N5031 GAS EXCHANGE AND
PERFUSION STUDY GUIDE UPDATED
FOR THE 2026/2027 SYLLABUS,
CONTAINING OVER 100 QUESTIONS
Unit 1: Foundations of Gas Exchange & Perfusion
1. Define gas exchange.
o ANSWER ✓ The process by which oxygen is transported from the lungs to the
bloodstream and carbon dioxide is removed from the bloodstream to the lungs.
2. Define perfusion.
o ANSWER ✓ The flow of blood through the capillary beds of tissues, delivering oxygen
and nutrients while removing waste.
3. What is the primary muscle of inspiration?
o ANSWER ✓ Diaphragm.
4. What law explains the relationship between pressure and volume in the lungs?
o ANSWER ✓ Boyle’s law.
5. What is ventilation-perfusion (V/Q) matching?
o ANSWER ✓ The alignment of alveolar ventilation and pulmonary capillary perfusion to
optimize gas exchange.
6. What is a normal V/Q ratio?
o ANSWER ✓ Approximately 0.8.
7. Define hypoxemia.
o ANSWER ✓ Low partial pressure of oxygen in arterial blood (PaO2 < 80 mm Hg).
8. Define hypoxia.
o ANSWER ✓ Insufficient oxygen at the tissue cellular level.
9. What is the difference between hypercapnia and hypocapnia?
o ANSWER ✓ Hypercapnia is elevated PaCO2 (>45 mm Hg); hypocapnia is low PaCO2
(<35 mm Hg).
10. What is the normal PaO2 range on room air?
, o ANSWER ✓ 80–100 mm Hg.
11. What is the normal SaO2 range?
o ANSWER ✓ 95–100%.
12. What is the primary drive to breathe in a healthy person?
o ANSWER ✓ Hypercapnia (increased PaCO2 acting on central chemoreceptors).
13. What is the secondary drive to breathe?
o ANSWER ✓ Hypoxemia (via peripheral chemoreceptors).
14. What are the peripheral chemoreceptors and where are they located?
o ANSWER ✓ Carotid bodies (carotid artery bifurcation) and aortic bodies (aortic arch);
sense PaO2, PaCO2, pH.
15. What is the oxyhemoglobin dissociation curve?
o ANSWER ✓ A graph showing the relationship between PaO2 and SaO2.
16. A right shift of the oxyhemoglobin dissociation curve indicates what?
o ANSWER ✓ Decreased affinity of hemoglobin for oxygen (more oxygen released to
tissues).
17. A left shift of the oxyhemoglobin dissociation curve indicates what?
o ANSWER ✓ Increased affinity of hemoglobin for oxygen (less oxygen released to
tissues).
18. Name three causes of a right shift.
o ANSWER ✓ Increased temperature, increased PaCO2 (Bohr effect), decreased pH
(acidosis). - ANSWER ✓
19. Name three causes of a left shift.
o ANSWER ✓ Decreased temperature, decreased PaCO2, increased pH (alkalosis). -
ANSWER ✓
20. What is the Bohr effect?
o ANSWER ✓ Increased CO2 and decreased pH decrease hemoglobin’s affinity for O2,
enhancing O2 release.
21. What is the Haldane effect?
o ANSWER ✓ Deoxygenated hemoglobin has a greater ability to carry CO2.
22. What is shunt?
o ANSWER ✓ Blood passes from the right to left side of the heart without participating in
gas exchange.
23. What is dead space ventilation?
o ANSWER ✓ Areas of the lung that are ventilated but not perfused.
24. Name three types of dead space.
PERFUSION STUDY GUIDE UPDATED
FOR THE 2026/2027 SYLLABUS,
CONTAINING OVER 100 QUESTIONS
Unit 1: Foundations of Gas Exchange & Perfusion
1. Define gas exchange.
o ANSWER ✓ The process by which oxygen is transported from the lungs to the
bloodstream and carbon dioxide is removed from the bloodstream to the lungs.
2. Define perfusion.
o ANSWER ✓ The flow of blood through the capillary beds of tissues, delivering oxygen
and nutrients while removing waste.
3. What is the primary muscle of inspiration?
o ANSWER ✓ Diaphragm.
4. What law explains the relationship between pressure and volume in the lungs?
o ANSWER ✓ Boyle’s law.
5. What is ventilation-perfusion (V/Q) matching?
o ANSWER ✓ The alignment of alveolar ventilation and pulmonary capillary perfusion to
optimize gas exchange.
6. What is a normal V/Q ratio?
o ANSWER ✓ Approximately 0.8.
7. Define hypoxemia.
o ANSWER ✓ Low partial pressure of oxygen in arterial blood (PaO2 < 80 mm Hg).
8. Define hypoxia.
o ANSWER ✓ Insufficient oxygen at the tissue cellular level.
9. What is the difference between hypercapnia and hypocapnia?
o ANSWER ✓ Hypercapnia is elevated PaCO2 (>45 mm Hg); hypocapnia is low PaCO2
(<35 mm Hg).
10. What is the normal PaO2 range on room air?
, o ANSWER ✓ 80–100 mm Hg.
11. What is the normal SaO2 range?
o ANSWER ✓ 95–100%.
12. What is the primary drive to breathe in a healthy person?
o ANSWER ✓ Hypercapnia (increased PaCO2 acting on central chemoreceptors).
13. What is the secondary drive to breathe?
o ANSWER ✓ Hypoxemia (via peripheral chemoreceptors).
14. What are the peripheral chemoreceptors and where are they located?
o ANSWER ✓ Carotid bodies (carotid artery bifurcation) and aortic bodies (aortic arch);
sense PaO2, PaCO2, pH.
15. What is the oxyhemoglobin dissociation curve?
o ANSWER ✓ A graph showing the relationship between PaO2 and SaO2.
16. A right shift of the oxyhemoglobin dissociation curve indicates what?
o ANSWER ✓ Decreased affinity of hemoglobin for oxygen (more oxygen released to
tissues).
17. A left shift of the oxyhemoglobin dissociation curve indicates what?
o ANSWER ✓ Increased affinity of hemoglobin for oxygen (less oxygen released to
tissues).
18. Name three causes of a right shift.
o ANSWER ✓ Increased temperature, increased PaCO2 (Bohr effect), decreased pH
(acidosis). - ANSWER ✓
19. Name three causes of a left shift.
o ANSWER ✓ Decreased temperature, decreased PaCO2, increased pH (alkalosis). -
ANSWER ✓
20. What is the Bohr effect?
o ANSWER ✓ Increased CO2 and decreased pH decrease hemoglobin’s affinity for O2,
enhancing O2 release.
21. What is the Haldane effect?
o ANSWER ✓ Deoxygenated hemoglobin has a greater ability to carry CO2.
22. What is shunt?
o ANSWER ✓ Blood passes from the right to left side of the heart without participating in
gas exchange.
23. What is dead space ventilation?
o ANSWER ✓ Areas of the lung that are ventilated but not perfused.
24. Name three types of dead space.
