Which of the following factors raise the `P_(50)` value and shfits the `HbO_(2)` dissociation curve to right and vice versa :
(1) Rise in `P_(CO_(2))` (2) Rise in `H^(+)` ions (Fall in pH) .
( 3) Fall in temperature (4) Fall in diphosphoglyceric acid .

Options

A. 1,2 and 3 are correct
B. 1 and 2 are correct
C. 2 and 4 are correct
D. 1 and 3 are correct

Answer

To solve the question regarding which factors raise the P50 value and shift the HbO2 dissociation curve to the right, we need to analyze each of the given options step by step.

### Step-by-Step Solution:

1. **Understanding P50 and the HbO2 Dissociation Curve**:
- The P50 value is the partial pressure of oxygen (pO2) at which hemoglobin is 50% saturated with oxygen. A higher P50 indicates a lower affinity of hemoglobin for oxygen, meaning that hemoglobin releases oxygen more readily.
- A rightward shift of the HbO2 dissociation curve indicates a decrease in hemoglobin's affinity for oxygen.

2. **Analyzing Each Factor**:
- **(1) Rise in P(CO2)**:
- An increase in the partial pressure of carbon dioxide (P(CO2)) leads to a rightward shift in the HbO2 dissociation curve. This is known as the Bohr effect, where increased CO2 levels cause hemoglobin to release oxygen more readily.
- **Conclusion**: This factor raises the P50 value and shifts the curve to the right.

- **(2) Rise in H+ ions (Fall in pH)**:
- A rise in hydrogen ions (H+) corresponds to a decrease in pH (more acidic conditions). Lower pH also causes a rightward shift in the HbO2 dissociation curve, indicating decreased affinity of hemoglobin for oxygen.
- **Conclusion**: This factor raises the P50 value and shifts the curve to the right.

- **(3) Fall in Temperature**:
- A decrease in temperature results in a leftward shift of the HbO2 dissociation curve. This means hemoglobin has a higher affinity for oxygen at lower temperatures, making it less likely to release oxygen.
- **Conclusion**: This factor does not raise the P50 value; it shifts the curve to the left.

- **(4) Fall in Diphosphoglyceric Acid (DPG)**:
- Diphosphoglyceric acid (DPG) is a metabolite that, when present in higher concentrations, shifts the HbO2 dissociation curve to the right, promoting oxygen release. A fall in DPG concentration would shift the curve to the left, indicating an increased affinity for oxygen.
- **Conclusion**: This factor does not raise the P50 value; it shifts the curve to the left.

3. **Final Evaluation**:
- The factors that raise the P50 value and shift the HbO2 dissociation curve to the right are:
- (1) Rise in P(CO2)
- (2) Rise in H+ ions (Fall in pH)
- The factors that do not raise the P50 value and shift the curve to the left are:
- (3) Fall in temperature
- (4) Fall in diphosphoglyceric acid

### Answer:
The correct factors that raise the P50 value and shift the HbO2 dissociation curve to the right are (1) Rise in P(CO2) and (2) Rise in H+ ions (Fall in pH).