|This article is of interest to the following WikiProjects:|
- 1 Resident Evil
- 2 A question
- 3 Exposure to air
- 4 Term
- 5 title
- 6 disclaimers
- 7 Chromosomes
- 8 Coagulation cascade vs cell-mediated model
- 9 Thrombelastography
- 10 Coagulation cascade
- 11 Introduction
- 12 Spelling
- 13 Primary hemostasis
- 14 Diagram
- 15 Historical source
- 16 Too technical for laymen
- 17 Copyedit
- 18 Clusters
- 19 Photo
- 20 Plagiarism
- 21 Time
- 22 it requires modification
- 23 vWF
- 24 Page name?
in the movie Resident Evil (2002), Matt Adison points out that a woman's blood has coagulated, pointing out it's impossible because blood only coagulates after death. One; blood coagulates all the time, not only after death. And two, how can you tell by looking at blood to see if it coagulated? —Preceding unsigned comment added by Blindy me (talk • contribs) 23:33, 15 September 2008 (UTC)
Exposure to air
As a non-biologist, what this article doesn't tell me is how exposure to air makes platelets stick together, which is perhaps what coagulation is all about.
What it needs is something like "when factor blah on the surface of the platelet or in the blood comes into contact with air/oxygen/nitrogen/knives/blunt_objects is it suppressed/enhanced/confused/enlightened which triggers the cycle". I'm guessing that all these factors are also expressed on the surface of the platelet? Or are they inside? A chatty intro to the subject before the factor X does whatever to factor XI would help. - (unsigned)
- We recognize the problem that different audiences require different presentations. We haven't quite worked out if separate articles are needed or if it can all be included in one place.
- In the meantime, though: exposure to air doesn't make platelets stick together, exposure to collagen does. Collagen is found in the connective tissue that is found outside of blood vessels.
- Primary clot formation has three basic steps
- Platelets aren't normally exposed to collagen: when they are exposed to it (for example, when a blood vessel is cut), they stick to it: that's platelet adhesion
- The platelets then secrete the chemicals they store: that's granule release
- The granule's contents enable fibrinogen to link between platelets (platelet aggregation)
- That's primary hemostasis. Coagulation (secondary hemostasis) happens after that, as a way of firming up the initial clot through the formation of thrombin, which converts fibrinogen to fibrin. - Nunh-huh 02:19, 26 May 2004 (UTC)
- Nunh-huh answered the question well but I think that one point to clarify to a lay-person is that you can't get to air without passing by the connective tissue (CT) that surrounds all blood vessels. Because a major component of CT is collagen then collagen will be exposed upon any blood vessel rupture, even those that are open to "air". As you can see, you must first cross collage to get to air. In the case of a gapping wound that is wide open, the bleeding cannot stop itself and stitches or some other controlling factor is needed to seal off the exit point and give the exposed collagen a chance to induce hemostasis.Orlandoturner (talk) 20:59, 8 May 2008 (UTC)
- to the OP, you can also imagine that a lot of internal bleeding occurs where there is little to no "air" and people don't die from bruises and such, further implicating collagen. Anyway, I thought the article was well written. I especially liked how in the intro it explains how the platelet activation and coagulation pathways intertwine. But here's some food for thought: how does blood stasis lead to coagulation? For example, it's known that blood stasis is one of the factors that can lead to thrombus formation, hence the whole DVT on the airplane thing. Assuming that my blood vessels aren't being damaged while I'm just sitting down, it would seem that blood seems to want to clot by default, perhaps due to collagen particles being deposited in the deep veins? -- Bubbachuck (talk) 20:41, 12 April 2009 (UTC)
I know the wikipedia's not a dictionary; but I still feel it's important not to suggest to a user who stumbles onto the page that coagulation is a technical term. Clearly it is in a medical context, but it's also just a plain old word in the English language. Hence the little disclaimer I added at the top of the page. I also specified that the article is about human blood, since it makes reference to specific clotting factors, genetic diseases, etc. I assume that the coagulation of blood in other animals follows a similar process — indeed, I'd bet my shirt on it — but I feel a little weird adding my own uninformed assumptions to a medical article so I'll just put this sentence here, which was once the last sentence of my disclaimer: The blood of other animals clots in similar ways. Please, somebody who can actually say this based on personal knowledge, add it back in again! Doops 21:43, 30 May 2004
it appears to me that this page is improperly titled. i suggest:
1) we make coagulation a disambig page with links to human blood coag as well as other types of coag like eggs + chinese food.
2) we move the material on this page to Coagulation of human blood.
