Blood Vessel Injury and Response

Questions and Answers

What is the primary function of the platelets in the blood clotting process?

To form an initial plug to contain the blood

What is the purpose of the fibrin strands in the blood clotting process?

To act as a mesh to hold the platelet plug together solidly

What is the characteristic of fibrin molecules or proteins?

They have a natural affinity for each other

Why are fibrin molecules not found circulating in the blood?

Because they would join together and form unwanted clots Signup and view all the answers

What is the purpose of the extra piece attached to fibrin in the blood?

To prevent it from joining to itself Signup and view all the answers

What is the result of the platelets coming together to form an initial plug?

The prevention of blood loss Signup and view all the answers

What would happen if fibrin molecules were able to circulate freely in the blood?

They would join together and form unwanted clots Signup and view all the answers

What is the final result of the blood clotting process?

The prevention of blood loss Signup and view all the answers

What would happen if the negative feedback loops in the clotting system did not exist?

The system would spiral out of control, leading to excessive clotting Signup and view all the answers

What is the role of thrombin in the clotting system?

It stimulates the production of plasmin and anti-thrombin Signup and view all the answers

What is the primary function of plasmin in the clotting system?

To break down fibrin mesh networks Signup and view all the answers

What is the term for a bleeding disorder caused by a defect in the clotting system?

Hemophelia Signup and view all the answers

Which factor deficiency is associated with Hemophelia A?

Factor VIII Signup and view all the answers

What pathway do the factors associated with Hemophelia target?

Intrinsic pathway Signup and view all the answers

What is the role of anti-thrombin in the clotting system?

It decreases the amount of thrombin produced Signup and view all the answers

What would be the result of a factor XI deficiency?

Hemophelia C Signup and view all the answers

What is the primary function of fibrinogen in the body?

To convert into fibrin at the site of injury Signup and view all the answers

What is the concentration of factor I (fibrinogen) in blood?

3,000 micro-grams per milliliter Signup and view all the answers

What triggers the conversion of fibrinogen to fibrin at the site of injury?

The release of new proteins from damaged endothelial cells Signup and view all the answers

What activates factor X in the extrinsic pathway?

Activated VII Signup and view all the answers

Why is thrombin a more efficient converter of fibrinogen to fibrin than the 'little yellow guys'?

Thrombin can catalyze the conversion of multiple fibrinogen molecules Signup and view all the answers

What is the inactive form of thrombin called?

Prothrombin Signup and view all the answers

What is the role of the intrinsic pathway in blood coagulation?

It amplifies the coagulation response Signup and view all the answers

What is the name of the pathway that involves the clotting cascade starting from XII?

Intrinsic pathway Signup and view all the answers

What is the function of thrombin in the coagulation cascade?

To activate factors V, VII, VIII, XI, and XIII Signup and view all the answers

What is the role of XII in the clotting cascade?

It converts XI to its active form Signup and view all the answers

What is the role of factor XIII in the coagulation cascade?

To form cross links between fibrin strands Signup and view all the answers

What is the relationship between X and V in the clotting cascade?

X and V work together because they are both multiples of 5 Signup and view all the answers

What is the difference between the extrinsic and intrinsic pathways?

The extrinsic pathway is the 'spark' that initiates coagulation, while the intrinsic pathway is the 'workhorse' that amplifies it Signup and view all the answers

What is the function of tissue factor in the coagulation cascade?

To activate factor VII Signup and view all the answers

What happens to XI when it is activated?

It converts IX to its active form Signup and view all the answers

What is the role of thrombin in the clotting cascade?

It converts fibrinogen to fibrin Signup and view all the answers

What is the result of the coagulation cascade?

The formation of a clot Signup and view all the answers

What is the relationship between the arrows in the clotting cascade diagram?

They represent a catalytic conversion Signup and view all the answers

What is the significance of factor XII in the coagulation cascade?

It is not necessary for coagulation to occur Signup and view all the answers

What is the difference between the green arrow and the white arrows in the diagram?

The green arrow represents the formation of fibrin strands, while the white arrows represent the activation of factors Signup and view all the answers

Study Notes

Blood Vessel Injury and Clotting

When a blood vessel gets hurt, its walls break open, and cells no longer seal the vessel, which can lead to blood loss.
The body has a mechanism to contain the blood and prevent excessive loss.

Initial Plug Formation

Platelets circulating in the body come to the site of injury and form an initial plug to stop the bleeding.
The platelet plug is not solid enough, and the body needs a second mechanism to solidify it.

Fibrin Strands and Fibrinogen

Fibrin strands, composed of fibrin sub-units or proteins, act as a mesh to hold the platelet plug together.
Fibrin molecules have a natural affinity for each other, forming a polymer when brought together.
Fibrinogen is the precursor to fibrin, but it cannot circulate in the blood because it would form fibrin strands spontaneously.

Fibrinogen Conversion to Fibrin

When the endothelium is injured, new proteins are exposed or released, which trigger the conversion of fibrinogen to fibrin.
Thrombin is the enzyme that converts fibrinogen to fibrin.

Thrombin and Clotting Cascade

Thrombin is activated from an inactive form called prothrombin.
Thrombin activates other clotting factors, leading to a cascade of reactions that ultimately form a fibrin mesh.
The clotting cascade is an amplification sequence, with each step increasing the amount of active clotting factors.

Intrinsic and Extrinsic Pathways

There are two pathways that lead to the formation of fibrin: the intrinsic pathway and the extrinsic pathway.
The intrinsic pathway is the "workhorse" that does most of the coagulation, while the extrinsic pathway is the "spark" that initiates the process.
The extrinsic pathway is activated by tissue factor, which is exposed or released when the endothelium is injured.

Thrombin's Role in Clotting

Thrombin activates factors V, VII, VIII, XI, and XIII, which are necessary for the intrinsic pathway.
Thrombin also has a positive feedback loop, which can lead to an overproduction of fibrin if left unchecked.

Negative Feedback Loops

To prevent excessive clotting, there are negative feedback loops that reduce the amount of thrombin and fibrin produced.
Examples of negative feedback loops include thrombin stimulating the production of anti-thrombin and plasmin, which break down fibrin meshes.

Hemophilia

If the clotting system doesn't work, it can lead to excessive bleeding, a condition known as hemophilia.
There are three types of hemophilia: A, B, and C, which are caused by deficiencies in factors VIII, IX, and XI, respectively.

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Description

What happens when a blood vessel gets hurt and how the body responds to contain the blood. Learn about the process of blood vessel injury and repair.