Final answer:
Airway resistance is increased by smooth muscle contraction, mucus secretion, and asthma, which all lead to narrowing and blockage of the airways, impeding airflow.
Step-by-step explanation:
Airway resistance is increased by several factors. The correct answers that cause an increase in airway resistance are: smooth muscle contraction which narrows the airways, mucus secretion which can block the airways, and conditions like asthma which can lead to inflammation and constriction of the airways. While increasing transpulmonary pressure does affect lung volumes, it does not directly increase resistance in the context of this question. Therefore, the correct answer is e) Answers a, b, and d are correct.
It's crucial to understand that resistance is a force that opposes motion, in this context, the flow of gases through the lungs. Conditions such as asthma can result in inflammation of the airways, increased mucus secretion, and smooth muscle contraction, all of which increase resistance by narrowing the airways and obstructing airflow. Inflammation and obstruction of the airways prevent proper movement of gases, creating challenges for individuals with respiratory conditions.