Thoughts? Ungtss 16:42, 20 Apr 2005 (UTC)
- I'm more in favour of coagulation (disambiguation). Blood coagulation is by far the most important form. JFW | T@lk 23:11, 20 Apr 2005 (UTC)
- apologies. since the bold title in the intro already said coagulation of human blood, i thought it was an intuitive move. sorry i jumped the gun. Ungtss 23:40, 20 Apr 2005 (UTC)
- It certainly seems less intuitive to me than the other, but the present arrangement is clearly very important to you, and it certainly does no harm -- I'll agree. Ungtss 01:17, 21 Apr 2005 (UTC)
- Well, I do not agree. I think that the coagulation article should discuss the concept of coagulation and then there should be more specific articles for eg. coagulation of human blood, water purifying, egg-cooking and other examples. Now there is actually no article on the concept of coagulation, which I think should definitely be included in any encyclopedia. If there is 100s of links affected then let's change them.--Qtea 21:40, 10 February 2007 (UTC)
Do you have material that would be useful in a general way? Coagulation is not a phase in the way freezing or thawing is. It means widely different things in widely different contexts. Show us how you would generalise the entire concept of coagulation. JFW | T@lk 16:16, 27 July 2007 (UTC)
I haven't been actively involved with Wikipedia logistics in a while, but what is the criteria between showing a disambig page first vs. going to a default article? Is blood coagulation being "the most important form" one of the criteria? In that case, it would seem that Cricket should direct to the insect, which I'm pretty sure is indispensable to the ecosystem, rather than the sport. -- Bubbachuck (talk) 20:46, 12 April 2009 (UTC)
Since the moving of this article from the specific "coagulation of human blood" to the general "coagulation" it has become important to include disclaimers and disambiguations. Two thoughts about these:
- I was under the impression that all editorial comments which are not really part of an article but serve as aids-to-readers are italicized. That would seem sensible, certainly.
- Mammals aren't the only blooded animals! Birds have blood — how do they clot? etc. You have to cover every possibility, leaving no cracks for a confused reader to slip through.
(In general, indeed, this article — like so many scientific ones — assumes too much of the reader.) Doops 16:48, 21 Apr 2005 (UTC)
- I agree. ideally, we'd have articles on the coagulation of many types of animal blood. in the meantime, it's important to clarify in the note at the top, in italics, that is article, tho titled coagulation generally, is quite counterintuitively only about one very specific type of coagulation, and only one type of blood coagulation. Ungtss 18:29, 21 Apr 2005 (UTC)
Most studies on coagulation of blood have been done in humans and small rodents. It is a highly conserved process in evolution, so there is a lot to be said about coagulation in other species. I suspect we'll need a separate paragraph on it, which identifies the exceptions rather than the similarities. JFW | T@lk 16:16, 27 July 2007 (UTC)
Would be great to have written which chromosomes code for different factors. --Eleassar777 13:49, 19 May 2005 (UTC)
- Follow the links, Eleassar. When I wrote all the articles, I put the chromosome data there. If I have the time I may do it myself. JFW | T@lk 20:13, 19 May 2005 (UTC)
Coagulation cascade vs cell-mediated model
as i recently have learned, the coagulation cascade is somewhat misleading in how the reactions occour. also im under the impression that the current scientist are commonly accepting this model instead of the old one from 1964.
more specifically, the order in which these reactions occour. i suggest interested ppl to read reviews by M hoffman and som from Nature to get a detailed description of how it works:
Anyway the coagulation cascade fails to explain why for instance people with FXII deficiency do not have any bleeding disorders whatsoever, although it lies at the top of the cascade. Furthermore, the cascade fails to explain why FVIII from the intrinsic pathway causes heavy bleading disorders when it clearly shows that Thrombin can be produced from the extrinsic pathway alone.
shortly the cell mediated model is divided in three parts: initiation, amplification and propagation.
- Well, there are various theories about the relative importance of both systems. The system is so immensely complex that an overview is hard to present anyway. JFW | T@lk 23:18, 1 November 2005 (UTC)
hmmm... so does that mean that the cell-mediated model is not fully accepted among scientists, or that the system is not yet fully understood? because from what i have read the new model makes complete sense. anyway, yeah the system is complex. still, if the other one is more correct it ought to be changed?
- I wasn't suggesting any such thing. I'm just concerned that the Hoffman et al view will suddenly be touted as the new gospel with no consideration for previous views. The coagulation cascade is much better understood that the cellular component; one learns new things about the role of platelets and endothelium vis a vis the coagulation cascade on a daily basis. Specifically the role of the extrinsic part is setting the "rate" of thrombin generation and the tissue factor part to initiate actual coagulative events is quite fascinating.
