Which of the following statements is correct regarding neural regulation of cardiac activity ?

Options

A. The cardiac centre lies in medulla oblongata of brain
B. Sympathetic nerve fibres accelerate the rate of heart beat and parasympathetic nerve fibres retard the rate of heart beat
C. Sensory fibres extend from the receptors present in the walls of aortic arch, carotid sinuses and vena cava to the cardiovascular centre in medulla oblongata
D. all of these

Answer

To determine which statements are correct regarding the neural regulation of cardiac activity, we can analyze each statement provided in the question step by step.

### Step 1: Identify the Location of the Cardiac Center
- The first statement claims that the cardiac center lies in the medulla oblongata of the brain.
- **Analysis**: This is correct. The medulla oblongata is indeed where the cardiac center is located, and it plays a crucial role in regulating heart rate.

### Step 2: Understand the Role of Sympathetic and Parasympathetic Nerves
- The second statement indicates that sympathetic nerve fibers accelerate the rate of heartbeat while parasympathetic nerve fibers retard the rate of heartbeat.
- **Analysis**: This statement is also true. The sympathetic nervous system increases heart rate and cardiac output, while the parasympathetic nervous system decreases heart rate.

### Step 3: Examine the Function of Sensory Fibers
- The third statement states that sensory fibers extend from receptors in the aortic arch, carotid sinuses, and vena cava to the cardiovascular center in the medulla oblongata.
- **Analysis**: This statement is true as well. Sensory fibers carry information from these receptors to the cardiovascular center, helping to regulate heart activity based on blood pressure and other factors.

### Conclusion
- Since all three statements are correct, the final answer is "all of these."

### Final Answer
**All of these statements are correct regarding the neural regulation of cardiac activity.**

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