Hyperventilation involves expelling carbon dioxide from the body, so the amount of  in the blood would decrease. Since carbon dioxide is directly associated with acid and  ion production, pH would increase upon elimination of .

Diabetic ketoacidosis is a condition that can occur in people who have diabetes. In this situation, there is a deficiency in insulin production. Consequently, the glucose that is present in the blood has no way of entering cells. These cells, in turn, become starved for energy, causing the body to burn fat and produce acidic ketone bodies as an alternative energy source. The energy deficit that cells experience as a result of not having access to glucose causes significant production of these acidic ketone bodies. In fact, so many of these ketone bodies are produced that it overwhelms the body's normal pH buffering capacity, and thus the blood can become dangerously acidic. High levels of intracellular glucose is incorrect because the lack of insulin causes glucose to be unable to enter these cells. Gluconeogenesis in the liver is also increased because the energy starved cells alert the body that they need energy. The body is "tricked" into "thinking" that the cells aren't getting energy due to a shortage of glucose, even though plenty of glucose is actually available. Thus, gluconeogenesis exacerbates the high blood glucose levels. Fat breakdown in the body is also increased. It is this breakdown of fat that provides the ketone bodies as an alternative fuel source for the body. Glucagon output is also increased because, as explained above, the body "thinks" it is energy starved due to there not being enough glucose even though there is plenty. This hormone increases gluconeogenesis and fat breakdown, as described above.

Thus the ratio of  is equal to , or the ratio of  is equal to 

The best buffering capacity occurs when pH = pKa. When this is true, the ratio of ionized to unionized form of the buffer is 1:1. Thus the solution can best resist changes in pH, as hydrogen ions can be quenched or donated to solution to resist change. Acetic acid would have almost the same buffering capacity since its pKa is almost as close to 4.0 as that of formic acid.

Low blood pH suggests that the patient has high concentration of hydrogen ions. To solve this question, we need to look at the following reaction, which represents the major blood buffer system:

One way the body controls the amount of hydrogen ions in the blood is by altering the amount of carbon dioxide. Recall that, according to Le Chatelier’s principle, increasing carbon dioxide will push the reaction the right and increase hydrogen ion concentration whereas decreasing carbon dioxide will decrease hydrogen ion concentration.

Body controls carbon dioxide levels via breathing. Hyperventilation refers to increased breathing whereas hypoventilation refers to decreased breathing. During hyperventilation the person breathes out excess carbon dioxide (decreasing the hydrogen ion concentration). During hypoventilation, on the other hand, a person breathes slowly and retains carbon dioxide (increasing the hydrogen ion concentration). The patient in this question has low blood pH (high hydrogen ion concentration); therefore, of the options, the patient must be hypoventilating.

A buffer system occurs when equal amounts of a weak acid and its conjugate base (or vice versa) is added together. Maintaining blood pH is a very important aspect in maintaining homeostasis. The body does this utilizing the carbonic acid/bicarbonate buffer system. The concentrations of the base and acid are altered accordingly to maintain a constant blood pH.

Hydrochloric acid is found in the stomach to maintain an acidic pH, phosphoric acid does play a role in buffering the blood, but is not the major buffer. Acetic acid is found in vinegar and does not play a major role in regulating blood pH.

Blood pH is maintained via the lungs and the kidneys. Lungs alter the amount of carbon dioxide expelled to maintain blood pH. Consider the reaction below.

Carbon dioxide is decreased when pH is low (high hydrogen ion concentration). Decreasing carbon dioxide will shift the reaction to the left and decrease the hydrogen ion concentration. Similarly, the body compensates for high blood pH by increasing carbon dioxide.

Kidneys alter blood pH by increasing or decreasing the excretion of bicarbonate ions. Using the reaction above, we can determine that increasing bicarbonate ion in blood will decrease hydrogen ion concentration whereas decreasing bicarbonate ion will increase hydrogen ion concentration. To combat high blood pH (low hydrogen ion concentration), the bicarbonate ion needs to increased in the blood. The kidneys do this by decreasing the excretion of the bicarbonate ions.

pH is calculated via the following equation:

refers to the concentration of hydrogen ions in the solution, which in this case is the same as the concentration of the acid since hydrochloric acid is a strong acid and will fully dissociate in solution. Thus, we have:

Buffering capacity refers to how well a buffer works. A buffer is a substance that maintains a specific pH regardless of added acid or base. Thus, buffering capacity refers to how well a buffer maintains the pH of a solution despite the the effects of added acid or base. The other choices do not apply to this definition.

Recall the equation for pH. Here is the calculation that should be performed: