Final answer:
Water damages the lungs due to surface tension, making it difficult to inhale. Amniotic fluid, on the other hand, doesn't damage the lungs because it contains surfactant, which reduces surface tension and allows proper lung inflation.
Step-by-step explanation:
When water enters the lungs, the surface tension is too great, making it difficult to inhale. This is a serious issue for drowning victims and causes difficulty in inflating the lungs of newborn infants. In contrast, amniotic fluid doesn't damage the lungs because it contains surfactant, a substance that reduces surface tension and allows the lungs to inflate properly. The surfactant in amniotic fluid is essential for the development of the lungs in the fetus. The lungs are sensitive organs, and their interaction with various fluids is governed by delicate biological mechanisms. During gestation, the fetus 'practices' breathing by inhaling amniotic fluid, which helps in the development of the lungs. This fluid is essential for normal lung development and is continually swallowed and expelled by the fetus. The presence of surfactant in the amniotic fluid significantly reduces the surface tension within the alveoli, making it safe for the developing lungs.
In stark contrast, when water enters the lungs, such as in a drowning situation, the high surface tension makes it extremely difficult to inhale, leading to a severe medical emergency. Infants born prematurely without sufficient surfactant can suffer from hyaline membrane disease, which makes their lungs difficult to inflate and is a leading cause of death among such infants. In cases like these, adding surfactant to the infant's breathing passages can be a life-saving treatment. In summary, while amniotic fluid is conducive to lung development due to its composition and the presence of surfactants, water's surface tension interferes with breathing, causing potentially fatal complications like hyaline membrane disease in infants who lack adequate surfactant.