9.1. The gas exchange system
A subsection of Biology, 9700, through 9. Gas exchange
Listing 10 of 240 questions
Some pathogens can enter the human body through the gas exchange system. The epithelial lining of the gas exchange system is adapted for defence against pathogens. List the structures in the gas exchange system that have a ciliated epithelial lining. Name the cells in the ciliated epithelium that synthesise and secrete mucus. Alveolar macrophages are cells of the immune system. They have an important role in defence against respiratory infections. The infectious lung disease, pneumonia, can be caused by Streptococcus pneumoniae. Most healthy people inhaling air containing these bacteria do not become ill because of the action of the alveolar macrophages. Outline the mode of action of an alveolar macrophage in response to the presence of S. pneumoniae. You may use diagrams with notes to help your answer. Irritants in tobacco smoke can contribute to emphysema, one of the chronic obstructive pulmonary disorders (COPD). In emphysema, the alveoli lose their ability to recoil on expiration and can burst. Suggest how the structure of the alveolar wall changes so that an alveolus bursts. Some alveolar cells produce a surfactant that helps to prevent the collapse of alveoli on exhalation. Too much surfactant decreases the efficiency of gas exchange in the alveoli. A glycoprotein known as GM-CSF is released by some cells of the immune system when there is too much surfactant in the alveoli. Excess surfactant is then broken down by alveolar macrophages. Receptors for GM-CSF are on the cell surface membranes of alveolar macrophages. Explain how maintaining the correct quantity of surfactant in the alveoli is the result of a cell signalling mechanism.
9700_s17_qp_22
THEORY
2017
Paper 2, Variant 2
View
Questions Discovered
240