Blood dries hard because of a combination of coagulation (clotting) and the subsequent evaporation of water, leaving behind solid components.
The Process Explained
Here's a breakdown of why blood transitions from a liquid to a hard, solid state:
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Coagulation (Clotting): When blood exits the body (ex vivo), it begins to coagulate. This is a complex process involving various clotting factors and platelets.
- Fibrin Formation: A key event in coagulation is the formation of fibrin strands. These strands create a mesh-like network.
- Clot Structure: This fibrin network traps blood cells (primarily red blood cells) and other components, forming a solid clot. Think of it as a structural framework being built within the liquid blood.
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Evaporation: Once the clot is formed, the water content within the blood begins to evaporate into the surrounding air.
- Solidification: As water evaporates, the remaining solid components become more concentrated.
- Hardening: What remains are primarily red blood cells and the fibrin network, resulting in a hardened, solid mass.
In summary, the initial clotting process creates a solid structure within the blood, and the subsequent evaporation of water hardens this structure further.
