Which of the following can activate the chemosensitive area situated adjacent to the rhythm centre?

Options

A. High `CO_(2)` concentration, less hydrogen ion concentration
B. High`CO_(2)` and high hydrogen ion concentration
C. Less `CO_(2)` High `H^(+)` ion concentration
D. Less `CO_(2)` less `H^(+)` ion concentration

Answer

To solve the question "Which of the following can activate the chemosensitive area situated adjacent to the rhythm centre?", we need to analyze the options provided and understand the role of the chemosensitive area in the respiratory system.

### Step-by-Step Solution:

1. **Understanding Chemosensitive Area**: The chemosensitive area is a part of the brain that responds to changes in the chemical composition of the blood, particularly levels of carbon dioxide (CO2) and hydrogen ions (H+). It is located near the rhythm center, which controls the rate of breathing.

2. **Analyzing the Options**:
- **Option 1**: High CO2 and less hydrogen - This combination may not sufficiently stimulate the chemosensitive area because while CO2 is high, the low hydrogen ion concentration may not trigger a strong response.
- **Option 2**: High CO2 and high hydrogen - This combination is likely to activate the chemosensitive area effectively. High levels of CO2 lead to increased H+ ions (lower pH), signaling the need to increase respiration to expel CO2.
- **Option 3**: Less CO2 and high hydrogen - This scenario is unlikely to activate the chemosensitive area because low CO2 levels do not indicate a need for increased respiration, even if H+ is high.
- **Option 4**: Less CO2 and less hydrogen - This combination would not activate the chemosensitive area as both CO2 and H+ are low, indicating no need for respiratory adjustment.

3. **Conclusion**: Based on the analysis, the correct answer is **Option 2: High CO2 and high hydrogen ion concentration**. This combination activates the chemosensitive area, which then sends signals to the rhythm center to increase the rate of respiration, helping to eliminate excess CO2 and H+ from the body.