Asthma affects about seven percent of the population. During an asthma attack smooth muscle cells in the bronchi constrict, the airways become inflamed and swollen, and breathing becomes difficult. What effect might an asthma attack have on blood pH?

A. pH goes down
B. pH goes up
C. No change in blood pH

My first instinct is to guess that the pH will go down because pCO2 will rise. However some stuff that I have read says that the blood pH rises initially--so I am unsure of the overall effect on blood pH. I am still fairly certain it's A, but would just like some confirmation?

H2O + CO2 <==> H2CO3 <==> H^+ + HCO3^-

So if we restrict the breathing, CO2 rises, and Le Chatelier's Principle says that will force the reaction to the right; therefore, my best guess is that the blood pH will decrease (become more acid).

To determine the effect of an asthma attack on blood pH, it is important to understand the respiratory system's response during an attack. During an asthma attack, the bronchi constrict, causing difficulty in breathing. This constriction reduces the air exchange in the lungs, leading to a decrease in the removal of carbon dioxide (CO2) from the body.

When levels of CO2 increase in the bloodstream, it combines with water to form carbonic acid (H2CO3) through the following reaction:
CO2 + H2O → H2CO3

Carbonic acid then dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+), resulting in an increase in the concentration of hydrogen ions:
H2CO3 → H+ + HCO3-

An increase in hydrogen ion concentration leads to a decrease in blood pH, making it more acidic. Thus, in the case of an asthma attack, where there is reduced air exchange and an increase in CO2 levels, the blood pH is expected to go down (A. pH goes down).

It's important to note that there may be some initial compensatory mechanisms triggered by the body, such as hyperventilation, to decrease CO2 levels temporarily. This might initially result in a slight increase in blood pH, but eventually, the prolonged increase in CO2 levels will cause the blood pH to decrease.