Which o fthe following factors raise the `P_(50)` value and shifts the `HbO_(2)` dissociaton curve to right ?

Options

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

Answer

To determine which factors raise the `P_(50)` value and shift the `HbO_(2)` dissociation curve to the right, we need to understand the factors that affect hemoglobin's affinity for oxygen. The `P_(50)` value is the partial pressure of oxygen at which hemoglobin is 50% saturated with oxygen. A higher `P_(50)` value indicates a lower affinity for oxygen, which corresponds to a rightward shift in the dissociation curve.

### Step-by-Step Solution:

1. **Understanding the Oxygen-Hemoglobin Dissociation Curve**:
- The oxygen binding to hemoglobin is represented by a sigmoid (S-shaped) curve. This curve indicates cooperative binding, meaning that as one oxygen molecule binds to hemoglobin, it facilitates the binding of additional oxygen molecules.

**Hint**: Remember that the shape of the curve indicates how easily hemoglobin can bind to oxygen.

2. **Factors Affecting Hemoglobin Affinity**:
- Several factors can influence the affinity of hemoglobin for oxygen, including pH, carbon dioxide concentration (pCO2), temperature, and the presence of certain metabolites like 2,3-bisphosphoglycerate (2,3-BPG).

**Hint**: Focus on the physiological factors that can change hemoglobin's affinity for oxygen.

3. **Bohr Effect**:
- The Bohr effect describes how a decrease in pH (increase in H+ concentration) and an increase in pCO2 lower the affinity of hemoglobin for oxygen, causing a rightward shift in the dissociation curve. This means that a higher `pO2` is required for hemoglobin to bind to the same amount of oxygen.

**Hint**: Recall that lower pH and higher pCO2 decrease hemoglobin's affinity for oxygen.

4. **Temperature Effects**:
- An increase in temperature also decreases hemoglobin's affinity for oxygen, leading to a rightward shift in the curve. This is important during exercise when body temperature rises.

**Hint**: Consider how physical activity and temperature changes can affect oxygen delivery.

5. **Identifying the Correct Factors**:
- From the discussion, we can conclude that:
- A **lower pH** (higher H+ concentration) shifts the curve to the right.
- A **higher pCO2** also shifts the curve to the right.
- An **increase in temperature** shifts the curve to the right.
- Conversely, an increase in 2,3-BPG would also lower the affinity and shift the curve to the right.

**Hint**: Look for conditions that lead to decreased affinity for oxygen, which will raise the `P_(50)` value.

6. **Conclusion**:
- The factors that raise the `P_(50)` value and shift the `HbO_(2)` dissociation curve to the right are:
- Increased pCO2
- Decreased pH (increased H+ concentration)
- Increased temperature

Therefore, the correct answer to the question is the combination of these factors.

**Final Answer**: The factors that raise the `P_(50)` value and shift the `HbO_(2)` dissociation curve to the right are an increase in pCO2 and a decrease in pH (increase in H+ concentration).