Cardiac sphicnter protects back flow of

Options

A. Food into esophagus
B. Blood into heart
C. Blood into auricle
D. Blood into vena cava

Answer

**Step-by-Step Solution:**

1. **Understanding the Cardiac Sphincter**: The cardiac sphincter, also known as the lower esophageal sphincter, is a ring of smooth muscle located at the junction of the esophagus and the stomach.

2. **Function of the Cardiac Sphincter**: Its primary function is to prevent the backflow (reflux) of contents from the stomach into the esophagus. This is crucial because the stomach contains acidic gastric juices that can damage the esophageal lining.

3. **Analyzing the Options**:
- **Option A: Food into esophagus** - This is correct. The cardiac sphincter prevents the backflow of food from the stomach into the esophagus.
- **Option B: Blood into heart** - This is incorrect. The cardiac sphincter does not regulate blood flow.
- **Option C: Blood into auricle** - This is also incorrect. The cardiac sphincter does not have any role in blood circulation.
- **Option D: Blood into vena cava** - This is incorrect as well. The cardiac sphincter does not prevent blood from flowing into the vena cava.

4. **Conclusion**: Based on the function of the cardiac sphincter and the analysis of the options, the correct answer is **Option A: food into esophagus**.

**Final Answer**: The cardiac sphincter protects against the backflow of **food into the esophagus**.

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