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Question 354
Physiology → Haematology
Classification
Question
SSBAQuestion Header
Senescent erythrocytes undergo physiological breakdown within the reticuloendothelial system.
Question Stem
Which combination correctly describes the subsequent handling of erythrocyte breakdown products?
Options
A
Iron is excreted while bilirubin circulates freely to the kidney.
B
Globin is retained as the principal iron store while porphyrin is transported to the liver by erythrocytes.
C
Iron is retained for further use and bilirubin is carried by plasma protein to the liver.
D
Iron and bilirubin are both immediately excreted following erythrocyte destruction.
E
Bilirubin is retained for erythropoiesis while iron is transported by plasma protein to the liver for excretion.
Explanation
Erythrocyte breakdown occurs in the reticuloendothelial system. Haemoglobin is degraded into iron, globin and porphyrin. Iron is retained for further use, while bilirubin produced during erythrocyte breakdown is carried by plasma protein to the liver.
Option Validity
A) Iron is retained for further use rather than being discarded, and bilirubin is carried by plasma protein to the liver.
B) Haemoglobin degradation produces iron, globin and porphyrin, but globin is not described as the principal iron store and bilirubin transport is not performed by erythrocytes.
D) Iron is specifically retained for further use, so immediate excretion of both products is incorrect.
E) The described handling is reversed: iron is retained for further use, whereas bilirubin is carried by plasma protein to the liver.
Further Reading
Saxena. Textbook for MRCOG-1. Physiology - Haematology - Breakdown of Erythrocytes in the Body, p.68.