- You are fully in your right to summarise the Hoffman et al paradigm in a short section. I have no access to the journal, so I would personally prefer something that is more accessible. JFW | T@lk 21:43, 3 November 2005 (UTC)
Don't know if anyone cares but as of 2010 all medical students at one of the large London medical schools are taught that the old intrinsic/extrinsic model is an old fallacy and are only being taught the cell based model. —Preceding unsigned comment added by 184.108.40.206 (talk) 10:14, 25 July 2010 (UTC)
- "Cell-based model"? Please do me a favour and find out which sources form the basis of your lecturers' model. I'm very keen to get this page up-to-date. JFW | T@lk 17:36, 25 July 2010 (UTC)
- PMID 14760207 is the paper in question, and I shall need to look at it. JFW | T@lk 20:59, 25 July 2010 (UTC)
I just wikified and largely rewrote a stub article on thromboelastography (and learned a lot in the process), but I'm not sure where in this article it should be linked. Could those in the know please review my work, and add useful links to it from other articles? — Catherine\talk 18:44, 7 December 2005 (UTC)
Playing the random 10 articles game, I found this article. It appears to be nothing more than a copy and paste from Clotting_cascade#The_coagulation_cascade (ie, this page). It would be great if someone could be bold and decide whether the section merits its own page. If so, the material should probably be removed from this page with a link to that one, and it should be seriously wikified and contextified.
If not, the other page should be replaced with a redirect to this one (and there is one page linking to that page - please fix its link).
Thanks, pfctdayelise 14:12, 8 December 2005 (UTC)
- Please review Wikipedia:Redirect. You've traveled over a redirect to the same page. JFW | T@lk 03:05, 29 January 2006 (UTC)
I don't think the sentence "The use of adsorbent chemicals, such as zeolite, and other haemostatic agents is also being explored for use in sealing severe injuries quickly." really belongs in the intro. I am not sure if it even belongs to this page at all. Maybe we need a page Treatments for severe bleeding or something along those lines. I didn't make the edit since I didn't want to just remove the info without having anywhere else to put it.
Thanks, Azad 15:05, 28 January 2006 (UTC)
The coagulation cascade of secondary hemostasis has two pathways, the Contact Activation pathway (formally known as the Intrinsic Pathway) and the Tissue Factor pathway (formally known as the Extrinsic pathway) that lead to fibrin formation.
Do you mean formally as in 'the Contact Activation pathway is not an official term, it is informal', or actually 'formerly' as in 'used to be called'? Adam
- I have Biochemistry now in Med School and I asked my BioChem professor regarding this sentence "contact activation pathway (formerly known as the intrinsic pathway), and the tissue factor pathway (formerly known as the extrinsic pathway)". He said that the "contact activation pathway" and "tissue factor pathway" are not correct and refer to something else entirely. Also the 2009 edition of Lehninger Principles of Biochemistry (ISBN: 071677108X) still refer to the pathways as intrinsic pathway and extrinisic pathway. Could we get an expert here to look into this, because this may be either (1) vandalism or (2)a mistake, since there is no reference after the above statement in the wiki article. Meishern (talk) 11:05, 29 April 2009 (UTC)
Hi ppl , just as a quick comment, i though it was spelt HOMEOSTASIS not haemostasis.
- Not really. Haemostasis or hemostasis is the stasis (arresting flow) of haemos (blood). Homeostasis is homeo (equal). JFW | T@lk 20:55, 22 March 2006 (UTC)
- To clarify the above comment, homeostasis is indeed not the same as hemostasis (or its equivalent "haemostasis"). Hemostasis is the stopping of the flow of blood. The use of the word is not only appropriate when speaking about coagulation/clotting, one can also accomplish hemostasis by suturing, bandaging, or compression. The spelling "haemostasis" is an older variant, probably more common in British parlance, similar to "orthopaedic" for orthopedic or "paediatrics" for pediatrics. Homeostasis, however, has nothing to do with blood. It refers to the tendency of a biological system to maintain internal metabolic and functional balance. "Homeo-" does not refer to blood; it refers to equality, or sameness. For example: homosexual is "same sex."
