Body Fluids and Circulation

Thromboplastin (thrombokinase) is released from injured tissues and platelets and initiates the clotting process.
In the presence of $Ca^{2+}$, thromboplastin activates the conversion of inactive prothrombin into active thrombin.
Thrombin converts the soluble plasma protein fibrinogen into insoluble fibrin threads, which form a network that traps blood cells and forms the clot.
So if thromboplastin is introduced into the blood stream, it will start this sequence and cause coagulation at the site of its introduction.
Fibrinogen and prothrombin are already present in normal blood in the inactive state, so adding them does not start clotting.
Heparin is an anticoagulant that prevents clotting.
So the substance is thromboplastin.

Glucose-6-phosphate dehydrogenase (G6PD) is the first enzyme of the pentose phosphate pathway, which produces NADPH.
In red blood cells this pathway is the only source of NADPH, which keeps glutathione in its reduced form; reduced glutathione protects the cells against damage by oxidising agents.
In G6PD deficiency (an X-linked recessive disorder) the RBCs cannot protect themselves from oxidative stress.
On exposure to certain drugs (such as primaquine and sulphonamides), infections or fava beans, the haemoglobin and membranes of the RBCs are damaged and the cells burst.
This haemolysis of red blood cells causes haemolytic anaemia.
So G6PD deficiency is associated with the haemolysis of RBCs.