Hypoxia and hypercapnia Practice Questions
29 free Hypoxia and hypercapnia practice questions for the Physiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Hypoxia is best defined as:
- A Decreased arterial carbon dioxide tension
- B Inadequate oxygen supply to tissues
- C Reduced ventilation of the lungs
- D Abnormally high blood oxygen content
Correct answer: Inadequate oxygen supply to tissues
Hypoxia refers to insufficient oxygen availability at the tissue level. It can occur despite normal oxygen content in the blood.
Which type of hypoxia occurs due to reduced arterial oxygen tension?
- A Anemic hypoxia
- B Hypoxic hypoxia
- C Stagnant hypoxia
- D Histotoxic hypoxia
Correct answer: Hypoxic hypoxia
Hypoxic hypoxia results from low arterial oxygen pressure. It is commonly seen at high altitude or in lung diseases.
Anemic hypoxia is primarily caused by:
- A Reduced hemoglobin concentration
- B Reduced cardiac output and perfusion
- C Impaired cellular oxygen utilization
- D Reduced alveolar ventilation rate
Correct answer: Reduced hemoglobin concentration
Anemic hypoxia occurs when hemoglobin concentration is low. Oxygen tension may be normal, but oxygen-carrying capacity is reduced.
Stagnant hypoxia is most commonly associated with:
- A Carbon monoxide poisoning
- B Severe anemia
- C Heart failure
- D High altitude exposure
Correct answer: Heart failure
Stagnant hypoxia occurs due to reduced blood flow. Heart failure decreases tissue perfusion leading to hypoxia.
Histotoxic hypoxia is characterized by:
- A Reduced oxygen delivery to tissues
- B Impaired oxygen use by tissues
- C Low circulating hemoglobin levels
- D Decreased arterial oxygen tension overall
Correct answer: Impaired oxygen use by tissues
In histotoxic hypoxia, tissues cannot utilize oxygen despite adequate delivery. Cyanide poisoning is a classic cause.
Which condition produces hypoxia with normal arterial oxygen tension?
- A High altitude exposure
- B Anemia
- C Chronic lung disease
- D Hypoventilation
Correct answer: Anemia
In anemia, arterial oxygen tension remains normal. Hypoxia results from reduced oxygen-carrying capacity.
The primary stimulus for ventilation during hypercapnia is:
- A Decreased arterial oxygen
- B Increased hydrogen ion concentration
- C Decreased pH in cerebrospinal fluid
- D Increased bicarbonate levels
Correct answer: Decreased pH in cerebrospinal fluid
Carbon dioxide diffuses into the CSF and forms hydrogen ions. This stimulates central chemoreceptors to increase ventilation.
Hypercapnia refers to:
- A Decreased oxygen in blood
- B Increased carbon dioxide in blood
- C Decreased carbon dioxide in blood
- D Increased oxygen saturation
Correct answer: Increased carbon dioxide in blood
Hypercapnia is an elevation of arterial carbon dioxide tension. It commonly results from hypoventilation.
Which hypoxia type is most effectively corrected by oxygen therapy?
- A Histotoxic hypoxia
- B Anemic hypoxia
- C Stagnant hypoxia
- D Hypoxic hypoxia
Correct answer: Hypoxic hypoxia
Hypoxic hypoxia responds well to oxygen supplementation. Increasing inspired oxygen raises arterial oxygen tension.
Cyanosis is most likely to be observed in:
- A Anemic hypoxia
- B Histotoxic hypoxia
- C Hypoxic hypoxia
- D Mild hypercapnia
Correct answer: Hypoxic hypoxia
Cyanosis occurs when deoxygenated hemoglobin exceeds a threshold level. This is common in hypoxic hypoxia.
Which receptor primarily detects hypercapnia?
- A Peripheral chemoreceptors
- B Central chemoreceptors
- C Baroreceptors
- D Pulmonary stretch receptors
Correct answer: Central chemoreceptors
Central chemoreceptors in the medulla respond to changes in CO2 via CSF pH. They are the main detectors of hypercapnia.
Peripheral chemoreceptors are most sensitive to changes in:
- A Carbon dioxide
- B Oxygen tension
- C Blood pressure
- D Blood glucose
Correct answer: Oxygen tension
Peripheral chemoreceptors respond strongly to decreased arterial oxygen tension. They are located in carotid and aortic bodies.
Carbon monoxide poisoning causes hypoxia by:
- A Reducing alveolar ventilation rate
- B Directly blocking oxygen diffusion
- C Reducing hemoglobin availability
- D Increasing tissue oxygen demand markedly
Correct answer: Reducing hemoglobin availability
Carbon monoxide binds hemoglobin with high affinity. This reduces oxygen transport capacity and causes anemic hypoxia.
Which condition produces both hypoxia and hypercapnia?
- A High altitude exposure
- B Severe hypoventilation
- C Anemia
- D Carbon monoxide poisoning
Correct answer: Severe hypoventilation
Hypoventilation reduces oxygen intake and carbon dioxide removal. This results in both hypoxia and hypercapnia.
Hypercapnia leads to which acid–base disturbance?
