Breathing and Exchange of Gases · Question 27

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 is higher than the atmospheric pressure.

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

1. Pneumonia
2. Asthma
3. Pleurisy
4. Emphysema

When you hold your breath, which of the following gas changes in blood would first lead to the urge to breathe?

1. Falling CO2 concentration
2. Rising CO2 and falling O2 concentration
3. Falling O2 concentration
4. Rising CO2 concentration

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 R.B.C.
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. [Figure]

1. A - Trachea - Long tube supported by complete cartilaginous rings for conducting inspired air.
2. C - Alveoli - Thin walled vascular bag like structures for exchange of gases.
3. B - Pleural membrane - Surround ribs on both sides to provide cushion against rubbing.
4. D - Lower end of lungs - Diaphragm pulls it down during inspiration.

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

1. Cigarette smoking may lead to inflammation of bronchi.
2. Neural signals from pneumotaxic centre in pons region of brain can increase the duration of inspiration.
3. Workers in grinding and stone-breaking industries may suffer from lung fibrosis.
4. About 90% of carbon dioxide (CO2) is carried by haemoglobin as carbamino-haemoglobin.

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

1. One can breathe out air totally without oxygen.
2. One can breathe out air through Eustachian tube by closing both nose and mouth.
3. One can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all.
4. The lungs can be made fully empty by forcefully breathing out all air from them.

Bulk of carbon dioxide (CO2) released from body tissues into the blood is present as

1. bicarbonate in blood plasma and RBCs
2. free CO2 in blood plasma
3. 70% carbamino-haemoglobin and 30% as bicarbonate
4. carbamino-haemoglobin in RBCs.

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

1. acts as a reserve during muscular exercise
2. raises the pCO2 of blood to 75 mm of Hg.
3. is enough to keep oxyhaemoglobin saturation at 96%
4. helps in releasing more O2 to the epithelial tissues.