Outline the ways in which tobacco smoking can promote atherosclerosis.
Fig. 2.1 shows a scan of the lungs of a person with emphysema. One feature common to the labelled damaged regions is loss of the elastic fibres of the alveoli. Another feature is a higher number of macrophages and neutrophils. State the general role shared by macrophages and neutrophils.
Fig. 2.1 shows a scan of the lungs of a person with emphysema. One feature common to the labelled damaged regions is loss of the elastic fibres of the alveoli. Another feature is an increased number of macrophages and neutrophils.
Suggest how the loss of the elastic fibres could lead to the enlargement of the lung shown in Fig. 2.1.
The synthesis and release of elastase enzymes by macrophages and neutrophils is an important part of the development and progression of emphysema. Elastase breaks down the protein elastin, the main component of elastic fibres.
Explain the meaning of an enzyme.
Elastase has an active site with a specific shape. The mode of action of this enzyme supports the lock and key hypothesis. Explain the mode of action of elastase. You may use the space below to draw a diagram or diagrams to help you answer.
Two elastase inhibitors made in the body are TIMP-1 and A1AT. • macrophage elastase is inhibited by TIMP-1 • neutrophil elastase is inhibited by A1AT. The inhibitors can be inactivated by the elastase enzymes: • macrophage elastase can inactivate A1AT • neutrophil elastase can inactivate TIMP-1. In healthy lungs, the activity of elastase enzymes is regulated. Tobacco smoke can disrupt this regulation.
One effect of tobacco smoke is to bring about changes in the structure of A1AT, a competitive inhibitor. Suggest how structural changes to A1AT will affect its mode of action.
A1AT is a protein. Some non-smokers have a mutation in the gene coding for A1AT and are at risk of developing emphysema as there is a lack of A1AT in the lung tissue. Explain why a lack of A1AT in these non-smokers places them at risk of developing emphysema.
Tobacco smoke is known to cause increased production of macrophage elastase. $MMP12$ is the gene coding for macrophage elastase. Copies of this gene are produced as messenger RNA (mRNA). Describe how this mRNA is used in translation to produce macrophage elastase.