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

Lungs are made up of air-filled sacs, the alveoli. They do not collapse even after forceful expiration, because of

1. Residual Volume (RV)

2. Inspiratory Reserve Volume (IRV)

3. Tidal Volume (TV)

4. Expiratory Reserve Volume (ERV)

The partial pressure of oxygen in the alveoli of the lungs is  

(1) equal to that in the blood

(2) more than that in the blood

(3) less than that in the blood

(4) less than that of carbon dioxide

Lungs do not collapse between breaths and some air always remains in the lungs which can never be expelled because

(1) there is a negative pressure in the lungs

(2) there is a negative intrapleural pressure pulling at the lung walls

(3) there is a positive intrapleural pressure

(4) pressure in the lungs in higher than the atmospheric pressure

Reduction in pH of blood will

(1) reduce the blood supply to the brain

(2) decrease the affinity of hemoglobin with oxygen

(3) release bicarbonate ions by the liver

(4) reduce the rate of heart beat

Name the chronic respiratory disorder caused mainly by cigarette smoking

1. asthma

2. respiratofy acidosis

3. respiratory alkalosis

4. emphysema

Approximately seventy percent of carbon dioxide absorbed by the blood will be

transported to the lungs

1. as bicarbonate ions

2. in the form of dissolved gas molecules

3. by binding to RBC

4. as carbamino-haemoglobin

The figure shows a diagrammatic view of human respiratory system with labels A, B, C

and D. Select the option, which gives correct identification and main function and/or

characteristic.

1. A-trachea-long tube supported by complete cartilaginous rings for conducting

inspired air

2. 8-pleural membrane-surround ribs on both sides to provide cushion against rubbing

3. C-alveoli-thin walled vascular bag-like structures for exchange of gases

4. D-lower end of lungs-diaphragm pulls it down during inspiration

People who have migrated from the planes to an area adjoining Rohtang Pass about six

months back

1. have more RBCs and their haemoglobin has a lower binding affinity to O₂

2. are not physically fit to play games like football

3. suffer from altitude sickness with symptoms like nausea, fatigue, etc.

4. have the usual RBC count but their haemoglobin has very high binding affinuty to O₂

A large proportion of oxygen is left unsused in the human blood even after its uptake by

the body tissues. This O₂

1. raises the P_CO2 of blood to 75 mm of Hg

2. is enough to keep oxyhaemoglobin

3. helps in relasing more O₂ to the epithelial tissues

4. acts as a reserve during muscular exercise