I know that this page is about coagulation, which is not exactly the same thing as hemostasis, but the article does describe primary and secondary hemostasis (of which the coagulation cascade is a huge part). In that description, platelet aggregation is listed as the first step in primary hemostasis, but I was under the impression that vasoconstriction happens before that... LanceVictor 16:39, 25 March 2006 (UTC)
- I learnt it that way in medical school, but would not change the article without a WP:RS. JFW | T@lk 16:02, 12 September 2006 (UTC)
- Pick up any anatomy and physiology textbook and in the blood section it will say vasoconstriction is the first step of coagulation. --220.127.116.11 (talk) 02:31, 5 February 2009 (UTC)
I think the diagram is misleading - in the coag cascade, Factor XIIa activates Factor XI to Factor XIa. If the arrows were flipped so that the middle curved bit was at Factor XIIa and the beginning of the arrow was at FXI and the end at FXIa, this would make more sense. Also this diagram is confusing as it mixes what happens in a test tube and what occurs in vivo. In vivo FXII is not part of coagulation, but is involved in fibrinolysis - the process by which the clot is removed.18.104.22.168 17:08, 5 July 2006 (UTC)CJ
- Its effects on fibrinolysis are about as limited as those on coagulation - in vitro more than in vitro. It is probably more of a participant in the kinin-kallikrein system. Hageman died of a pulmonary embolism! (Source: Giangrande.) JFW | T@lk 16:02, 12 September 2006 (UTC)
Yes, the diagram is drawn improperly. The activated factors should be placed near the middle of the arrow representing the next step in the cascade. AAMiller 07:51, 6 March 2007 (UTC)
- Not by definition. The anticoagulants (e.g. protein C) don't slow down the conversion process. Rather, they inactivate already activated factors. I agree factor VII and prothrombin conversion should be made clearer. When I get to my own computer I will try to address this. JFW | T@lk 23:23, 23 April 2007 (UTC)
- How about one of these as a replacement? I can make changes easily if anybody wants to suggest them:
- E.g. thrombin-mediated factor V activiation is unclear, antithrombin also inactivates factor X. JFW | T@lk 23:24, 23 April 2007 (UTC)
Joe, you're correct. I was just somewhat peeved that my diagram had been replaced :-). I've reinserted yours, which is much better than the one I drew in 2004. In particular, your diagram indicates the new link between thrombin and factor XI, which is in accordance with new paradigms on continuous thrombin generation vs thrombin burst.
As you may have seen, I'm updating the article quite heavily. Your assistance is very much appreciated, particularly in finding the right sources for things that I haven't sourced well at present. JFW | T@lk 20:11, 24 April 2007 (UTC)
Could there be a way to represent the magnitude of the clotting factors using broader arrow size and different font sizes. For example a particular factor might be present at low levels (small font) but can amplify greatly (represent with arrow that begins small but swells to its arrow head). This might provide an intuitive view of why some coagulation factors are indispensible while others can be compensated for. doctorwolfie 16:50, 29 August 2007 (UTC)
This diagram was recently replaced with a simplified version that lacks any of the feedback mechanisms. I think the previous graph was much more informative and should be restored. — Preceding unsigned comment added by 22.214.171.124 (talk) 18:18, 25 June 2012 (UTC)
Only today I discovered there is actually a comprehensive primary text about the history of coagulation. ISBN 1893005909 has a 400 page historical overview of all the characters. It is expensive (Amazon 2nd hand $250) but perhaps my library can order it from the British Library. JFW | T@lk 16:02, 12 September 2006 (UTC)
- Any luck on this? I came to the Talk page kind of dissatisfied with the statement "Theories on the coagulation of blood have existed since antiquity" being followed by an early 1800s fact. I'm curious myself what sort of earlier theories there were. --mordicai. 21:28, 20 January 2007 (UTC)
No luck yet. I've found some more historical material (S.I. Rapaport's historical overview in West J Med 1993) but I have no access to earlier theories. What is interesting is that for practical purposes the ancient Jews knew that stirring blood kept it liquid, as done in the sacrificial service in the Temple in Jerusalem. JFW | T@lk 14:59, 10 June 2007 (UTC)
Too technical for laymen
This is the first Wikipedia article I've ever tried to read that seemed difficult for non-experts to understand. The theories of special relativity and quantum mechanics are mind-bending for most educated people, however, I find their Wikipedia articles easier to follow than this.
This article appears to be a very extensively documented and carefully (even lovingly) composed and edited article. Perhaps the same editors could step back and try to either write a layman's section or else water the technical language down a bit for the rest of us. The "Make Technical Articles Accessible" guideline has good material on how to approach this issue. --A. B. (talk) 22:31, 28 January 2007 (UTC)
I was wondering whether it would be worth having a simple summary near the top for us laymen before diving into the details? I did take AS biology some years ago but the article is still a bit of a tough read...
