why are alevelio are so small and uncountable in number
Answers
Answer:
The basic answer is - To increase the surface area for gaseous exchange.
Explanation:
The alveolar walls helps in gaseous exchange as they are surrounded by blood capillaries through which gases escapes and enters. Now imagine a large balloon filled with gas and the gas can only escape from walls. And imagine large number of small balloons surrounded by blood capillaries.
#what you think where will be more transfer of gases.
( consider the air pressure that will build in both cases ).
As you can imagine there is increase in surface area due to many small alveoli and pressure can be more evenly applied resulting in to more gaseous transfer.
thats why alveoli are small and more in number rather than one large balloon.
#More..Small nature of alveoli is result of there terminal presence which helps in better filtering of air.