Question

q: tissue factor is a crucial initiator of coagulation. it is primarily found on the surface of which of the following cell types?
description: sys2 blood obj3c
a: circulating platelets
b: cells surrounding blood vessels
c: hepatocytes
d: erythrocytes

Explanation:

Tissue factor (TF), also known as thromboplastin, is a transmembrane protein. It is not present on circulating platelets (A) as they are involved in platelet - related hemostasis steps like adhesion and aggregation. Hepatocytes (C) are liver cells mainly involved in protein synthesis (like clotting factors but not tissue factor location in the context of coagulation initiation). Erythrocytes (D) are red blood cells for oxygen transport. TF is expressed on the surface of cells surrounding blood vessels (such as sub - endothelial cells). When there is vascular injury, these cells are exposed to the blood, and TF initiates the extrinsic coagulation pathway by binding to factor VIIa.

Answer:

B. Cells surrounding blood vessels