People living at sea level have around 5 million RBC per cubic millimeter of their blood whereas those living at an altitude of 5400 metres have around 8 million. This is because at high altitude:
1. people get pollution-free air to breathe and more oxygen is available
2. atmospheric O2 level is less and hence more RBCs are needed to absorb the required amount of O2 to survive
3. there is more UV radiation which enhances RBC production
4. people eat more nutritive food, therefore more RBCs are formed

Subtopic:  Respiratory System: Exchange of Gases |
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The majority of carbon dioxide produced by our body cells is transported to the lungs:
1. dissolved in the blood
2. as bicarbonates
3. as carbonates
4. attached to haemoglobin

Subtopic:  Respiratory System: Transport of Gases |
 92%
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Consider the following statements:

I: The diffusing capacity of CO2 across the respiratory membrane is higher than that of O2
II: The presence of Hb increases the efficiency of O2 transport by about 10 times.
III: Carbon monoxide binds to Hb with much more tenacity with respect to O2

Which of the above statements are true?

1. I and II only            2. I and III only
3. II and III only          4. I, II, and III
Subtopic:  Respiratory System: Exchange of Gases |
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Name the pulmonary disease in which alveolar surface area involved in gas exchange is drastically reduced due to damage in the alveolar walls.
1. Pleurisy
2. Pneumonia
3. Emphysema
4. Asthma

Subtopic:  Respiratory Disorders: Part 1 |
 89%
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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. B-pleural membrane-surrounds 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

Subtopic:  Respiratory System: Trachea & Basic Anatomy of Lung |
 81%
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Which one of the following statements is incorrect?
1. The residual air in lungs slightly decreases the efficiency of respiration in mammals
2. The presence of non-respiratory air sacs increases the efficiency of respiration in birds
3. In insects, circulating body fluids serve to distribute oxygen to tissues
4. The principle of counter current flow facilitates efficient respiration in gills of fishes

Subtopic:  Respiratory System: Exchange of Gases |

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Which of the following match is correct?
1. Emphysema : reduction of surface area of alveoli and bronchi
2. Pneumonia : occupational disease with asbestos
3. Silicosis : inflammation of alveoli
4. Asthma : excessive secretion of bronchial mucus

Subtopic:  Respiratory Disorders: Part 2 |
 71%
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When a man inhales air containing normal concentration of O2 as well as CO he suffers from suffocation because
1. CO reacts with O2, reducing its percentage in air
2. haemoglobin combines with CO instead of O2 and forms carboxyhaemoglobin
3. CO affects diaphragm and intercostal muscles
4. CO affects the nerves of the lungs

Subtopic:  Respiratory System: Exchange of Gases |
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Respiration is controlled by
1. medulla oblongata
2. cerebellum
3. hypothalamus
4. cerebrum

Subtopic:  Respiratory System: Regulation of Respiration |
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Chemosensitive area of respiratory centre medulla is affected by
1. less CO2 and H+ ions
2. less O2 and H+ ions
3. excess CO2 and H+ ions
4. excess O2 and H+ ions.

Subtopic:  Respiratory System: Regulation of Respiration |
 85%
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