Coagulation Cascade SIMPLEST EXPLANATION !! The Extrinsic and Intrinsic Pathway of HEMOSTASIS

Coagulation Cascade SIMPLEST EXPLANATION !! The Extrinsic and Intrinsic Pathway of HEMOSTASIS


in this video we are going to talk about the
coagulation cascade. before beginning make sure you have seen the
first part of the video which explains the clotting factors in detail
i will leave a link to that video on the screen right now.
be sure to watch that video for a better understanding of this topic
lets first have an overview regarding what happens in the coagulation cascade
so we have an intrinsic pathway and we have an extrinsic pathway
they both eventually lead to the formation of prothrombin activator which is actually
activated factor 10 once prothrombin activator is activated it
in the prescence of calcium ions it converts prothrombin into thrombin
and when sufficient quantity of thrombin is fromed in the blood it leads to the conversion
of fibrinogen into fibrin but initially these fibrin are just monomers
and they cannot form a stable clot so in the prescence of calcium ions the fibrin stabilixzing
factor which is acyually the activated factor 13 it acts on them and converts them into
fibrin polymers by formation of covalent bonds in the fibrin
monomers and they eventually lead to the formation
of aclot by attracting lots of platelets lots of phospholipids that adheres of them and
forms a stable clot which plugs the bleeding site and leads to hemostasis lets first talk about the extrinsic pathway
so the extrinsic pathway begins with any factor which causes tissue trauma
now this trauma can be a a trauma to the vascular wall itself or it can be a trauma to the esxtra
vascular tisse and this causes the realease of tissue factor also known as tissue thromboplastin
. now this tissue factor causes the conversion
of factor no. 7 to activated factor no. 7 and then the tisse factor combines with the
activated factor 7 in the presence of calcium ions causes the conversion of factor no. 10
to activated factor no. 10 and then the factor no. 10 which is activated in the presence
of calcium ions and factor no. 5 forms the prothrombin activator
and rest events are the same that is the prothrombin activator causes the conversion of prothrombin
into thrombin now lets talk abouot the intrinsic pathway
intrinsic pathway begins with any factor which causes trauma to the blood cells directly
or causes the xposure of blood cells to collagen this causes the activation of factor no. 12
so when the factor no. 12 is activated it acts upon the factor no. 11 and causes its
ctivation that is 11 a . and this 11 a factor acts upon the factor
no. 9 and forms the factor no. 9 a and these reactions require some co factors
like the high molecular weight kininogens and calcium ions
and then the factor no.9 which is activated in the presence of factor no. 8 a
which is derived from factor 8 it combines with the calcium ions
and causes the activation of factor 10 and then the events are almost same as that
of the extrinsic pathway that is combination of activated factor 10
to calcium ions and factor 5 and formation of a prothrombin activator and the prothrombin
activator subsequently acting on the prothrombin and formation of thrombin
so to summarize what happens in the coagulation cascade
we have the intrisic pathway and the extrinsic pathway
they both ultimately lead to the formation of a prothrombin activator
that is activated facotor 10 and this causes the formation of thrombin from prothrombin
and thrombin acts on fibrinogen and froms the fibrin monomers but these monomers are
not stable and they cannot from a clot so the fibrin stabilizing factor which the factor
no. 13 it acts upon the fibrin monomers and froms lots of covalent bonds between the fibrin
monomers and this leads to formation of fibrin mesh
and this mesh attracts platelets phospholipids and forms a stable blood clot
which causes hemostasis. so this was pretty much all about the coagulation
cascade i hope you find this video informative
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100 Replies to “Coagulation Cascade SIMPLEST EXPLANATION !! The Extrinsic and Intrinsic Pathway of HEMOSTASIS”

  1. in first few minutes u mentioned PROTHROMBIN ACTIVATOR is same as the FACTOR X. Then it was mentioned that the FACTOR Xa along with Va activates prothrombin activator???

  2. These two videos are the best when watched together. Thanks so much, please keep making videos for med students💚

  3. Two questions.

    1. How does extravascular tissue damage trigger coagulation? If there is no violation, then there would be no means for platelets to exit the vessel and enter the tissue spaces, right?

    2. Regarding the trauma to blood vessels – could you expand a little? Also how is it that blood cells would be exposed to collagen? If this is intrinsic, and not extrinsic, erythrocytes shouldn't be in contact with extravascular collagen fibres in the surrounding tissues.

    So is it the case then that there is some intravascular exposure that I'm unaware of?

    I would very much appreciate any answers and especially any references that you could provide for further reading.

    Cheers

  4. I normally go to medsimplified videos on youtube. Great explanations you have over here. Thank you so much for these videos.

  5. Einstein once said : If you cant explain it to a year old,then probably you dont understand it neither. Thanks for revealing the beauty of physiology. I admire your way of teaching.

  6. I like it. This is how we really wanted to learn. Make and Upload another vides as more convenient as this. So that we can more appreciate your videos.

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