Blood pH is normally regulated by the respiratory system to

Blood pH is normally regulated by the respiratory system to control the level of CO_2 (g) and by the urinary system to control the levels of HCO_3^- and non-volatile acids in the blood. Given the overall reaction, CO_2 (g) + H_2 O (l) H_2 CO_3 (aq) HCO_3^- (aq) + H^+ (aq), what effect would each of the following have on blood pH? Explain. a. Hyperventilating b. Holding your breath for an extended period of time c. Chronic diarrhea d. Excessive ingestion of baking soda One of the effects of Topamax is to inhibit carbonic anhydrase. Predict the effect of Topamax on the function of each of the following cells: a. Osteoclasts (bone) b. Parietal cells (stomach) c. Red blood cells (blood) d. Epithelial cells of the proximal tubules (kidney) The carbonic anhydrase in proximal tubule epithelial cells are particularly sensitive to inhibition by Topamax. Use the diagram of transport in the epithelial cells of the proximal tubule provided on the next page* and your understanding of the function of the kidney to provide a step-by-step explanation of how the inhibitory action of Topamax caused the disturbances in Mary\'s blood chemistry.

Solution

Qu-3:

Part-a:

Hyperventilation (reduces CO2) is increases the pH of blood (metabolic alkalosis). The equilibrium shifts towards H2CO3 (carbonic acid) formation

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

During hyperventilation, the CO2 levels in the circulation decrease, so the dissociation of carbonic acid (H2CO3) into bicarbonate and hydrogen ions reduces. The decreased H+ level raises the blood pH (More H+ ions means less pH and vice versa). This is leading to right shift in the oxygen dissociation curve due to high loading of oxygen at alveolar level followed by high unloading at tissue level.

Part-b:

Holding your breath is going to increase in CO2 level that decreases PH of the blood due to formation of more H+ ions result in decrease in PH of the blood finally loading of oxygen is lower due to lower affinity of hemoglobin to oxygen. These events are leading to decreased loading of oxygen finally right shift in oxygen binding-dissociation curve

Part-c:

Chronic diarrhea

Intense diarrhea is leading to more loss of alkaline intestinal secretions (mainly bicarbonate) resuslt in high H+ and low blood pH (metabolic acidosis)

Excessive ingestion of baking soda:

Th above consumption of bicarbonate increases blood pH (due high CO2 level) due to high Carbonic Acid-Bicarbonate Buffer System

Explanation:

The constant pH of the blood is maintained via “blood-bicarbonate duffer system” about 7.4. This pH would not decrease under normal metabolic conditions of respiration. If the metabolic conditions are altered due to, any abnormal phases such as metabolic disorders may result in lowering of blood pH

The bicarbonate buffering system of In the cellular respiration, involves an acid & base homeostatic mechanism further involving the equilibrium balance of carbonic acid(H2CO3), bicarbonate ion (HCO3-), and carbon dioxide (CO2) in order to maintain isotonic pH (7.4) in the blood and duodenum, among other tissues, to enable appropriate metabolic function. This reaction is catalyzed by carbonic anhydrase, when cellular carbon dioxide (CO2) (lungs) reacts with water (H2O) to form carbonic acid (H2CO3), which in turn rapidly dissociates to form a hydrogen ion (exists in the solution as hydronium ion, H3O+) and bicarbonate ion (HCO3) as described in the following reaction.