The correct option for the pH level of blood in a normal person is Option 3: 7.35 – 7.45.

The pH scale measures the acidity or alkalinity of a solution, and it ranges from 0 to 14. A pH of 7 is considered neutral, below 7 is acidic, and above 7 is alkaline or basic. The pH level of blood is tightly regulated by the body, and maintaining it within a narrow range is crucial for proper physiological functioning.

The pH level of blood is slightly alkaline, which helps in maintaining the proper functioning of enzymes and other biological processes. The normal pH range for arterial blood is 7.35 to 7.45. Arterial blood is the oxygen-rich blood that is pumped by the heart to various organs and tissues in the body. It plays a crucial role in delivering oxygen and nutrients while removing waste products.

Several factors contribute to the regulation of blood pH. The main regulators are the respiratory system and the kidneys. The respiratory system controls the levels of carbon dioxide (CO2) through the exchange of gases in the lungs. CO2 is an acidic waste product that forms when cells produce energy. By adjusting the rate and depth of breathing, the body can regulate the elimination of CO2 and maintain the pH balance.

The kidneys also play a significant role in maintaining the blood pH by regulating the levels of bicarbonate ions (HCO3-) and hydrogen ions (H+). The kidneys can excrete excess acids or reabsorb bicarbonate ions to balance the pH levels.

Deviation from the normal pH range can have significant health consequences. Acidosis occurs when the blood pH drops below 7.35, which can be caused by conditions such as diabetes, kidney disease, or lung diseases. Alkalosis, on the other hand, happens when the blood pH rises above 7.45, and it can be caused by hyperventilation or certain medications.

In summary, the pH level of blood in a normal person falls within the range of 7.35 to 7.45. This range is tightly regulated by the body through various mechanisms to ensure proper physiological functioning. Deviations from this range can lead to health issues, highlighting the importance of maintaining blood pH within the normal range.