In the liver, bacteria that found their way into portal circulation are destroyed by

ESIC Nursing Officer - 2019 (Shift-2)

Applied Physiology

Easy

Appeared in: ESIC Nursing Officer - 2019 (Shift-2)

Explanation

Kupffer cells are specialized macrophages that reside within the liver's sinusoids.
They are a key component of the mononuclear phagocyte system (also known as the reticuloendothelial system).
Their primary role is to perform phagocytosis, which is the process of engulfing and destroying foreign materials like bacteria, viruses, and cellular debris from the blood.
Blood from the gastrointestinal tract, rich in absorbed nutrients but also potentially containing bacteria, passes through the liver via the portal vein.
Kupffer cells act as a filter, efficiently cleansing this blood before it enters the systemic circulation, thus preventing widespread infection.

Option B: Cilia are structures associated with the respiratory and reproductive tracts, not the liver. Their function is to create movement, such as clearing mucus from the airways.
Option C: Hydrochloric acid is a powerful acid produced by the parietal cells of the stomach. Its function is to aid in protein digestion and kill ingested microbes within the stomach.
Option D: Leukocytosis is a clinical finding, specifically an elevated white blood cell count in the blood. It is a systemic sign of infection or inflammation, not a mechanism for destroying bacteria within a specific organ like the liver.

Visual 1: Diagram - A cross-section of a liver sinusoid. The visual should clearly label a hepatocyte, the sinusoidal space (lumen), and a Kupffer cell attached to the endothelial lining, shown in the act of phagocytosing a bacterium from the blood.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain The concept tested is the liver's innate immune function, specifically the role of its resident macrophages in clearing pathogens from the portal circulation as background academic context rather than a clinical decision trigger.
A nurse should understand that patients with severe liver disease, such as cirrhosis, have compromised Kupffer cell function. This makes them highly susceptible to systemic infections originating from the gut.
Monitoring for signs of infection (fever, elevated WBC count, altered mental status) is a critical nursing intervention for patients with chronic liver failure.
What if? If a patient with cirrhosis develops a fever and abdominal pain, the nurse should have a high index of suspicion for spontaneous bacterial peritonitis (SBP), a life-threatening infection that occurs due to the failure of the liver to clear gut bacteria.

How to Approach the Question

First, identify the key elements of the question: the location ('in the liver'), the substance to be destroyed ('bacteria'), and the pathway ('portal circulation').
The question asks for the specific agent of destruction within the liver.
Recall the different cell types and functions associated with the liver. The liver has many functions, including metabolic, synthetic, and defensive roles.
Evaluate each option based on this context.
Option A, Kupffer cells, are known as the macrophages of the liver. Macrophages are phagocytic cells, which fits the 'destroying bacteria' part of the question.
Options B (Cilia) and C (Hydrochloric acid) are located in different body systems (respiratory and digestive/stomach, respectively). Eliminate them as they are not in the liver.

Concept Tested & Keywords

Concept Tested: The concept tested is the liver's innate immune function, specifically the role of its resident macrophages in clearing pathogens from the portal circulation.
Stem keywords: liver, bacteria, portal circulation, destroyed
Lead-in keywords: BEST, MOST RELEVANT CLUE
Negative lead-in flag: false

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