Gas exchange in humans

Question 1

Describe the structure of the lungs

Answer 1

• The trachea branches into two bronchi
• The bronchi branch into bronchioles
• These bronchioles end in alveoli which are lined with cappilarries for exchange

Question 2

What are the features of an efficient gas exchange surface?

Answer 2

• Large surface area
• Thin (short diffusion distance)
• Good blood supply and good ventilation to ensure a steep concentration gradient.

Question 3

What is the purpose of the cartilage in the trachea?

Answer 3

The cartilage supports the trachea and it prevents it from closing

Question 4

What is the percentage composition of oxygen, nitrogen and carbon dioxide in inhaled air?

Answer 4

Nitrogen - 79%
Oxygen - 21 %
Carbon dioxide - 0.04%

Question 5

What is the percentage composition of oxygen, nitrogen, and carbon dioxide in exhaled air?

Answer 5

Nitrogen - 79%
Oxygen - 16%
Carbon Dioxide - 4%

Question 6

State the difference between the amount of water vapour present in inhaled air vs exhaled air

Answer 6

Exhaled air tends to contain more water vapour than inhaled air

Question 7

Why is the percentage of nitrogen in exhaled air the same as inhaled air?

Answer 7

The body does not absorb the nitrogen from the air so all the nitrogen taken in will be released again

Question 8

Describe the difference between the percentage Co2 and O2 in inhaled air and exhaled air

Answer 8

• There is a low percentage of oxygen in exhaled air as some of the oxygen is absorbed by the body
• There is higher percentage of carbon dioxide in exhaled air as extra carbon dioxide from respiration is removed

Question 9

What chemicals can be used to test for carbon dioxide?

Answer 9

Calcium hydroxide Ca(OH)2 - commonly known as limewater

Question 9

What chemicals can be used to test for carbon dioxide?

Answer 9

Calcium hydroxide Ca(OH)2 - commonly known as limewater

Question 10

How can limewater be used to test for carbon dioxide?

Answer 10

Bubble the gas you are testing for through the limewater

Question 11

Describe the effects of physical activity on breathing rate and breathing depth

Answer 11

As physical activity increases, the breathing rate increases and so does breathing depth

Question 12

Explain the effects of physical activity on breathing rate and breathing depth

Answer 12

• As physical activity increases, the rate of respiration increases, producing more carbon dioxide
• The brain detects the increased carbon dioxide concentration in the blood and sends signals to trigger an increase in breathing rate and depth to remove carbon dioxide more quickly.

Question 13

How do ciliated epithelial cells and goblet cells work together to remove debris and pathogens from the gas exchange system?

Answer 13

Goblet cells produce mucus which traps particles and pathogens and ciliated epithelial cells waft the particles towards the throat to be swallowed