Pressure & Flow In Arteries & Veins 3 Flashcards
Describe the risk associated with inappropriate clotting in the body.
Inappropriate clotting can lead to the formation of a thrombus that may break off and cause serious issues like myocard infarction, stroke, or pulmonary embolism.
Define thrombus in the context of blood clotting.
A thrombus is a blood clot that forms within a blood vessel and can potentially detach and block blood flow in another part of the body.
How does the process of clotting in blood vessels involve platelet plug formation?
When blood vessels are damaged, platelets become activated by collagen in the basement membrane, leading to the formation of a platelet plug.
Describe the two distinct mechanisms involved in blood clotting.
Blood clotting involves the formation of a platelet plug followed by the formation of a fibrin clot.
Explain the role of platelets in the process of blood clotting.
Platelets float in the blood and become activated upon contact with collagen in damaged blood vessels, leading to the formation of a platelet plug.
Describe the role of fibrin in the clotting process.
Fibrin is a large, insoluble protein that forms a mesh over the platelet plug, acting as the mortar that binds the platelets together.
Define thrombin and its function in clotting.
Thrombin is the enzyme responsible for converting fibrinogen into fibrin, playing a crucial role in the formation of a sturdier fibrin clot.
How does the endothelium prevent inappropriate clotting?
The endothelium forms a physical barrier to prevent platelets from contacting the collagen of the basement membrane, secretes prostacyclin and nitric oxide to inhibit platelet aggregation, and produces TFPI to stop thrombin production.
Do platelets and fibrin work together in the clotting process?
Yes, platelets act as the bricks in forming a plug, while fibrin acts as the mortar that binds them together to create a stable clot.
Describe the function of TFPI in clotting regulation.
TFPI, produced by the endothelium, inhibits thrombin production, thereby reducing the conversion of fibrinogen into fibrin and inhibiting the formation of a fibrin clot.
Describe the role of thrombomodulin expressed by the endothelium.
Thrombomodulin binds to thrombin and inactivates it, preventing the conversion of fibrinogen into fibrin and inhibiting the fibrin clot.
What is the function of heparin expressed by the endothelium?
Heparin also inactivates thrombin through a different mechanism.
How does tissue plasminogen activator (t-PA) function in response to a blood clot?
t-PA converts the inactive precursor plasminogen into active plasmin, which acts to digest clots.
What is another term for tissue plasminogen activator (t-PA) and what is its medical use?
t-PA is known as a clot-busting drug or thrombolysis, commonly used for the treatment of ischaemic stroke, myocardial infarction, and pulmonary embolism.
Summarize the anti-clotting mechanisms of the endothelium described in the content.
The endothelium has mechanisms to prevent platelet aggregation, inhibit fibrin clot formation, and digest clots if they form.
