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Skip to 0 minutes and 6 secondsSo let's see what happens when we trigger the blood to clot. Let's start with whole blood. We're going to take some whole blood and place it in a tube.

Skip to 0 minutes and 25 secondsWe then take a trigger-- something that's going to activate the blood to clot.

Skip to 0 minutes and 36 secondsWe'll add that to the blood.

Skip to 0 minutes and 41 secondsWe'll give it a gentle mix. And we'll pop it in the water bath to incubate it 37 degrees to mimic body temperature. Whilst that's incubating, let's do the same to plasma. Plasma, of course, doesn't contain any cells, so this time we're going to see what happens when purely the clotting factors are involved.

Skip to 1 minute and 9 secondsWe'll take the plasma.

Skip to 1 minute and 17 secondsWe'll put some of it in a tube.

Skip to 1 minute and 28 secondsNext we'll add us a trigger.

Skip to 1 minute and 43 secondsWe'll give it a gentle mix.

Skip to 1 minute and 48 secondsAnd again we'll put it in the incubator.

Skip to 1 minute and 53 secondsSo let's think about what's happening. The trigger that we added was thrombin. Thrombin is involved in clotting through the coagulation cascade. The plasma contains the different clotting factors. They get activated when they're exposed to an injury. One clotting factor activates another which activates another which activates another. This chain reaction eventually leads to the activation of thrombin. Thrombin then converts a plasma protein called fibrinogen into fibrin. Fibrin is fibrous. It makes long strands, and it sticks all the blood together as a jelly. Let's take a look at the whole blood and see what happened.

Skip to 2 minutes and 44 secondsThere we go. The whole blood has turned to a jelly. If that were to happen inside a blood vessel, it would stop the flow of blood.

Skip to 2 minutes and 58 secondsThe plasma might take a little longer. This time we haven't got the platelets present. We've only got the clotting factors. Let's have a look.

Skip to 3 minutes and 12 secondsAnd there you go. You can see that the plasma alone. So no cells involved. Purely the clotting factors have turned the plasma into jelly. And this is what could happen inside a blood vessel.

Skip to 3 minutes and 29 secondsLet's look at the other component of blood that's involved in clotting -the platelets.

Demonstration of how blood clots: Whole blood and plasma

Let’s see what happens when we trigger either whole blood or plasma to clot with thrombin.

When you’re ready, take a look at the next demonstration where Dr Natasha Barrett will be adding thrombin to just the platelets.

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This video is from the free online course:

Heart Health: A Beginner's Guide to Cardiovascular Disease

University of Reading