from PART I - PHYSIOLOGY
Published online by Cambridge University Press: 10 May 2010
Introduction
Before the early 1960s interaction between platelets and plasmatic thrombin or ‘thromboplastin’ generation was the subject of intensive study. Since the introduction of the aggregation and adhesion methods, most studies on platelets are done under conditions where clotting is prevented, whereas blood coagulation is usually studied in the absence of platelets. In this way only indirect information (e.g. recognition of thrombin-receptors) is obtained on the interaction between platelet and plasma. Direct information on the platelet-clotting system reinforcement loops has been reappearing only recently.
In the body, platelet activation and thrombin generation are two intimately linked processes. Thrombin is a potent platelet activator and adequate thrombin formation is impossible without activated platelets. Because thrombin generation and platelet activation are mutually interdependent, each process requiring the product of the other for its full activity, the two are interlocked in positive feedback. Unlike the better known negative feedback that has regulatory properties, a positive feedback loop amplifies product formation explosively. Hemostasis is an intricate complex of positive and negative feedback loops. Here, we will focus on the amplification mechanism constituted by the platelet–clotting system interaction. The thrombin induced positive feedback loop has been known for over half a century (see fig. 26.1 from ref.1) but only recently has it again become a focus of wider interest.
To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.