**Core Concept**
The aerial blood gas analysis in a bottle containing heparin causes a decrease in the values of pCO2, bicarbonate (HCO3), and pH due to the binding of heparin to calcium ions. This binding leads to a reduction in the ionized calcium levels, which in turn affects the buffering capacity of the blood and the equilibrium of the bicarbonate buffering system.

**Why the Correct Answer is Right**
Heparin binds to calcium ions (Ca2+), which are essential for the buffering capacity of the blood. The bicarbonate buffering system relies on the presence of ionized calcium to function properly. When heparin binds to calcium, it reduces the amount of ionized calcium available for buffering, leading to a decrease in the bicarbonate levels (HCO3). This decrease in bicarbonate levels causes a decrease in the pH of the blood, as the bicarbonate buffering system is unable to maintain its equilibrium. Additionally, the decrease in ionized calcium levels also affects the binding of carbon dioxide to hemoglobin, leading to a decrease in pCO2 levels.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the decrease in pCO2 is a secondary effect of the heparin binding to calcium and the subsequent decrease in bicarbonate levels. It is not the primary effect of heparin on blood gas analysis.

**Option B:** This option is incorrect because the decrease in bicarbonate (HCO3) is a direct result of the heparin binding to calcium and the subsequent decrease in the ionized calcium levels.

**Option C:** This option is incorrect because the decrease in pH is a direct result of the decrease in bicarbonate levels and the subsequent decrease in the buffering capacity of the blood.

**Clinical Pearl / High-Yield Fact**
When analyzing blood gas samples, it is essential to note that heparin can cause a decrease in the values of pCO2, bicarbonate (HCO3), and pH. This can lead to misinterpretation of the results, and it is crucial to consider the source of the blood sample and the presence of heparin when interpreting the results.

**✓ Correct Answer: D. All of the above**