What substances activate the release of prothrombin?

Prothrombin release is primarily activated by the presence of certain substances that promote the coagulation cascade, notably tissue factor (thromboplastin) and calcium ions (Ca²⁺). Tissue factor is exposed at the site of vascular injury and interacts with factor VII, leading to the activation of factor X, which ultimately converts prothrombin to thrombin. Additionally, phospholipids from activated platelets also play a crucial role in this process.