11.1 Gas Exchange in Humans

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A study was carried out that looked at the movement of the diaphragm during normal breathing.

Fig. 1 shows the diaphragm movement in a healthy 55-year-old male.

Fig. 1

Calculate the breathing rate of the individual shown in Fig. 1.

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[1]

For the stage marked Y on Fig. 1, name a muscle other than the diaphragm involved at this stage and identify its state. 

[2]

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Fig. 2 shows the results of another participant in the study.

This individual is a 57-year-old male with emphysema, a lung condition that reduces gas exchange and causes significant illness.

Fig. 2

Contrast the graph shown here with Fig. 1 as shown in part (a).

[2]

Suggest an explanation for the differences between the graphs.

[2]

Events such as surgical trauma or nerve degeneration can lead to weakness or even paralysis of the diaphragm.

Suggest the effect that this would have on ventilation.

Fig. 1 depicts a section of the human gas exchange system.

Fig. 1

State the name of Organ 1 and describe its role in breathing out.

In normal and healthy lungs, an effective oxygen supply is maintained between the alveoli and the lung capillaries.

Describe and explain how this is maintained.

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Fig. 2 shows the changes in the volume of air in a woman’s lungs while breathing.

Fig. 2

Explain how Fig. 2 shows that the woman was breathing out between times W and X.

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Muscle action during ventilation is described as antagonistic.

Outline what this means with reference to one example during breathing.

Fig. 1 shows a diagram of the gas exchange system.

Fig. 1

Complete the labelling of Fig. 1 using the words from the list.

bronchiole         diaphragm         intercostal muscle         trachea

Alveoli are gas exchange surfaces.

State two features that make alveoli good gas exchange surfaces.

There is less oxygen in expired air than in inspired air.

Describe two other ways in which expired air is different from inspired air.

[2]

State the name of a process that uses oxygen in cells.

State an example of a cell and an organ from the gas exchange system.

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A genetic condition called Canine Tracheal Collapse affects certain breeds of domestic dog.

Affected dogs experience difficulty in breathing due to a weakness in the walls of the trachea.

Suggest, with a reason, which type of tissue is affected by this genetic disorder. 

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Table 1 shows some differences between inhaled and exhaled air.

Table 1

Calculate the percentage difference in oxygen content of exhaled air compared to inhaled air. 

The presence of bronchioles, alveoli and blood capillaries within a lung all reduce its overall volume.

Explain how these structures actually improve the performance of the lung as a gas exchange organ. 

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Explain the roles of the cilia and mucus in protecting the breathing system.