Question

 3a. List three conditions which decrease lung compliance and how these conditions arise.  

 3b. Why is it important that alveolar air is humidified? Please explain.  

 3c. What is a ventilation perfusion mismatch? Is there a ventilation to perfusion ratio mismatch in people who smoke? If so please explain.  

 3d. Considering the following information you learned about the protective role of mucous and cilia in the respiratory passage ways, why are people who smoke more prone to respiratory infections than people who don't smoke? Please explain.  

Answer 1

3a) lung compliance is the lung's ability to stretch and expand. There are many conditions that may cause decrease in the lung compliance like

• Pneumonia:- at higher transpulmonary pressures, the consolidated air spaces doesn't inflate easily which causes volume loss at higher volume. This volume loss reduces the lung compliance
• Tension pneumothorax:- changes in lung capacity causes alteration in thoracic wall recoil
• Pulmonary fibrosis: during fibrosis, lung lose their distensibility and become stiffer
• Pulmonary edema
• Intrinsic lung disease:- also causes decreased lung compliance
• Ascites

3b)it is important that the alveolar air is humidified because humidification of inspired helps to prevent damage to the delicate tissues in the respiratory system.

Also the water vapour reduces the partial pressure of oxygen in the lungs.

It prevents the disruption of the lung epithelium, also prevents atelectasis.

3c) ventilation perfusion mismatch ( V/Qratio) is a abnormal condition of lungs in which one or more part of the lung receives oxygen without blood flow or blood flow without oxygen. This can be due to any airway obstruction or obstruction of blood vessels ( blood clot)

Normal V/Q ratio is 0.95

Cigarette smoking also cause ventilation perfusion mismatch. Because cigarette smoke contains other components like nitric oxide which can interfere with the normal vascular mechanism resulting in hypoxic vasoconstriction which leads to mismatch in the ventilation perfusion ratio. Also the components in cigarette smoke induces chemotaxis and activates the neutrophils and macrophages which cause oxidative stress.

3d) the role of mucus and the cilia in the respiratory tract is highly important. Because the cilia ( hair like projections in the respiratory tract) which helps to move the microbes and the debris up and out of the airways. Whereas the mucus produced by the goblets cells (specialized cells scattered thein the epithelial lining) helps to protect the lining of the bronchus and also traps the microorganisms from entering into the lungs.

But in smokers, the smoking affects the functioning of cilia. It can cause temporary paralysis or even kills cilia.

Smoking causes hyperplasia of the goblet cells which cause increase in the size and number of goblet cells resulting in the increased mucus production which may obstruct the airways.