8.7 Gas exchange in the alveolus

Question 1

What is the name given to the gas exchange surfaces in humans

Answer 1

Alveoli

Question 2

what is the antomy of an alveoli

Answer 2

• Grape like structures found at the end of bronchioles
• They alveoli have a large surface area to volume ration
• Their walls are made of squamous epithelium, only one cell thing, (Approx 0.2 micro milimetre) which contrinbutes to a short diffusion pathway
• This alveoli are surrounded by capillary network allows oxygen to be rapidly brought to the alveoli and carbon dioxide to be rapidly carried away.
• The capillaries are also only one cell thick (approx 0.15 micro milimetre) and further contribute to the short diffusion pathway for oxygen and co2

Question 3

Why is the diffusion pathway short

Answer 3

• The alveoli and once cell thing approx 0.20 micro milimeteres
• The capillaries are 0.15 micro millimetres
• The maximum distance between the capillary wall and the alveolus is 0.02 micro milimetres
• 0.2 + 0.15 + 0.02 = 0.37 micro millimetres

Question 4

What is the average size of the

Question 5

What blood vvessel carries oxygenated blood to the capillaries surrounding the alveoli

Answer 5

Pulmonary artery

Question 6

What blood vessel carries carbo dioxide from the capillary network surrounding the alveoli

Answer 6

Pulmonary vein

Question 7

What % of the air that we inhales contains oxygen?

Answer 7

20%

Question 8

What percent of air that we exhale contains oxygen

Answer 8

16%

Question 9

What percent of air that we inhale is absorbed

Answer 9

20% inhaled - 16% exhaled = 4% absorbed.

Question 10

How does the percentage of oxygen absorbed when inhaled by bony fish compare with the percentage of oxygen inhaled by humans

Answer 10

• Bony fish remove 80% of the oxygen passing over their gills and humans absorb 20% of oxygen through their alveoli.
• This means that bony fish are 4 times more efficient at absorbing oxygen compared to humans