Final answer:
In healthy individuals, air resistance primarily occurs in the upper airways, while diseases linked to smoking, such as emphysema, impact the smaller, peripheral airways by increasing resistance and compliance due to damage. This results in decreased gas exchange efficiency.
Step-by-step explanation:
In health, the major contributor to air resistance lies in the upper airways, whereas in disease caused by smoking the contributor lies in the smaller, peripheral airways. This distinction is important because the size and health of the airway dramatically affect the resistance to airflow. In general, healthy airways are more compliant, allowing for easier airflow, but when obstructive diseases like emphysema, tied to smoking, damage the airways, they become less elastic and the resistance increases. Obstructive diseases are characterized by increased compliance due to the destruction of alveolar walls and loss of elastic fibers, leading to higher air entrapment.
Conditions such as asthma and emphysema cause the airways to narrow and obstruct airflow, meaning resistance increases because it becomes harder for air to flow through the airways. In contrast, examples of restrictive diseases like fibrosis show decreased lung compliance, resulting in stiff airways that collapse during exhalation, trapping air in the lungs. Both changes in compliance and resistance negatively impact the body's ability to conduct efficient gas exchange, and in cases of chronic smoking, the airway damage significantly hampers this process.