Question

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

• A. Cigarette smoking may lead to inflammation of bronchi.
• B. Neural signals from pneumotaxic center in pons region of brain can increase the duration of inspiration.
• C. Workers in grinding and stone-breaking industries may suffer from lung fibrosis.
• D. About 90% of carbon dioxide is carried by haemoglobin as carbaminohaemoglobin.

Answer 1

The correct option is C Workers in grinding and stone-breaking industries may suffer from lung fibrosis.

Workers in industries involving grinding and stone-breaking are constantly exposed to a huge amount of dust. A long term exposure to such a huge amount of dust could result in inflammation of the fibrous tissues of the lungs, causing lung fibrosis.

Cigarette smoking most commonly results in emphysema.

The pneumatic center inhibits inspiration by controlling the "switch-off" of inspiration.

Much of the carbon dioxide in blood (70%) is transported as bicarbonate, 20-25% as carbamino-hemoglobin by the RBCs, and around 7% as dissolved in blood plasma.