An increase in tidal volume during exercise helps by:
- A Increasing dead space ventilation
- B Reducing alveolar ventilation
- C Improving alveolar ventilation
- D Reducing oxygen consumption
Correct answer: Improving alveolar ventilation
Larger tidal volumes reduce the proportion of dead space ventilation. This improves effective alveolar ventilation.
Which respiratory adaptation is most important for sustaining prolonged exercise?
- A Increased resting ventilation at rest
- B Improved gas exchange efficiency
- C Reduced lung compliance
- D Progressively increased airway resistance
Correct answer: Improved gas exchange efficiency
Efficient gas exchange ensures adequate oxygen delivery during prolonged activity. This adaptation supports endurance performance.
At high altitude, pulmonary arterial pressure may increase due to:
- A Systemic vasodilation
- B Hypoxic pulmonary vasoconstriction
- C Reduced blood viscosity
- D Increased alveolar oxygen pressure
Correct answer: Hypoxic pulmonary vasoconstriction
Hypoxia causes pulmonary vasoconstriction. This raises pulmonary arterial pressure at high altitude.
Which adaptation helps prevent excessive respiratory alkalosis during chronic altitude exposure?
- A Decreased ventilation
- B Renal bicarbonate excretion
- C Increased carbon dioxide production
- D Reduced hemoglobin concentration
Correct answer: Renal bicarbonate excretion
Renal loss of bicarbonate compensates for alkalosis. This stabilizes blood pH while ventilation remains high.
Endurance training affects breathing during submaximal exercise by:
- A Increasing ventilation at the same workload
- B Decreasing ventilation at the same workload
- C Increasing respiratory rate only
- D Reducing tidal volume
Correct answer: Decreasing ventilation at the same workload
Training reduces ventilation required for a given workload. This reflects improved metabolic efficiency.
Which adaptation enhances oxygen unloading in tissues during exercise?
- A Leftward shift of the oxygen dissociation curve
- B Rightward shift of the oxygen dissociation curve
- C Reduced core body temperature during sustained activity
- D Decreased red cell 2,3-BPG concentration
Correct answer: Rightward shift of the oxygen dissociation curve
Exercising muscle is warm and acidic, produces carbon dioxide, and raises red cell 2,3-BPG. Each of these lowers haemoglobin's oxygen affinity and shifts the dissociation curve to the right, so haemoglobin gives up more oxygen at any given tissue partial pressure. A leftward shift, cooling, or falling 2,3-BPG would all tighten oxygen binding and impair unloading.
The most important respiratory adaptation that improves survival at high altitude is:
- A Increased lung compliance
- B Increased ventilation
- C Decreased oxygen consumption
- D Reduced pulmonary blood flow
Correct answer: Increased ventilation
Increased ventilation is the earliest and most critical response to hypoxia. It raises alveolar and arterial oxygen levels.