Question

1. What role does thrombin play in clot formation in a patient with a small cut?

2. Why does the physician usually order both a hemoglobin and a hematocrit test as a means of evaluating anemia?

Answer 1

1.our body itself contain a natural process to stop bleeding from minor injury, within minutes.

Let's explain it in a simple way;

A small artery is cut > the college fibers in its tissue are exposed > results in the beginning of clotting process > platelets starts to adhere to the cut edges > release of chemicals to attract more platelets > platelet plug formation > external bleeding stops.

In short there are 3 stages;

Vascular spasm

Formation of platelets plug

Coagulation

Now let's see what does the thrombin do,

As we know thrombin is a unique molecule, that can function both as a procoagulant and anticoagulant.

Procoagulant role:it activates platelets through its receptor on the platelets.

It activates coagulation factors 5 , 8 and 11 which results in burst of thrombin formation.

Activation of factor 11 prevents fibrinolysis.

Activation of factor 8 effects the cross linking of fibrin monomers to produce a firm fibrin clothes.

Then, thrombin binds to thrombomodulin, ( a receptor protein on the endothelial membrane of the blood vessel), which results in the initiation of fibrinolysis.

2. First let us see the difference between haemoglobin and hematocrit.

Haemoglobin is a protein in red blood cells, and hematocrit is a measurement of the amount of RBCs as related to total blood cell count.

Both are used to rule out aneamia.

Hematocrit test measures the proportion of blood that is made up of RBCs, WBCs, and platelets suspended in a fluid portion called plasma.

But a hemoglobin test can only determine the amount of hemoglobin in your blood.