The main reason we are slightly alkaline in our circulatory system is due to bicarbonate.

Yes, that's correct! The slightly alkaline nature of our blood and circulatory system is primarily due to the presence of bicarbonate ions (HCO₃⁻). Bicarbonate plays a crucial role in maintaining the body's pH balance through a mechanism known as the bicarbonate buffer system. Here’s how it works:

1. Buffer System: The bicarbonate buffer system helps stabilize the pH of the blood. When there is an excess of hydrogen ions (H⁺) in the blood, bicarbonate can react with these ions to form carbonic acid (H₂CO₃), which can then dissociate into water (H₂O) and carbon dioxide (CO₂). This reaction helps reduce acidity.

2. Respiration and Metabolism: During cellular metabolism, carbon dioxide is produced and enters the blood. This CO₂ can react with water to form carbonic acid, which then dissociates to form bicarbonate and hydrogen ions, thus influencing pH.

3. Kidney Regulation: The kidneys contribute to the regulation of bicarbonate levels in the blood by either excreting excess bicarbonate or conserving it, which also helps control the acidity or alkalinity of the blood.

4. Normal pH Range: The normal pH range of human blood is about 7.35 to 7.45, which is slightly alkaline. Maintaining this pH is vital for proper physiological function, as many enzymes and biochemical reactions in the body are pH-sensitive.

Overall, the bicarbonate system is essential for effective acid-base homeostasis, ensuring that our blood remains slightly alkaline, which is crucial for health and proper function.