Question

How are the lungs designed in human beings to maximisethe the area for exchange of gases?

Answer 1

Each lung has highly branched respiratory respiratory tract known as Respiratory tree.A primary bronchus divedes into secondary bronchi ,secondary bronchus into segmental bronchi , segmental into bronchioles which further divide into terminal bronchioles , respiratory bronchioles ,alveolar sacs and alveoli.Alveoli are polyhedral pouches which are extremely thin walled and possess a network of blood vessels over their surface.There are about 300million alveoli in each lung.The surface of an alveolus acts as Respiratory surface.As there are large no. of alveoli ,a very large area for respiratory surface becomes available about 80metresquare.

Answer 2

♤ In the lungs, the air passage that divides into smaller and smaller tubes called bronchi which form bronchioles .

♤ The bronchioles terminate in the balloon like structure called alveoli.

♤ The alveoli present in the lungs provide maximum surface for exchange of gases.

♤ The alveoli have very thin walls and contain an extensive network of blood vessels to facilitate exchange of gases.