Question 3b

Are hyperresponsiveness and hyperreactivity the same or do they denote different phenomena??

Your answer

• No, they are not.

You are right. Bronchial responsiveness comprises:

• Bronchial sensitivity. If sensitivity is increased, airway narrowing occurs at low concentrations or dosages of agonist.
• Bronchial reactivity: if reactivity is increased, once the airway responds, the degree of airway narrowing per unit of agonist is greater, i.e. the slope of the dose-response curve is steeper;
• The maximal response: whilst in healthy subjects, mildly asthmatic subjects and some patients with COPD a plateau in airway narrowing is achieved at high dosages of agonist, the plateau is lower in the healthy subjects.