Certain cells in the liver, called Kupffer cells, ingest bacteria and various kinds of debris from damaged cells. This function is most likely accomplished by :

Options

A. exocytosis
B. receptor-mediated endocytosis
C. phagocytosis
D. pinocytosis

Explanation

To solve the question regarding the function of Kupffer cells in the liver, we will analyze the processes involved in cellular ingestion and determine which one is most applicable to Kupffer cells.

### Step-by-Step Solution:

1. **Understanding the Function of Kupffer Cells**:
- Kupffer cells are specialized cells in the liver that play a crucial role in the immune response by ingesting bacteria and debris from damaged cells. This function is essential for maintaining liver health and overall immune function.

2. **Identifying the Processes**:
- The question provides four processes:
- Exocytosis
- Receptor-mediated endocytosis
- Phagocytosis
- Pinocytosis

3. **Defining Exocytosis**:
- Exocytosis is the process where vesicles within the cell fuse with the plasma membrane to release their contents outside the cell. This process is not involved in the ingestion of substances but rather in secretion.

4. **Defining Receptor-Mediated Endocytosis**:
- Receptor-mediated endocytosis is a selective process where cells take in specific substances (like nutrients or pathogens) by engulfing them in vesicles after binding to specific receptors on the cell membrane. While this is a form of endocytosis, it is not the primary method for ingesting large particles like bacteria.

5. **Defining Phagocytosis**:
- Phagocytosis is a type of endocytosis specifically for the ingestion of large particles, such as bacteria and cellular debris. In this process, the cell membrane extends around the particle and engulfs it, forming a phagosome. Kupffer cells are known to be specialized macrophages that utilize this process to clear pathogens and debris.

6. **Defining Pinocytosis**:
- Pinocytosis is the process of "cell drinking," where the cell ingests liquid and small solutes. This process is not primarily used for ingesting large particles like bacteria.

7. **Conclusion**:
- Given the definitions and functions of these processes, the most likely mechanism by which Kupffer cells ingest bacteria and debris is **phagocytosis**.

### Final Answer:
**Phagocytosis** is the process most likely accomplished by Kupffer cells to ingest bacteria and various kinds of debris from damaged cells.

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