Question

The life span of thrombocytes is (a) 4 to 5 weeks (b) 3 to 4 weeks (c) 3 to 7 days (d) none of these.

Short answer

The life span of thrombocytes is 3 to 7 days (Option c).

Step-by-step solution

Understanding the Concept

Thrombocytes, also known as platelets, are small cell fragments in the blood that are essential for normal blood clotting. Knowledge of their lifespan is important in understanding their function and turnover in the body.

Recall the Correct Information

Recall from biology lessons or textbooks that the average life span of thrombocytes is typically cited as 7 to 10 days in humans.

Choose the Closest Answer

Identify which option is closest to the average lifespan of thrombocytes. Since none of the given options matches exactly 7 to 10 days, choose the one that covers the correct range.

Key concepts

Blood Clotting

Blood clotting, also known as coagulation, is a vital process that prevents excessive bleeding when a blood vessel is injured. It involves a complex series of events where blood changes from a liquid to a gel, forming a blood clot. This process can be broken down into three stages: vasoconstriction, temporary blockage by a platelet plug, and coagulation, where fibrin strands reinforce the platelet plug.

Firstly, when a vessel is damaged, it will constrict, slowing the flow of blood. Platelets then adhere to the site of injury and release chemicals that trigger further platelet activation and accumulation, forming a plug. Lastly, coagulation factors (proteins in the blood plasma), mainly prothrombin and fibrinogen, are activated. Prothrombin converts into thrombin, which then transforms fibrinogen into fibrin. Fibrin strands weave through the plug, solidifying the clot and sealing the wound.

Platelets Function

Platelets, or thrombocytes, serve several critical roles in the body, chiefly their contribution to blood clotting. These cell fragments act as first responders to vascular injury. When they encounter a damaged blood vessel, they become activated. Activated platelets change shape to maximize contact area and release chemical signals.

The functions of platelets can be outlined as follows:

• Adhesion: Platelets stick to exposed collagen in damaged vessel walls.
• Activation: Platelets change shape and release chemical signals that attract more platelets to the site.
• Aggregation: Platelets clump together to form a plug that fills in the broken area.
• Secreting substances for blood clot reinforcement.

Following the formation of the initial plug, platelets also facilitate the strengthening and stabilization of the clot through the coagulation cascade, highlighting their essential role in preventing blood loss.

Cell Fragments in Blood

Platelets are not complete cells, but rather small fragments of cells known as cell fragments. They originate from larger cells called megakaryocytes in the bone marrow. These megakaryocytes release platelets into the bloodstream where they circulate until needed for clotting or when they reach the end of their lifespan.

To understand their functionality, consider that these fragments are equipped with specific proteins on their surface. These proteins enable platelets to interact with other blood components and the vessel wall, essential for stopping bleeding. Unlike full cells, platelets do not have a nucleus but contain granules loaded with clot-promoting substances. In their short lifespan, which typically is within the range of 7 to 10 days, they are crucial for maintaining hemostasis (the process that stops bleeding) and supporting the repair of the vascular system after injury.