Coagulation of the blood can be initiation from two different pathways that both result in formation of thrombin which converts blood soluble fibrinogen into the insoluble fibrin clot at the site of injury. The intrinsic pathway is activated by trauma inside vasculature and is activated by platelets, exposed endothelium and collagen. In the liver the coagulation factors VII, IX, and X are produced there as they are vitamin K-dependent proteins. Exposed collagen from broken vessels binds to factor XII activating it to XIIa which converts prekallikrein and factor XI to kallikrein and factor XIa respectively. The extrinsic pathway is activated by the external trauma of blood escaping the vasculature system as the membrane-bound protein tissue factor (TF) is exposed to factors VII or VIIa in the plasma forming a strong activator complex. This activator complex of VIIa and TF converts factor X to the activated form. Both the intrinsic and extrinsic pathways lead to the prothrombinase complex as both pathways activate factor X, an important player in the complex. The prothrombinase complex converts prothrombin to thrombin further allowing the conversion of insoluble fibrinogen into fibrin. Fibrin at first is loose and unstable and is stabilized by coagulation factor XIIIa which cross-links them to form the fibrin clot/mesh that stops blood leaking from the vasculature system. The activated proteins are colored orange.
The Wiggers diagram is a tool used to teach cardiovascular physiology which typically includes pressure and volume changes during ventricular contractions (cardiac cycle). At the end of diastole (relaxation phase), the mitral valve closes and the left atrium contracts. When the left ventricular pressure exceeds aortic pressure, the aortic valve opens (systole), hits a peak and decreases as the volume in the left ventricle decreases. The aortic valve closes and slightly increases the pressure in the aorta (incisura). When the left ventricular pressure is below the left atrial pressure, the mitral valve opens and the left ventricle can begin filling with blood in order to repeat the process.
