The heat from a hot iron will cause the immediate clotting of the blood in the vessels, and this clot is further supported by the production of a scab, or crust, over the portion seared.
Some drugs, called styptics, possess the power of contracting the walls of blood vessels and also of clotting the blood.
The object of the clotting of the blood is quite clear.
When we begin to inquire into the nature of clotting we have to determine in the first place whence the fibrin is derived.
It is very noteworthy that although the amount of fibrin formed during the clotting appears very bulky, yet the actual weight is extremely small, not more than 0.
The process of clotting is also considerably accelerated by making the blood flow in a thin stream over a wide surface.
For example, human blood kept at body temperature clots in three minutes, while if allowed to cool to room temperature the first sign of clotting may not make its appearance until eight minutes after its removal from the body.
The discovery of the origin of the thrombokinase from tissue cells explains a fact that has long been known, namely, that if in collecting blood, it is allowed to flow over cut tissues, clotting is most markedly accelerated.
Yet another very pregnant fact in connexion with clotting is that if an animal be bled rapidly and the blood collected in successive samples it is found that those collected last clot most quickly.
The power ofclotting and thus stopping haemorrhage is of essential importance, and yet this clotting must not occur within the living blood-vessels, or it would speedily result in death.
Thus in a mammal the blood clots most quickly at a temperature a little above body temperature, while if the blood be cooled quickly the clotting is considerably delayed and in the case of some animals altogether prevented.
Serum, for instance, very quickly loses its power of inducing clotting in fibrinogen solutions.
Secondly, the body has been found to possess the power of making a substance, antithrombin, which can combine with thrombin forming a substance which is quite inactive as far as clotting is concerned.
Having ascertained that the clotting is due to the action of thrombin upon fibrinogen, we now see that the next step to be explained is the origin of thrombin.
Not only does theclotting process start from the layers containing the leucocytes and platelets, but in them it also proceeds more quickly.
In certain conditions, particularly in acute exanthemata, and in the various forms of the hæmorrhagic diathesis, the clotting time is distinctly increased, or indeed clotting may remain in abeyance.
In both conditions there is a decided =increase in the clotting power of the blood=.
Herz, in which the clotting of the blood in the pipette is prevented by rendering the walls absolutely smooth by the application of cod-liver oil.
These conditions increase with the length of time after death, so that after a time a wound made on a cadaver would show very little if any clotting owing to very slight hemorrhage, and little or no clotting of the blood extravasated.
A wound in which a large artery has been divided may present very little clotting in the wound if the opening is free and the blood has mostly escaped in a jet.
The inflammation affects chiefly the walls of the vessels, and is attended with clotting of the lymph.
The cause of the clotting of blood is not yet fully understood.
Such a wound bleeds freely because the clean-cut edges do not favor the clotting of blood.
The clotting of the blood may be hastened by free access to air, by contact with roughened surfaces, or by keeping it at perfect rest.
This clotting of the blood is due to the formation in the blood, after it is withdrawn from the living body, of a substance called fibrin.
This remarkable process is known as coagulation, or the clotting of blood; and the liquid which separates from the clot is called serum.
The unfavorable effects of the want of clotting are illustrated in some persons in whom bleeding from even the slightest wounds continues till life is in danger.
The blood vessel walls are thin; the skin is delicate, clotting of the blood is usually retarded.
At the end of that period Pheola confirmed that the open sore was gone and that both areas of clotting had been repaired by Maragon's body's own restorative processes.
This was as close to a classic description of coronaryclotting as I figured I would get in nontechnical terms.
But instead of scar tissue forming to heal the open spot, clotting had taken place.
If during the time of clotting the blood is vigorously whipped with a bundle of fine rods, all the fibrin is deposited as a stringy mass on the whipper, and the remaining liquid part consists of serum plus red corpuscles.
To summarize then, the following statements may be made: (1) The immediate factor necessary to the clotting of the blood is the fibrin.
In aneurism and varix a slowing of the blood-current is present, and the intima of the diseased region is frequently in such an abnormal condition that a clotting of the blood readily takes place.
The lighter colors are due to causes which favor the precipitation of red blood-corpuscles before actual clotting takes place, or which occasion an increase of the white blood-corpuscles in fibrin.
When these materials are acted upon by a third, the fibrin ferment, clotting takes place and fibrin is formed.
Plasma and Blood Clotting Efficiency of Thromboplastic Agents in Vitro and their Stability, J.
Furthermore, any substance which tends to precipitate proteins must be injected slowly and with extreme caution, or it will produce intravascular clotting and sudden death.
This peculiar action of peptone on the clotting power of lymph may frequently be observed, even when the amount of peptone present is too small to be detected with certainty by chemical methods.
Shore finds that when small amounts of peptone are slowly injected into the blood, there is generally only a slight acceleration in the flow of lymph, but the clotting power of the lymph is affected in a remarkable manner.
But what is it that clings black and doubled across that fatal cannon, dripping and heavy, and choking the scuppers with clotting gore, and swaying to and fro with the motion of the vessel, like a bloody fleece?
There was a blue gunshot wound in her neck, from which two or three large black clotting gouts of blood were trickling.
The clotting of blood is of great physiological importance, for otherwise we might bleed to death even from a small wound.
This clotting is the result of a chemical transformation which goes on in the blood as the result of its escape from the blood vessels and its exposure to the outside.
