Chemoreceptors present in carotid and aortic arch
are very much sensitive to

Options

A. Increase in `pCO_(2)` in arterial blood
B. Increase in `pO_(2)` in arterial blood
C. Decrease in `pO_(2)` in venous blood
D. Both (2) & (3)

Answer

To answer the question about the sensitivity of chemoreceptors present in the carotid and aortic arch, we can follow these steps:

### Step 1: Understand the Location of Chemoreceptors
Chemoreceptors are specialized cells located in the carotid bodies (at the bifurcation of the carotid arteries) and the aortic arch. They play a crucial role in monitoring blood chemistry.

**Hint:** Remember that chemoreceptors are found in specific locations related to major arteries.

### Step 2: Identify What Chemoreceptors Monitor
These chemoreceptors are sensitive to changes in the partial pressures of gases in the blood, specifically:
- Partial pressure of carbon dioxide (pCO2)
- Partial pressure of oxygen (pO2)
- Blood pH

**Hint:** Focus on the gases that are critical for respiration and how their levels can indicate the body's metabolic state.

### Step 3: Determine Sensitivity to Partial Pressures
The chemoreceptors respond to:
- An increase in the partial pressure of carbon dioxide (pCO2) in arterial blood.
- A decrease in the partial pressure of oxygen (pO2) in arterial blood.
- Changes in blood pH.

**Hint:** Think about how the body regulates breathing based on the levels of these gases.

### Step 4: Analyze the Options Provided
The question asks about the sensitivity of these chemoreceptors. The correct answer would involve recognizing that they are particularly sensitive to:
- An increase in pCO2 (which stimulates breathing).
- A decrease in pO2 (which also stimulates breathing).

**Hint:** Look for the option that includes both the increase in carbon dioxide and the decrease in oxygen levels.

### Step 5: Conclusion
Based on the understanding of the functions of these chemoreceptors, the answer is that they are very much sensitive to the increase in the partial pressure of carbon dioxide in arterial blood and the decrease in the partial pressure of oxygen in arterial blood.

**Final Answer:** Chemoreceptors present in carotid and aortic arch are very much sensitive to the increase in the partial pressure of carbon dioxide and the decrease in the partial pressure of oxygen in arterial blood.