Question

Prothrombin required for blood clotting is produced in (a) stomach (b) liver (c) spleen (d) pancreas.

Short answer

The correct answer is (b) liver.

Step-by-step solution

Recall the function of Prothrombin

Understand that prothrombin is a protein involved in blood clotting. It is an essential component for the coagulation of blood and is converted to its active form, thrombin, during the clotting process.

Identify the site of Prothrombin production

Identify that prothrombin is produced in the liver, which is responsible for the synthesis of various blood clotting factors, including prothrombin.

Choose the correct option

With the knowledge that the liver is where prothrombin is produced, select (b) liver as the right answer.

Key concepts

Blood Clotting

Blood clotting, also known as coagulation, is a crucial process in preventing excessive bleeding when the vascular system is injured. It involves a complex series of events designed to form a stable clot over a damaged vessel. One of the essential proteins in this process is prothrombin, which is converted into the enzyme thrombin when a vessel is damaged. Thrombin then catalyzes the conversion of fibrinogen, a soluble protein, into fibrin threads that form the structural basis of a blood clot.

Understanding blood clotting requires a grasp of its stages, which include the vascular phase, the platelet phase, and the coagulation phase. An initial vasoconstriction response reduces blood flow, followed by the formation of a temporary 'platelet plug,' and finally, the sequence that leads to a sturdy fibrin clot—the last part being where prothrombin plays a pivotal role.

Importance of the Coagulation Cascade

The coagulation cascade is the sequence of reactions, often demonstrated as a 'cascade', due to the sequential activation of coagulation factors leading to blood clotting. During this cascade, prothrombin is activated, highlighting its significance in the overall process.

It's important to note that while clotting is essential for healing, unintended clotting within blood vessels can lead to conditions such as deep vein thrombosis or stroke.

Liver Function

The liver, a large organ located in the upper right portion of the abdomen, plays a central role in many vital processes, including metabolism, detoxification, and the production of biochemicals necessary for digestion. One of its lesser-known yet critical functions is the synthesis of blood coagulation factors, such as prothrombin. Prothrombin production in the liver is a testament to its ability to synthesize complex proteins.

The liver's involvement in producing coagulation factors also extends to its regulation of other proteins and enzymes involved in the coagulation cascade. It's integral in maintaining the delicate balance between clot formation and dissolution to prevent either excessive bleeding or clotting.

Connection with Vitamin K

The synthesis of prothrombin by the liver is vitamin K-dependent, meaning a diet sufficient in vitamin K is essential for the liver to produce functioning coagulation factors. Without adequate vitamin K, the liver cannot produce prothrombin at optimal levels, which can lead to an increased risk of bleeding.

Blood Coagulation Factors

Blood coagulation factors are specialized proteins in the plasma that work collaboratively to ensure proper blood clotting. There are several of these factors, each with a specific function within the clotting cascade. They are designated by Roman numerals I through XIII.

When blood vessel damage occurs, these factors activate in a domino-effect to form a clot where it's needed. Prothrombin, known as factor II, is one of these vital components. Prior to injury, prothrombin circulates in the blood in its inactive form but quickly transforms into its active form, thrombin, upon activation by factor X, another coagulation factor.

Hereditary Clotting Disorders

Understanding coagulation factors is crucial, especially when considering hereditary conditions like hemophilia, where specific coagulation factors are deficient or dysfunctional, leading to problematic bleeding episodes.

Adequate levels and functionality of all coagulation factors, including prothrombin, are vital for the integrity of the coagulation cascade, emphasizing their importance in maintaining hemostasis—the stoppage of blood loss.