Why does the internal structure of the lungs has an extensive surface area?

Answer 1

Lungs have large interior surface area because they're not just big bags. On the inside, they're full of a spongy network of smaller, smaller, and ever-smaller air passage-ways, ending in tiny dead-end sacs called alveoli. Every tube, sac, detour, fork in the road, branch, split-off, and tiny dead-end has walls with surface area.

The speed at which oxygen can be transferred into the blood stream depends on the collective surface area of the alveoli contained in the lung. That is why we have alveoli, filling the lungs like a sponge. We need the oxygen collected by the bloodstream in order to burn the energy that our body has stored, and a faster input of oxygen allows a faster burning of that energy - hence the advantage of having that maximized surface area.

One common result of many years' smoking is that the wall between two adjacent passage-ways shrivels up and disappears, and those two passageways merge and become one. That reduces the surface area in that tiny part of the lung. When it progresses to thousands of tiny parts of the lung, you start to notice it ... you're short of breath, because the interior surface area of your lung is reduced, and you can't grab enough of the oxygen from the air you take in. That's the condition called 'emphysema'.

Answer 2

Tiny sacs that line the ends if our bronchioles, called alveoli. By enlarging the surface area-to-volume ratio, a greater volume of gases can be exchanged in the lungs.

Answer 3

The lungs have an extensive surface area, measuring around 30-50 square meters. This is in large part due to alveoli, which are smaller structures within each lobe of the lung.