These steps of clotting are in the wrong order: fibrinogen changes to fibrin; the cascade makes…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
These steps of clotting are in the wrong order: fibrinogen changes to fibrin; the cascade makes thrombokinase; platelets and tissue release factors; prothrombin changes to thrombin; the fibrin net traps blood cells.
- Write the steps in the right order.
- Which step needs calcium ions?
- Which two plasma proteins are inactive until the injury?
Need a reminder? The key ideaShow
A clot is a net of fibrin with blood cells trapped in it. Prothrombin becomes thrombin, with Ca, and thrombin changes fibrinogen to fibrin. Tissue fluid that does not return to the capillaries is collected by the lymph vessels. Lymph is colourless, holds lymphocytes, and returns to the large veins.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) 1. Platelets and tissue release factors. 2. The cascade makes thrombokinase. 3. Prothrombin changes to thrombin. 4. Fibrinogen changes to fibrin. 5. The fibrin net traps blood cells.
Step 2. (b) The change of prothrombin to thrombin needs calcium ions.
Step 3. (c) Prothrombin and fibrinogen.
Answer: the order is injury, thrombokinase, thrombin, fibrin, clot; calcium for the thrombin step; prothrombin and fibrinogen.
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