The blood groups in individuals are different due to the specific:

AIIMS Jodhpur SNO-2023

Medical & Surgical Nursing

Easy

Appeared in: AIIMS Jodhpur SNO-2023

Explanation

Blood groups are classified based on the presence or absence of inherited antigenic substances on the surface of red blood cells (RBCs).
These surface molecules are known as antigens or agglutinogens.
The most clinically important blood group systems, ABO and Rhesus (Rh), are both defined by specific antigens on the RBC membrane.
For example, in the ABO system, type A blood has A antigens, type B has B antigens, type AB has both, and type O has neither.

Option A: White blood cells (WBCs) have surface antigens, but these are Human Leukocyte Antigens (HLA), not the antigens used for standard blood grouping.
Option B: Antibodies are proteins that circulate in the blood plasma; they are not attached to the surface of WBCs to determine blood type.
Option D: Antibodies (agglutinins) are found in the blood plasma, not on the surface of red blood cells. Their presence is reciprocal to the antigens on the RBCs.

Visual 1: Diagram: Illustrating the four main blood types (A, B, AB, O) showing the specific antigens on the surface of the red blood cells and the corresponding antibodies in the plasma.
Visual 2: Infographic: Comparing the role of RBC antigens (for blood typing) and WBC antigens (HLA for tissue typing).

Clinical Relevance

Nursing practice connection: Knowing Basis of Blood Grouping (ABO System) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Blood transfusion safety is paramount. Matching a patient's blood type (based on RBC antigens) with donor blood is essential to prevent a life-threatening hemolytic transfusion reaction, where the recipient's antibodies attack the donor's RBCs.
In pregnancy, Rh incompatibility is a major concern. If an Rh-negative mother carries an Rh-positive fetus, she can develop antibodies that may harm subsequent Rh-positive babies. This is managed with Rho(D) immune globulin.
What if? If a person with Type O blood (no antigens, anti-A and anti-B antibodies) is incorrectly transfused with Type A blood, their anti-A antibodies will immediately attack and destroy the transfused RBCs, causing a severe, potentially fatal, transfusion reaction.

How to Approach the Question

First, identify the core of the question, which is asking for the fundamental biological marker that differentiates blood groups.
Recall the basic principles of immunology and hematology. Differentiate between an antigen (a molecule on a cell surface that triggers an immune response) and an antibody (a protein in the plasma that responds to an antigen).
Consider the cells involved. Blood grouping specifically relates to red blood cells (erythrocytes), while tissue typing for transplants involves white blood cells (leukocytes).
Evaluate each option based on these principles: Blood types are determined by antigens (markers) on the surface of red blood cells.
This systematic elimination leads to the correct option by correctly associating antigens with RBCs for blood grouping.

Concept Tested & Keywords

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