What I understand from the article without a thorough reading (I was a little putoff but the sheer complexity of the process):
The first hemostasis is that the platelets are activated by and stick to collagen fibres. (They are found outside the blood vessel?) The platelets then release the granules inside them, which ativates other platelets. eerr... so the effect is that they clump together at the wound? (is this a 'haemeostatic plug'?
(this bit I recall from distant memory...) Then the second hemostasis: by a complex chemical process the fibrinogen (soluble) is transformed into fibrin (insoluble). So now the fibrin helps block up the remain gaps and dams the flow of blood.
I guess that at the end of all that, the water evaporates causing the wet squidgy mass on the skin/floor/outside of the body to 'harden' and contract - simple loss of volume. I am actually observing the blood as I write :)
Is this very very crude summary even vaguely correct? 126.96.36.199 11:41, 6 March 2007 (UTC)
I'm editing the article to respond to concerns above. I've added some organisation and have expanded on topics such as pathology and pharmacology.
Any recommendations as to WP:RS? I found the Furie & Furie article, which looks pretty decent & may actually be counted as a source for many parts of the article. JFW | T@lk 01:23, 24 April 2007 (UTC)
Shouldn't we include a scab photo? --Digitalgadget 18:14, 6 July 2007 (UTC)
- Quite right. To be, an article without a picture is pretty useless to visual learners.Chimchar monferno (talk) 01:33, 25 May 2008 (UTC)
- Depends what you measure. Formation of an early platelet plug takes seconds. The bleeding time is definitely shorter than 15 minutes (2-9 depending on method is quoted). More specific in vitro tests of clotting are 11.5-16.0 seconds for the prothrombin time and 26.0-38.0 for the partial thromboplastin time. JFW | T@lk 13:52, 16 July 2008 (UTC)
it requires modification
just a comment, although it has been mentioned correctly under (Physiology, The coagulation cascade) that the new pathways are in a 3 steps rather than as previously known intrensic and extrinsic pathways,but later on the explantion was in according to the old one..
thats why i think it should be modified.
- I agree with you, the old model (extrinsic pathway + intrinsic pathway + common pathway) is no longer followed. The newer textbooks (and my lecturers) now teach the cell-surface model. Shall I attempt to revise this article? Td1wk (talk) 19:04, 8 May 2012 (UTC)
- I have used Pallister CJ and Watson MS (2011). Haematology (2nd Ed.) Scion Publishing. p. 341 as a source for the diagram at the top. This book says that the the classical pathways reflect forms of activation of coagulation that occur in vitro but not in vivo, and that the separate pathways do not exist in vivo. But it goes on to say "The classical concept of blood coagulation has been exceptionally important as a means of understanding the results of laboratory screening tests of coagulation". I think the concept of the classic pathways is still useful to the understanding of haemostasis. Graham Colm (talk) 19:54, 8 May 2012 (UTC)
- OK, as long as we've made the difference apparent I think it could be beneficial to have both. From another reading of the article it seems this is the case. I'll not make any changes. Td1wk (talk) 20:18, 9 May 2012 (UTC)
- I will draw another diagram this weekend that illustrates the currently accepted in vivo pathway. I think it will be useful to have both. You are right, we need to make the differences between the in vitro classical pathways, which remain useful in the interpretation of laboratory tests, and what actually goes on in damaged tissues clear. This will require some skilled writing. I see this as a little like glycolysis – the pathway many of us have had to memorise - which is more complex and convoluted than it first appears, but still provides, in its simplified, textbook form, a good introduction and understanding of metabolism. Please allow me a little time to work on the diagram, then I suggest we revisit this discussion. Graham Colm (talk) 21:05, 9 May 2012 (UTC)
- OK, as long as we've made the difference apparent I think it could be beneficial to have both. From another reading of the article it seems this is the case. I'll not make any changes. Td1wk (talk) 20:18, 9 May 2012 (UTC)
Article requires modification in this aspect. vWF is not in the subendothelian layer, but is present in plasma, endothelian cells and trombocytes. The present statement is:
Damage to blood vessel walls exposes subendothelium proteins, most notably von Willebrand factor (vWF), present under the endothelium
I was surprised to find myself on this page when I searched for "coagulation", since this such a specific instance of a pervasive phenomenon and it isn't a term I ever hear used to refer to blood clotting. I think "Blood clotting" is more natural, common, and recognizable, leaving "coagulation" to redirect to the general colloidal phenomenon (Flocculation). Jojalozzo 02:44, 25 March 2013 (UTC)