Question

1. significance of forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC)

2. how most carbon dioxide travels from tissues to lungs

Answer 1

1. FEV1 is the volume of air expired fforecefully in first second of forced expiration. Forced vital capacity is the volume of air expired forcefully in forced expiratory phase.

FEV1 is reduced in Obstructive lung disease while FVC remains normal or slightly decreased,. This is because of entrapement of the air in the lung that causes hyperinflation of th lung. FEV1/FVC ratio is reduced.

In restrictive lung diseases, FEV1 and FVC both are reduced hence the ratio of FEV1/FVC remains normal.

2. transport of carbon dioxide:

1) Carbon dioxide is more soluble in blood than oxygen. About 5 to 7 percent of all carbon dioxide is dissolved in the plasma.
2) carbon dioxide can bind to plasma proteins or can enter red blood cells and bind to hemoglobin. This form transports about 10 percent of the carbon dioxide.

3) the majority of carbon dioxide molecules near about 85% are carried as part of the bicarbonate buffer system. In this system, carbon dioxide diffuses into the red blood cells. Carbonic anhydrase (CA) within the red blood cells quickly converts the carbon dioxide into carbonic acid (H2CO3). Carbonic acid is an unstable intermediate molecule that immediately dissociates into bicarbonate ions
and hydrogen (H+) ions.
When the blood reaches the lungs, The H+ ion binds to the bicarbonate ion. This produces the carbonic acid intermediate, which is converted back into carbon dioxide through the enzymatic action of CA. The carbon dioxide produced is expelled through the lungs during exhalation