The blood cells that destroy invading bacteria or virus :

Appeared in: IGNOU PB Bsc Entrance-2023

Explanation

Lymphocytes are a type of white blood cell (leukocyte) that plays a central role in the immune system, as stated in medical textbooks.
They are responsible for recognizing and eliminating specific pathogens, such as bacteria and viruses.
This category includes B cells (which produce antibodies), T cells (which kill infected cells and regulate immunity), and Natural Killer (NK) cells (which kill virally infected and tumor cells).

Option A: Melanocytes are cells found in the skin's epidermis responsible for producing melanin, the pigment that gives skin its color. They are not blood cells and have no immune function.
Option C: Erythrocytes, or red blood cells, are responsible for transporting oxygen from the lungs to the body's tissues and carrying carbon dioxide back. They lack a nucleus and organelles needed for immune functions.
Option D: Thrombocytes, or platelets, are small, irregular cell fragments that are crucial for blood clotting and wound healing. They stop bleeding by forming plugs in injured blood vessels.

Clinical Relevance

Nursing practice connection: Knowing Functions of different blood cell types helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
A complete blood count (CBC) with differential is a common lab test that measures the number of different blood cells, including lymphocytes. An elevated lymphocyte count (lymphocytosis) can indicate a viral infection, while a low count (lymphopenia) can suggest an immune deficiency.
Understanding the function of each blood cell is critical for interpreting lab results and diagnosing conditions ranging from anemia (low erythrocytes) to infections and leukemia (abnormal leukocytes).
What if the question asked for the blood cell that is the first responder to bacterial infections? The answer would be Neutrophils, which are phagocytic white blood cells and the most abundant type of leukocyte.

How to Approach the Question

First, identify the key action in the question: 'destroy invading bacteria or virus'. This points to an immune function.
Next, review the options and recall the primary function of each cell type.
Melanocytes are skin pigment cells, so they can be eliminated.
Erythrocytes are red blood cells for oxygen transport, so they can be eliminated.
Thrombocytes are platelets for clotting, so they can be eliminated.
This leaves Lymphocytes, which are known to be a key component of the immune system responsible for fighting pathogens.

Concept Tested & Keywords

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E6 Nursing Brunner Adult Health 3SA Vol 1 Part 3 p. 113-115

E6 Medicine Davidson Principles Practice 24e p. 937-939

E6 Anatomy Applied Ashalatha 4e p. 154-156

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