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Question 353
Physiology → Haematology
Classification
Question
SSBAQuestion Header
A physiological change produces a substantial increase in haematocrit.
Question Stem
Which change in blood rheology is most consistent with this finding?
Options
A
Blood viscosity rises exponentially because erythrocytes account for its major component.
B
Blood viscosity rises linearly because plasma accounts for its major component.
C
Blood viscosity falls exponentially because erythrocytes become more deformable.
D
Blood viscosity remains constant because haematocrit does not influence it.
E
Blood viscosity falls because increasing erythrocyte concentration reduces resistance to flow.
Explanation
Erythrocytes are responsible for the major part of blood viscosity. Blood viscosity rises exponentially as haematocrit increases.
Option Validity
B) Erythrocytes, rather than plasma, are responsible for the major part of blood viscosity, and the stated relationship with haematocrit is exponential.
C) Increasing haematocrit raises rather than lowers blood viscosity.
D) Haematocrit has a major influence on blood viscosity; the relationship is not constant.
E) Increasing erythrocyte concentration increases blood viscosity rather than reducing it.
Further Reading
Saxena. Textbook for MRCOG-1. Physiology - Haematology - Red Blood Cells, p.67.