Select the correct events that occur during
inspiration.
A. Contraction of diaphragm
B. Contraction of external inter-costal muscles
C. Pulmonary volume decreases
D. Intra pulmonary pressure increases
AI-generated explanation. Check against your textbook.
Explanation:
During inspiration, the diaphragm contracts and flattens, and the external intercostal muscles contract to raise the ribs. This enlarges the thoracic cavity, increasing pulmonary (lung) volume. As a result, intra-pulmonary pressure falls below atmospheric pressure, allowing air to flow into the lungs. Therefore, A and B are correct, while C (volume decreases) and D (pressure increases) are incorrect.
🧠 Did You Know?
Inhalation involves active muscular work; exhalation at rest is mainly a passive process where the diaphragm and intercostals relax, pushing air out as the chest cavity returns to its smaller volume.
💡 NCERT Memory Line:
During inspiration, rib cage moves up and out; diaphragm contracts to increase thoracic volume, causing a decrease in intra-pulmonary pressure.
According to Central Pollution Control Board [CPCB]
what size (in diameter) of particulate is responsible for causing greater harm to human health ?
AI-generated explanation. Check against your textbook.
Explanation:
PM2.5 (particulate matter with diameter 2.5 μm or less) is most harmful because it can penetrate deep into the lungs and even enter the bloodstream. According to CPCB guidelines, these tiny particles cause greater health effects than larger particles. Thus, option 2 (2.5 micrometers) is correct. Larger particles like 3.0–4.0 μm (options 1, 3, 4) are more likely to lodge in the nose or throat and are less able to reach deep lung tissues, causing comparatively milder effects.
🧠 Did You Know?
NCERT explains that finer particles, especially PM2.5, pose serious health risks, including respiratory and cardiovascular problems.
💡 NCERT Memory Line:
PM2.5 refers to particulates with diameter 2.5 μm or less, capable of reaching deep lungs and entering the bloodstream, causing greater health impacts.
The increase in osmolarity from outer to inner medullary interstitium is maintained due to:
I. Close proximity between Henle's loop and vasa recta
II. Counter current mechanism
III. Selective secretion of HCO3- and hydrogen ions in PCT
IV. Higher blood pressure in glomerular capillaries