Which of the following statements are CORRECT ?
I. A specialized center present in the medulla region of the brain called respiratory rhythm center is primarily responsible for the regulation of respiration.
II. A Chemosensitive area is situated adjacent to the rhythm which is highly sensitive to `O_2,CO_2` and hydrogen ions .
III . Receptors associated with aortic arch and carotid artery also can recognize changes in `CO_2 and H^+` concentration and send necessary signals to the rhythm center for remedial actions.
IV The neural signal from the pneumatic center can increase the duration of inspiration and thereby alter the respiratory rate .

Options

A. I,III and IV
B. II,III and IV
C. I and III
D. I and II

Answer

To determine which statements are correct regarding the regulation of respiration, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement I**: "A specialized center present in the medulla region of the brain called respiratory rhythm center is primarily responsible for the regulation of respiration."
- **Analysis**: This statement is correct. The respiratory rhythm center, located in the medulla oblongata, is indeed responsible for controlling the rhythm of breathing.

2. **Statement II**: "A Chemosensitive area is situated adjacent to the rhythm which is highly sensitive to O2, CO2, and hydrogen ions."
- **Analysis**: This statement is incorrect. The chemosensitive area is primarily sensitive to carbon dioxide (CO2) and hydrogen ions (H+), but not to oxygen (O2) in the same way. Oxygen levels are monitored by peripheral chemoreceptors, not the chemosensitive area adjacent to the rhythm center.

3. **Statement III**: "Receptors associated with aortic arch and carotid artery also can recognize changes in CO2 and H+ concentration and send necessary signals to the rhythm center for remedial actions."
- **Analysis**: This statement is correct. The receptors in the aortic arch and carotid arteries (peripheral chemoreceptors) do detect changes in CO2 and H+ concentrations and send signals to the respiratory centers in the brain to adjust breathing accordingly.

4. **Statement IV**: "The neural signal from the pneumatic center can increase the duration of inspiration and thereby alter the respiratory rate."
- **Analysis**: This statement is incorrect. The pneumatic center actually helps to inhibit inspiration, thereby reducing the duration of inspiration and increasing the respiratory rate.

### Conclusion:
- **Correct Statements**: I and III are correct.
- **Incorrect Statements**: II and IV are incorrect.

### Final Answer:
The correct statements are I and III.

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