Question

The aggregation of Hb S occurs in the ___ state, thus the formation of aggregates is most likely to occur in the ___.

a) oxy; capillaries
b) deoxy; capillaries
c) oxy; arteries
d) deoxy; arteries
e) none of the rest

Answer 1

The aggregation of hemoglobin S occurs in the deoxy state, and as oxygen is released in tissues with low oxygen pressure, aggregation is most likely in the capillaries.

Step-by-step explanation:

The aggregation of hemoglobin S (Hb S) occurs in the deoxy state, as the structure of deoxyhemoglobin is more prone to aggregation. The aggregation of hemoglobin S occurs in the deoxy state, and as oxygen is released in tissues with low oxygen pressure, aggregation is most likely in the capillaries.

Due to the S-shaped O₂-binding curve of hemoglobin and cooperativity, when in tissues where the oxygen pressure is lower, hemoglobin releases O₂, and that is when Hb S is most likely to aggregate. This aggregation causes erythrocytes to adopt a characteristic sickle shape. Therefore, the formation of aggregates is most likely to occur in the capillaries, where the oxygen concentration is lowest, affecting the blood flow through these small vessels.