Question

What happens to urinary bicarbonate excretion when a person hyperventilates? How might this response be helpful?

Short answer

When a person hyperventilates, urinary bicarbonate excretion increases due to the decreased carbon dioxide concentration in the blood, which causes a shift in the bicarbonate and carbon dioxide equilibrium. This response helps maintain a stable pH environment for optimal functioning of enzymes and cells by restoring the acid-base balance of the blood.

Step-by-step solution

Define hyperventilation

Hyperventilation is the condition where a person breathes more rapidly or deeply than normal, leading to a decrease in the partial pressure of carbon dioxide in the blood (termed as hypocapnia). This can cause respiratory alkalosis, a state where the blood pH increases due to the decreased concentration of carbon dioxide in the blood.

Understand acid-base balance

The acid-base balance is the body's way of maintaining a stable pH environment for optimal function of its enzymes and cells. The bicarbonate (HCO3-) and carbon dioxide (CO2) equilibrium plays an essential role in determining blood pH levels, as represented by the following equation: \[CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons H^+ + HCO_3^-\]

Relationship between hyperventilation and urinary bicarbonate excretion

When a person hyperventilates, the concentration of carbon dioxide in the blood decreases, causing a shift in the above equation to the left. This leads to a decrease in hydrogen ion (H+) concentration and an increase in bicarbonate ion (HCO3-) concentration. The kidneys respond to this change by excreting more bicarbonate ions to compensate for the decreased hydrogen ion concentration.

Explaining the helpful response

Urinary bicarbonate excretion during hyperventilation can be helpful because it helps the body maintain a stable pH. By excreting excess bicarbonate ions, the kidneys are working to restore the balance between bicarbonate and carbon dioxide concentrations in the blood, thus ensuring that the body maintains an optimal pH level for the proper functioning of enzymes and cells. In summary, when a person hyperventilates, urinary bicarbonate excretion increases as the kidneys work to restore the acid-base balance of the blood, helping maintain a stable pH environment for the optimal functioning of the body's enzymes and cells.