Injury to the medulla oblongata in humans is not likely to affect:

Options

A. Gastric secretion
B. Cariac movements
C. Unconditioned reflex
D. Controlled respiration

Answer

To solve the question regarding the effects of injury to the medulla oblongata in humans, we need to analyze the functions of the medulla oblongata and determine which of the given options is least likely to be affected by such an injury.

### Step-by-Step Solution:

1. **Understanding the Medulla Oblongata**:
- The medulla oblongata is a part of the hindbrain and is responsible for several autonomic functions. It controls vital functions such as respiration, heart rate, and reflex actions.

2. **Analyzing Each Option**:
- **Option A: Gastric Secretion**:
- The medulla oblongata has some influence on gastric secretion through the autonomic nervous system, particularly the parasympathetic division. Therefore, this function could be affected by an injury.

- **Option B: Cardiac Movement**:
- The medulla oblongata plays a crucial role in regulating heart rate and blood pressure through the cardiovascular center. An injury here would likely impact cardiac movement.

- **Option C: Unconditional Reflex**:
- Unconditional reflexes (also known as innate reflexes) are primarily controlled by the spinal cord and do not necessarily involve the medulla oblongata. Therefore, an injury to the medulla is not likely to affect these reflexes.

- **Option D: Controlled Respiration**:
- The medulla oblongata is essential for the control of respiration. An injury to this area would significantly affect the ability to regulate breathing.

3. **Conclusion**:
- Based on the analysis, the function that is least likely to be affected by an injury to the medulla oblongata is **Option C: Unconditional Reflex**.

### Final Answer:
**C: Unconditional Reflex**