Blood Clotting: shrinking scabs (Humans)

by David Turell , Tuesday, June 08, 2021, 19:11 (1052 days ago) @ David Turell

More study on why scabs shrink:

https://www.sciencedaily.com/releases/2021/06/210607202208.htm

"Blood clotting is actually a physics-based phenomenon that must occur to stem bleeding after an injury," said Wilbur A. Lam, W. Paul Bowers Research Chair in the Department of Pediatrics and the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory. "The biology is known. The biochemistry is known. But how this ultimately translates into physics is an untapped area."

And that's a problem, argues Lam and his research colleagues, since blood clotting is ultimately about "how good of a seal can the body make on this damaged blood vessel to stop bleeding, or when this goes wrong, how does the body accidentally make clots in our heart vessels or in our brain?"

The workhorses to stem bleeding are platelets -- tiny 2-micrometer cells in the blood in charge of making the initial plug. The clot that forms is called fibrin, which acts as a glue scaffold that the platelets attach to and pull against. Blood clot contraction arises when these platelets interact with the fibrin scaffold. To demonstrate the contraction, researchers embedded a 3-millimeter mold with millions of platelets and fibrin to recreate a simplified version of a blood clot.

"What we don't know is, 'How does that work?' 'What's the timing of it so all these cells work together -- do they all pull at the same time?' Those are the fundamental questions that we worked together to answer," Lam said.

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"The simulations showed that the platelets work best when they're not in total sync with each other," Lam said. "These platelets are actually pulling at different times and by doing that they're increasing the efficiency (of the clot)."

This phenomenon, dubbed by the team asynchronous mechanical amplification, is most pronounced "when we have the right concentration of the platelets corresponding to that of healthy patients," Alexeev said.

Comment: Clotting is a cascade of about 20 steps starting with platelets. we are still trying to understand it fully. Obviously the clot must be confined to the region it is needed and never massive. Activation in brain or coronary vessels is thought to be the result of leaking chemicals from cracked arteriosclerotic plaques. My question is how did unguided evolution invent such a critical but totally controlled process?