Final answer:
Myocardial ischemia is marked by the buildup of lactic acid due to anaerobic conditions, causing a decrease in blood pH. Lactic acid is produced when oxygen is scarce, and cells resort to anaerobic metabolism. The bicarbonate buffer system helps regulate blood pH by converting carbon dioxide into carbonic acid, which further dissociates into bicarbonate and hydrogen ions.
Step-by-step explanation:
Inadequate supply of oxygen to the myocardium, also known as myocardial ischemia, is indicated by the accumulation of lactic acid. This occurs under anaerobic conditions, such as during vigorous exercise or when there is a blockage in the coronary arteries that supply blood to the heart. When oxygen levels are low, cells can no longer undergo aerobic respiration effectively and must rely on anaerobic processes, which convert pyruvate to lactate, generating lactic acid as a by-product. The build-up of lactic acid can lead to a decreased pH of the blood, indicating the stress on the myocardial tissue due to the lack of sufficient oxygen.
As part of the body's bicarbonate buffer system, carbon dioxide is rapidly converted into carbonic acid within red blood cells, which dissociates into bicarbonate ions and hydrogen ions. The production of lactic acid and CO₂ during exertion not only indicates strenuous activity but also facilitates the release of O₂ from oxyhemoglobin, which can temporarily compensate for the lower oxygen availability by providing oxygen to the tissues that need it most.