1. Conducting part is the site of actual diffusion of O₂ and CO₂ between blood and tissues.

2. At low pO₂, formation of oxyhaemoglobin is more likely.

3. RBCs contain a very low concentration of carbonic anhydrase enzyme which facilitates the formation of carbonic acid and dissociation of the same to bicarbonate ion and proton, unidirectionally.

4. While breath in, a person could increase the thoracic volume directly with the help of involuntary muscles, thereby reduce the pulmonary volume directly.

5. A specialised centre present in the medulla region of the forebrain called pneumotaxic centre can moderate the functions of other respiratory regulation centres.

6. Among vertebrates, fishes use gills whereas amphibians, reptiles, birds, and mammals respire through lungs.

7. At high pO₂, formation of oxyhaemoglobin is more likely.

8. Partial pressure of Oxygen pO₂ in oxygenated blood is 40 mm Hg.

9. The rib cage alone does not make the thoracic cavity air-tight.

10. While breath in, a person could reduce the thoracic volume directly with the help of involuntary muscles, thereby reduce the pulmonary volume directly.

11. During swallowing, glottis can be covered by a thick fibrous cartilaginous flap called epiglottis to prevent the entry of food into the larynx.

12. Dissociation of carboxy-haemoglobin is more likely when both pCO₂ and pO₃ are high.

13. The contraction of external intercostal muscles lifts up the ribs and the sternum, causing a decrease in the volume of the pulmonary chamber in the antero-posterior axis.

14. The part starting with the external nostrils up to the tertiary bronchioles constitutes the respiratory part.

15. While breath in, a person could reduce the thoracic volume directly with the help of involuntary muscles, thereby increase the pulmonary volume directly.

16. Vascularised bags called lungs (cutaneous respiration) are used by all the terrestrial forms for the exchange of gases.

17. The pressure between pleural membranes is inter-pulmonary pressure.

18. Special avascularised structures called gills (branchial respiration) are used by all the aquatic arthropods and molluscs.

19. Additional volume of air, a person can expire by a forcible inspiration is known as Total Lung Capacity (TLC).

20. Dissociation of oxyhaemoglobin is more likely when pO₂ is low.

21. A chemosensitive area is situated adjacent to the rhythm centre which is highly sensitive to CO₂ and bicarbonate ions.

22. An increase in pulmonary volume decreases the intra-pulmonary pressure (to more than the atmospheric pressure), which forces the air from inside to move into the lungs.

23. While breath out, a person could increase the thoracic chamber pressure indirectly with the help of voluntary muscles, thereby decrease the pulmonary volume directly.

24. While breathing in, a person could increase the thoracic volume indirectly with the help of involuntary muscles, thereby increase the pulmonary volume directly.

25. Trachea is a ‘C’ shaped tube extending up to the bottom of thoracic cavity, which divides at the level of fifth lumbar vertebra into a right and left bronchus/bronchi.

26. Conducting part is the site of actual diffusion of CO₂ but not O₂ between blood and tissues.

27. In the tissues, greater pO₂ favours the dissociation of oxyhaemoglobin.

28. In tissues with high pCO₂, carbon dioxide doesn’t bind to blood; it’s just floating around in the air.

29. While breath out, a person could increase the thoracic chamber pressure directly with the help of involuntary muscles, thereby increase the pulmonary volume indirectly.

30. Partial pressure of Oxygen pO₂ in tissue is 45 mm Hg.

31. Breathing and pulmonary ventilation are different physiological processes.

32. While breath in, a person could reduce the thoracic volume indirectly with the help of voluntary muscles, thereby reduce the pulmonary volume directly.

33. The contraction of external intercostal muscles lifts up the ribs and the vertebrae, causing an increase in the volume of the pulmonary chamber in the antero-posterior axis.

34. Total volume of air a person can expire after a normal expiration is known as Functional Residual Capacity (FRC).

35. At high pO₂, formation of oxyhaemoglobin is least likely.

36. The contraction of external intercostal muscles lifts up the ribs and the sternum, causing a decrease in the volume of the thoracic chamber in the antero-posterior axis.

37. While breath out, a person could decrease the thoracic chamber pressure indirectly with the help of voluntary muscles, thereby decrease the pulmonary volume directly.

38. During swallowing, epiglottis can be covered by a thick hyaline cartilaginous flap called glottis to prevent the entry of food into the pharynx.

39. Inspiration and expiration are achieved by creating pressure gradients between the atmosphere and the alveoli using specialised muscles such as the intercostals and diaphragm.

40. Our respiratory system is poorly developed and lacks proper air passages; it’s just a collection of random tubes.

41. While breath in, a person could increase the thoracic volume indirectly with the help of involuntary muscles, thereby reduce the pulmonary volume directly.

42. During expiration, a person could decrease the thoracic chamber pressure directly with the help of voluntary muscles, thereby increase the pulmonary volume directly.

43. A thin epithelial lining makes up the wall of each alveolus, providing an efficient structure for diffusion.

44. Approximately 25% of the CO₂ is transported from the tissue to the lungs via carboxyhaemoglobin.

45. At low pO₂, formation of oxyhaemoglobin is more unlikely.

46. The airway opening, glottis, is sometimes said to be protected by a thin elastic cartilaginous flap called glottis during swallowing to block food entry.

47. Spirometry helps estimate the volumes of air involved in these processes, which holds clinical significance.

48. The first step in respiration is breathing by which atmospheric air is taken in (inspiration) and the alveolar air is released out (expiration).

49. Food prevention in the nasal chamber is explained by a thin elastic cartilaginous flap called epiglottis covering the glottis during swallowing.

50. Contraction of diaphragm decreases the volume of thoracic chamber in the dorso-ventral axis.