Question

What is correct about human respiration? (a) About 90 per cent of \(\mathrm{CO}_{2}\) is carried by haemoglobin as carbaminohaemoglobin. (b) Neural signals from pneumotaxic centre of pons can increase the duration of inspiration. (c) Workers in grinding and stone breaking industries may suffer from lung fibrosis. (d) Cigarette smoking leads to inflammation of bronchi.

Short answer

(c) Workers in grinding and stone breaking industries may suffer from lung fibrosis and (d) Cigarette smoking leads to inflammation of bronchi are the correct statements about human respiration.

Step-by-step solution

Analyzing statement (a)

Human red blood cells carry CO2 back to the lungs where it’s exhaled. Hemoglobin can bond with carbon dioxide to produce carbaminohaemoglobin, but it only does this to about 20% of the carbon dioxide, not 90% as the statement suggests. Therefore, this statement is incorrect.

Analyzing statement (b)

The pneumotaxic center of the pons region in the brain indeed helps control breathing rates. However, neural signals from this centre would decrease the duration of inspiration, allowing a greater breathing rate. As such, this statement is incorrect.

Analyzing statement (c)

Workers in industries that deal with heavy dust like grinding and stone breaking are indeed at risk of lung-related diseases such as fibrosis. This is due to the inhalation of tiny dust particles that could cause damage to their lungs over time. Therefore, this statement is correct.

Analyzing statement (d)

Cigarette smoke contains harmful substances that damage the lining of the airways and lungs, leading to inflammation and various health problems. One such issue is the inflammation of the bronchi, also known as bronchitis. Therefore, this statement is correct.

Key concepts

Carbaminohaemoglobin

Carbaminohaemoglobin is a compound formed when carbon dioxide (\( \mathrm{CO}_2 \)) binds to hemoglobin in red blood cells. This is one of the ways \( \mathrm{CO}_2 \) is transported in the blood from tissues back to the lungs. When cells produce energy, \( \mathrm{CO}_2 \) is released as a waste product.
Most of this \( \mathrm{CO}_2 \) is carried in the blood as bicarbonate ions (approximately 70%), while about 20% is transported as carbaminohaemoglobin. The remaining \( \mathrm{CO}_2 \) is dissolved directly in the blood.

• Hemoglobin plays a dual role by also carrying oxygen from the lungs to the tissues.
• It is much more well-known for oxygen transport than for \( \mathrm{CO}_2 \) transport.

However, the binding of \( \mathrm{CO}_2 \) to hemoglobin does not significantly compete with oxygen binding, so hemoglobin can function effectively in carrying both gases.

Pneumotaxic Centre

The pneumotaxic centre is part of the respiratory system control located in the pons region of the brainstem. Its main role is to manage the timing and rhythm of breathing by regulating the transition between inhalation and exhalation.
It sends signals that inhibit inspiration so that the lungs do not overinflate.

• The pneumotaxic centre shortens the duration of each breath, thus increasing breathing frequency.
• It works alongside the apneustic centre and medullary respiratory centres to maintain a harmonious respiratory pattern.
• This balance allows respiratory adjustments based on environmental needs or body activity levels.

So, while playing a critical role in respiratory regulation, it acts to reduce the duration of inspiration rather than increasing it.

Lung Fibrosis

Lung fibrosis is a condition characterized by the formation of scar tissue within the lungs. This scar tissue makes the lungs stiffer and affects their ability to function normally. It can result from various occupational hazards or diseases, leading to chronic lung damage.
Occupations like grinding and stone-breaking expose workers to dust particles that can penetrate deep into the lungs.

• Inhalation of these particles can initiate an inflammatory response.
• Over time, continuous exposure results in the fibrotic transformation of lung tissue.
• This fibrosis reduces the lungs' capacity to expand and retract with breathing.

Symptoms can include persistent cough and breathing difficulties. Preventive measures, such as using protective equipment and reducing exposure time, are essential to mitigate the risk.

Bronchi Inflammation

Bronchi inflammation, commonly known as bronchitis, occurs when the airways in the lungs become swollen and irritated. This condition can arise from several factors, but smoking is one of the leading causes.
Cigarette smoke contains numerous irritants and toxins that affect lung health.

• These toxic substances damage the cells lining the bronchi, leading to inflammation.
• Chronic exposure to these substances can result in constant inflammation, narrowing of the airways, and increased mucus production.
• The symptoms of bronchitis include persistent cough, mucus production, and breathing difficulties.

Avoiding smoking and exposure to irritants is key to reducing the risk of bronchi inflammation and maintaining healthy lung functions.