Question

Asthma is a common breathing disease in which inflammation in the airways of the lungs causes episodes of shortness of breath, coughing, and chest tightness. Patients with asthma often have wheezing, an abnormal sound heard on exhalation due to turbulent airflow. Turbulent airflow is caused by swelling, mucus secretion, and constriction of muscle in the walls of the airways, shrinking the radius of the air passages leading to increased resistance to airflow and making it harder for patients to exhale. An important breathing test for asthma is called spirometry. In this test, a patient takes in as deepa breath as he or she can, and then exhales as rapidly, forcefully, and for as long as possible through a tube connected to an analyzer. The analyzer measures a number of parameters and generates two graphs. 1. The graph below is a volume-time curve for an asthma-free patient, showing the volume of air exhaled, V, as a function of time, t, since the test began. V, ters t, sec 1 2 345678910 a. What is the physical interpretation of the slope of the volume-time curve? The volume VC shown on the volume-time graph is called the (forced) vital capacity (FVC or simply VC). Describe the physical meaning of Vo. b.

Answer 1

The curve shows that volume of the air exhaled is proportional to the time upto a limit. That means

At first the volume of air exhaled was the about 2 litre, after one second the volume of a exhaled was about 4 litre, at 2 second it was five litre, an after 5 second it was 5.5 litre and it remain constant after 5 secon