Question

Given alongside is a diagrammatic sketch of a part in human lungs.
(i) Name the parts numbered 1-4.
(ii) What do the arrows 5 and 6 indicate?

Answer 1

(i) The parts numbered 1-4 are:
1 - Thin walls of capillary.
2 - Red blood corpuscles.
3 - Plasma.
4 - Thin wall of alveoli.
(ii) Arrows at 5 & 6 indicate diffusion of carbon dioxide outside and diffusing of oxygen inside respectively.