- A Metabolic alkalosis
- B Respiratory alkalosis
- C Metabolic acidosis
- D Respiratory acidosis
Correct answer: Respiratory acidosis
Elevated CO2 increases carbonic acid formation. This leads to respiratory acidosis.
Which hypoxia type shows increased venous oxygen content?
- A Anemic hypoxia
- B Hypoxic hypoxia
- C Stagnant hypoxia
- D Histotoxic hypoxia
Correct answer: Histotoxic hypoxia
In histotoxic hypoxia, tissues cannot use oxygen. As a result, venous blood remains oxygen-rich.
In chronic hypercapnia, renal compensation occurs by:
- A Excreting bicarbonate
- B Retaining bicarbonate
- C Reducing hydrogen ion secretion
- D Reducing sodium reabsorption
Correct answer: Retaining bicarbonate
The kidneys retain bicarbonate to buffer excess acid. This helps compensate for chronic respiratory acidosis.
Which symptom is commonly associated with acute hypoxia?
- A Bradycardia
- B Mental confusion
- C Hypothermia
- D Decreased respiratory rate
Correct answer: Mental confusion
The brain is highly sensitive to oxygen deprivation. Acute hypoxia often causes confusion and restlessness.
Which hypoxia type is most dangerous despite normal oxygen delivery?
- A Anemic hypoxia
- B Stagnant hypoxia
- C Histotoxic hypoxia
- D Hypoxic hypoxia
Correct answer: Histotoxic hypoxia
Histotoxic hypoxia prevents cellular oxygen utilization. This leads to rapid cellular failure despite normal oxygen supply.
Which change occurs in hypercapnia-induced ventilation?
- A Decreased tidal volume
- B Decreased respiratory rate
- C Increased alveolar ventilation
- D Reduced chemoreceptor sensitivity
Correct answer: Increased alveolar ventilation
Hypercapnia stimulates ventilation through central chemoreceptors. This increases alveolar ventilation to remove CO2.
Which type of hypoxia is characterized by normal arterial oxygen tension but reduced oxygen-carrying capacity?
- A Anemic hypoxia
- B Hypoxic hypoxia
- C Stagnant hypoxia
- D Histotoxic hypoxia
Correct answer: Anemic hypoxia
Anemic hypoxia occurs when hemoglobin levels or function are reduced, limiting oxygen transport despite normal arterial oxygen tension.
Which hypoxia type is most effectively corrected by administration of supplemental oxygen?
- A Anemic hypoxia
- B Histotoxic hypoxia
- C Hypoxic hypoxia
- D Stagnant hypoxia
Correct answer: Hypoxic hypoxia
Hypoxic hypoxia results from low arterial oxygen tension and is best corrected by increasing inspired oxygen concentration.
Which condition commonly produces both hypoxia and hypercapnia?
- A Pulmonary hypoventilation
- B High altitude exposure during exercise
- C Severe iron-deficiency anemia
- D Acute cyanide poisoning
Correct answer: Pulmonary hypoventilation
Hypoventilation reduces oxygen intake and carbon dioxide elimination, leading to both hypoxia and hypercapnia.
Hypercapnia leads to which acid-base disturbance?
- A Metabolic alkalosis
- B Metabolic acidosis
- C Respiratory acidosis
- D Respiratory alkalosis
Correct answer: Respiratory acidosis
Hypercapnia increases CO2 levels, forming carbonic acid and lowering pH, resulting in respiratory acidosis.
What is the primary ventilatory response to hypercapnia?
- A Decreased breathing rate
- B Increased ventilation
- C No change in breathing
- D Apnea
Correct answer: Increased ventilation
Elevated CO2 strongly stimulates ventilation via central chemoreceptors, increasing respiratory rate and depth.
Which type of hypoxia results from reduced arterial oxygen tension?
- A Anemic hypoxia
- B Hypoxic hypoxia
- C Histotoxic hypoxia
- D Stagnant hypoxia
Correct answer: Hypoxic hypoxia
Hypoxic hypoxia occurs when arterial oxygen tension is reduced, such as in high altitude or lung disease.
In chronic hypercapnia, renal compensation involves:
- A Decreased bicarbonate reabsorption
- B Increased bicarbonate retention
- C Increased hydrogen ion retention
- D Reduced ventilation
Correct answer: Increased bicarbonate retention
The kidneys compensate for chronic hypercapnia by increasing bicarbonate reabsorption to buffer excess acid.
Which type of hypoxia is most dangerous despite normal oxygen delivery?
- A Hypoxic hypoxia
- B Anemic (hypemic) hypoxia
- C Histotoxic hypoxia
- D Stagnant hypoxia
Correct answer: Histotoxic hypoxia
Histotoxic hypoxia prevents cells from using oxygen, making it dangerous even when oxygen delivery is adequate.
Which receptors primarily detect changes in carbon dioxide levels?
- A Peripheral chemoreceptors
- B Central chemoreceptors
- C Baroreceptors
- D Mechanoreceptors
Correct answer: Central chemoreceptors
Central chemoreceptors are highly sensitive to CO2 and pH changes in cerebrospinal fluid, regulating ventilation.