Duplicate gene and its parental copy can subfunctionalize so that each carries out only some of the roles that the ancestral gene performed. 

Ex- a duplicate of the β-hemoglobin locus is expressed in the fetus. 

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#Unit 7. System Physiology – Animal

The initial reaction in the intrinsic system is conversion of inactive factor XII to active factor XII (XIIa).

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#Unit 7. System Physiology – Animal

kininogen and kallikrein, can be brought about 

In vitro by exposing the blood to glass

In vivo by collagen fibers underlying the endothelium

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#Unit 7. System Physiology – Animal

Active factor XII then activates  factor XI, & active factor XI activates factor IX.

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#Unit 7. System Physiology – Animal

Activated factor IX forms a complex with active factor VIII, which is activated when it is separated from von Willebrand factor.

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#Unit 7. System Physiology – Animal

The complex of IXa and VIIIa activate factor X. 

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#Id: 5193

#Unit 7. System Physiology – Animal

Phospholipids from aggregated platelets and Ca2+ are necessary for full activation of factor X.