Name the pulmonary disease in which alveolar surface area involved in gas exchange is drastically reduced due to damage in the alveolar walls.

When you hold your breath, which of the following gas changes in blood would first lead to the urge to breathe?
1. Falling O₂ concentration
2. Rising CO₂ concentration
3. Falling CO₂ concentration
4. Rising CO₂ and falling O₂ concentration

Approximately seventy percent of carbon dioxide absorbed by the blood will be transported to the lungs:

The figure shows a diagrammatic view of the human respiratory system with labels A, B, C, and D. Select the option that gives the correct identification, main function, and/or characteristics:

Which one of the following is the correct statement for respiration in humans?

The figure given below shows a small part of the human lung where exchange of gases takes place. In which one of the options given below, the one part A, B, C or D is correctly identified along with its function?

   

1.	A – Alveolar cavity – main site of exchange of respiratory gases
2.	D – Capillary wall – exchange of O2 and CO2 takes place here
3.	B – Red blood cell –  transport of CO2 mainly.
4.	C – Arterial capillary – passes oxygen to tissues

A large proportion of oxygen is left unused in the human blood even after its uptake by body tissues. This O₂:

1. raises the P_co2 blood to 75 mm of Hg

2. is enough to keep oxyhaemoglobin

3. helps in releasing more O₂ to the epithelial tissues

4. acts as a reserve during muscular exercise

Bulk of carbon dioxide (CO₂) released from body tissues into the blood is present as:
1. carbaminohaemoglobin in RBCs
2. bicarbonate in blood plasma and RBCs
3. free CO₂ in blood plasma
4. 70% carbaminohaemoglobin and 30% as bicarbonate

Which one of the following is a possibility for most of us in regard to breathing, by making a conscious effort?