ANATOMY

Detailed explanation-1: -Moist surface of respiratory structures such as the moist surface of alveoli. Thin respiratory structures such as the walls of alveolus and blood capillaries which are one cell thick. Large surface area of respiratory structures such as the surface area of millions of alveoli.

Detailed explanation-2: -Efficient gas exchange systems must: have a large surface area to volume ratio • be thin • have mechanisms for maintaining steep concentration gradients across themselves • be permeable to gases.

Detailed explanation-3: -Thin walls, a moist inner surface, a large combined surface area, and a rich blood supply are all characteristics of a respiratory surface.

Detailed explanation-4: -Adaptations of the alveoli: Moist walls-gases dissolve in the moisture helping them to pass across the gas exchange surface. Permeable walls-allow gases to pass through. Extensive blood supply-ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs.

Detailed explanation-5: -the structures through which gas exchange occurs must be thin so the diffusion can occur easily. this membrane must be kept moist. to ensure enough exchange there must be a rich blood supply present ( 760 square feet) More items