Gas Exchange

The Weibel Lung model describes how each airway divides into two.

Name the airways in generation 1, labelled X in Fig. 6.1, that branch from generation 0.

The airways are well supplied with blood. However, the airways from generation 0 to generation 16, shown in Fig. 6.1, are not able to carry out gas exchange.

Suggest why the airways from generation 0 to generation 16 are not able to carry out gas exchange.

State the relationship shown in Fig. 6.2 between airway diameter and airway generation for the Weibel Lung model data.

With reference to the data in Fig. 6.2, explain whether HP gas MRI could be a useful alternative to HRCT in obtaining airway diameter measurements.

The luminal surface shown in Fig. 5.1 is not clearly defined and appears slightly blurred.

State why the luminal surface of the bronchial epithelium appears slightly blurred, even though the resolution of the image is good.

Some cells of the bronchial epithelium shown in Fig. 5.1 appear darker than others. For example, cell D appears darker than cell L.

With reference to the bronchial epithelium shown in Fig. 5.1, explain why some cells, such as cell D, appear darker and other cells, such as cell L, appear lighter.

In Fig. 5.1 the tissue in box B is cartilage.

The tissue shown in box A is different from the tissue in box B.

Outline the differences in the structure and function of tissue A compared with tissue B.

Name the airways that branch from the trachea to enter the lungs.

The lower part of the trachea receives blood from arteries that branch from the aorta. Different arteries carry blood from the heart to the alveoli of the lungs.

State the differences between the arteries supplying the lower part of the trachea and the arteries that supply blood to the alveoli of the lungs.

In Fig. 1.1, one of the tissues in the trachea is labelled T.

Describe the structural features of tissue T visible in Fig. 1.1.

Identify structure X in Fig. 1.1 and outline the features that helped your identification.

structure X = ______

Table 4.1 shows the changes that occur in the number of goblet cells in the epithelium of the different structures of the gas exchange system.

Table 4.1

Goblet cells produce mucus, which is important in maintaining the health of the airways.

The smallest bronchioles closest to the alveoli are known as respiratory bronchioles.

Suggest and explain why respiratory bronchioles do not have any goblet cells.

There are structural differences between the epithelium of the bronchiole and the epithelium of an alveolus.

Describe the differences between the epithelium of bronchioles and the epithelium of alveoli, other than differences in the number of goblet cells.

Tissue X, shown in Fig. 4.1, is located in the wall of the bronchiole.

Name tissue X and outline the function of tissue X in the bronchiole.

tissue X = ______

State the feature visible in Fig. 3.1 that identifies the structure in the centre of the image as the bronchus and list other visible features that help to confirm this identification.

feature to identify the bronchus ______

other features ______

Identify the structure labelled J in Fig. 3.1.

State the evidence visible in Fig. 3.1 that supports your answer.

The ciliated epithelium labelled in Fig. 3.1 consists of goblet cells and ciliated epithelial cells.

Outline how goblet cells and cilia work together to maintain healthy lung tissue.

Descriptions of some parts of the gas exchange system are shown in Table 1.1.

Complete Table 1.1 to:

• state the name of the part described
• write a letter from Fig. 1.1 to identify each part.

Table 1.1

Tobacco smoke contains a number of compounds which can affect the body.

State the appropriate term that matches each of the statements A to E.

A The type of chemical that causes mutation of genes that control the cell cycle.

B A component that causes a short-term increase in blood pressure.

C A component that reduces the carrying capacity of haemoglobin for oxygen.

D A component that increases the production and secretion of mucus from goblet cells.

E A component that causes a short-term increase in heart rate.

With reference to Fig. 2.1, list the two WHO regions where smokers are at the highest risk of developing diseases of the gas exchange or cardiovascular systems.

With reference to Fig. 2.1, explain why smoking a popular brand of cigarette from the AFRO region is more likely to increase the risk of blood clots forming than smoking a popular brand of cigarette from the EURO region.

One short-term effect of cigarette smoking is a decrease in the supply of oxygen to body tissues.

Describe and explain why cigarette smoking leads to a decrease in the supply of oxygen to body tissues.

Smooth muscle and cartilage are two of the tissues found in the walls of structures of the gas exchange system of mammals.

Complete Fig. 5.1 to show the distribution of these tissues in the gas exchange system of mammals.

Choose from the four structures listed below.

alveolus      trachea      bronchus      bronchiole

Tobacco smoke is known to be one of the causes of lung cancer and chronic obstructive pulmonary disease (COPD).

Outline how tobacco smoke may cause lung cancer.

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Fig. 5.2 shows a section through the wall of one part of the gas exchange system in a person with COPD.

The tissue in the section of the wall labelled X is the result of changes to the original healthy tissue lining the lumen of the gas exchange system. The tissue shown is not scar tissue and is not a tumour.

The area labelled X on Fig. 5.2 is different in appearance to the original healthy tissue in the same part of the gas exchange system.

Describe these differences.

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Fig. 6.1 shows the first three structures of the human gas exchange system through which air from the external atmosphere passes during inhalation.

Complete Fig. 6.1 to show the pathway that air takes during inhalation.

The inhalation of tobacco smoke can lead to chronic obstructive pulmonary disease (COPD). COPD is a term used to describe a collection of lung diseases.

Name two smoking-related diseases associated with COPD.

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Explain how nicotine and carbon monoxide contribute to damage to the coronary arteries.

nicotine ______

carbon monoxide ______

Explain how the two by-passes shown in Fig. 5.1 provide an effective treatment for coronary heart disease.

The cost of treating heart disease is very high.

Suggest the steps that governments could take to reduce heart disease in the population.