Exchange of gases in lungs

Question 1

How is concentration gradient maintained in alveoli

Answer 1

Continuous blood flow in capillary- new blood reaches alveoli which is limited in O2 and leaves rich in O2
Movement of air in/out of lungs and alveoli (breathing)- air which has picked up CO2 leaves the lungs and New air rich in O2 enters lungs

Question 2

Why are lungs well suited to their function (5)

Answer 2

-Alveoli= little air sacs
Increase internal surface area
Increases gas exchange on a shorter time
-Network of capillaries surround alveoli
Blood= closer to air and allows faster exchange
-capillary and alveoli= 1 cell thick
Shorter distance, faster and easier exchange + diffusion
-Lungs= deep inside chest cavity
Prevents evaporation
Keeps moisture which allows gas to diffuse through membrane
-Lungs= made of elastic- like muscle
Increases/ decreases volume to allow air to flow in/out