Hemostasis – How blood stops after injury

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Hi,today in this blog I will give you information regarding Hemostasis.

Heme = blood
Stasis = stoppage

It simply means stoppage or arrest of blood. Ever you think why bleeding stop within few minutes after we got injured? There are series of reaction occur in our body after we got injured & It’s called Hemostasis.

There are Three stages of Hemostasis.

STAGES OF HEMOSTASIS

  1. VASOCONSTRICTION
  2. PLATELET PLUG FORMATION
  3. COAGULATION OF BLOOD
  1. VASOCONSTRICTION

    vasoconstriction in hemostasis
    Blood vessel contract

    Vasoconstriction means narrowing of blood vessel. Immediately after injury, the blood vessels constricts & decrease the amount of blood loss from the site of injury.

    If this not happen than we loss blood in more quantity. It’s natural mechanism once we got injured, blood vessels will constrict & minimise the blood loss.

    When the blood vessels are cut, the endothelium is damaged & collagen is exposed. Then role of platelet starts, platelet adhere to this collagen & get activated.

    The activated platelets secrete serotonin & other vasoconstrictor substances which cause narrowing of blood vessels. Adherence of platelets to the collagen is accelerated by Von willebrand factor. This factor act as a bridge between a specific glycoprotein present on the surface of platelet and collagen fibrils.

  2. PLATELET PLUG FORMATION

    bleeding stoppage by platelet
    platelet plug formation

    This is interesting point. Platelet plug formation means large quantity of platelet seal the rupture part of blood vessel by making plug. When we injured first vasoconstriction occur & than platelet plug formation occur.


    Once we injured, platelet get adhered to the collagen of ruptured blood vessel & secrete adenosine diphosphate (ADP) & thromboxane A2.

    This two substances attract more & more platelets & activate them. All these platelets aggregate together & form a loose temporary platelet plug or temporary hemostatic plug,  which closes the ruptured blood vessel & prevent further blood loss.
  3. COAGULATION OF BLOOD

    coagulation by 13 factors
    coagulation
    This is third step after Injury. Here we learn only superficial information about coagulation of blood. In another blog I will give A to Z information regarding this topic.

    During this process, the fibrinogen is converted into fibrin. Fibrin means material like thread and fibrin threads get attached to the loose plug. It means that platelet plug becomes strong when fibrin added. It helps in complete stoppage of bleeding.

    This way all these steps are very important for stoppage of bleeding. For coagulation of blood 13 factors needed, that I will explain in another blog.

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