Which cells perform phagocytic activity to remove bacteria and toxins from the blood?

MP CHO - 2022

Applied Physiology

Easy

Appeared in: MP CHO - 2022

Explanation

Kupffer cells are specialized macrophages that are part of the mononuclear phagocyte system.
They are strategically located in the lining of the liver sinusoids, which are small blood vessels within the liver.
Their primary role is to filter the blood coming from the gastrointestinal tract via the portal vein.
They perform phagocytosis to remove bacteria, endotoxins, viruses, and old red blood cells, preventing them from entering the systemic circulation.

Option A: Schistocytes are not cells but fragments of red blood cells. They are a sign of pathology (like microangiopathic hemolytic anemia) and have no phagocytic capability.
Option C: Neuroglial cells are support cells in the central nervous system (CNS). While microglia (a type of neuroglial cell) are phagocytic, their activity is confined to the brain and spinal cord, not the general bloodstream.
Option D: Merkel cells are mechanoreceptors found in the skin responsible for the sensation of light touch. They have no immune or phagocytic function.

Clinical Relevance

Nursing practice connection: Knowing Mononuclear Phagocyte System helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
The function of Kupffer cells is vital for preventing systemic infection (sepsis), especially from gut-derived bacteria. In liver diseases like cirrhosis, their number and function can be impaired, increasing the risk of infection.
These cells are also involved in clearing endotoxins. Failure to do so can contribute to the systemic inflammatory response seen in sepsis and liver failure.
What if? If a patient has severe liver cirrhosis, the reduced blood flow and impaired Kupffer cell function mean they are highly susceptible to bacteremia from normal gut flora. A nurse should be vigilant for signs of infection (fever, altered mental status) in such patients.

How to Approach the Question

First, identify the key requirements from the question: a cell type that performs 'phagocytic activity' to clean the 'blood'.
Evaluate Option A (Schistocytes): Recall that '-cyte' means cell, but 'schisto-' means split. These are cell fragments, not functional phagocytes. Eliminate.
Evaluate Option B (Kupffer cells): Recall or deduce that these are specialized cells. Their location in the liver, a major blood-filtering organ, makes them a strong candidate for filtering blood.
Evaluate Option C (Neuroglial cells): 'Neuro-' points to the nervous system. While some of these cells (microglia) are phagocytic, their domain is the brain, which is separate from the general blood circulation. Eliminate.
Evaluate Option D (Merkel cells): Recall that these are sensory cells in the skin. They are not involved in immunity. Eliminate.
Conclude that Kupffer cells are the only option that fits the criteria of being phagocytic cells that filter the general blood supply.

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