GAS EXCHANGE IN THE LUNGS

Question 1

How many alveoli are there in each lung

Answer 1

300 million

Question 2

Why is gas diffusion between alveoli and blood very rapid (6)

Answer 2

1) red blood cells are slowed as they pass trhough pulmonary capillaies - allowing time for diffusion
2) distance between alveolar air and red blood cells is reduced (as red blood cells flattened against capillary walls)
3) walls of alveoli and capillaries are very thin
4) alveoli and pulmonary arteries have large total SA
5) steep concentration gradient of gases is maintained

Question 3

How is a steep concentration gradient maintained

Answer 3

breathing constantly ventilates lungs, heart constantly circulates blood around alveoli, constant blood flow through pulmonary capillaries

Question 4

What are the alveoli surrounded by a network of in the lungs

Answer 4

capillaries

Question 5

What is the path of 02 through the lungs

Answer 5

into lungs, into alveoli, diffuses out of alveoli, across alveolar epithelium and capillary endothelium, into haemoglobin in the blood

Question 6

What are cappilary endothelium

Answer 6

type of epithelium that forms the capillary wall

Question 7

What does correlation not guarantee

Answer 7

causation (casual relationship)