Haemostasis 1 Week 25

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Questions and Answers

Platelet adhesion is the first step in secondary hemostasis.

False

Platelets bind adhesive proteins via the GP1b-IX-V complex to fibrinogen.

False

The release of contents of preformed cytoplasmic granules during platelet activation includes serotonin.

True

Activation and expression of GPIIb/IIIa receptors occur during platelet adhesion.

False Signup and view all the answers

Agonist-activated platelet GPIIb/IIIa receptors bind vWf to form a primary haemostatic plug.

False Signup and view all the answers

Secondary hemostasis is also called the Coagulation Cascade.

True Signup and view all the answers

The term 'haemostasis' refers to the prevention of significant blood loss after vascular injury.

True Signup and view all the answers

Primary haemostasis involves the formation of a localized plug in injured vessels.

True Signup and view all the answers

Secondary haemostasis involves localised vasoconstriction to reduce blood flow to the injury site.

False Signup and view all the answers

Tertiary haemostasis dissolves the clot once blood vessel integrity has been restored.

True Signup and view all the answers

Haemostasis depends on a series of events involving the blood vessel wall, platelets, coagulation proteins, and other proteins.

True Signup and view all the answers

Defects in haemostasis can lead to thrombotic & bleeding disorders.

True Signup and view all the answers

Haemostasis keeps blood fluid and clot-free in normal blood vessels.

True Signup and view all the answers

Vasoconstriction is mediated by reflex neurogenic mechanisms and released vasodilators.

False Signup and view all the answers

The coagulation cascade is part of primary haemostasis.

False Signup and view all the answers

Fibrinolysis dissolves the clot to prevent localized vasoconstriction.

False Signup and view all the answers

What is the main purpose of haemostasis?

To prevent significant blood loss after vascular injury Signup and view all the answers

Which of the following is NOT one of the key players in haemostasis?

Red blood cells Signup and view all the answers

What is the first step in the 4-step process of haemostasis?

Localised vasoconstriction Signup and view all the answers

During which step of haemostasis does the formation of a localized plug in injured vessels occur?

Primary haemostasis Signup and view all the answers

What is the main function of secondary haemostasis?

Strengthening and reinforcing the platelet plug Signup and view all the answers

Which step of haemostasis involves dissolving the clot once blood vessel integrity has been restored?

Tertiary haemostasis Signup and view all the answers

What is the primary function of localised vasoconstriction in haemostasis?

To reduce blood flow to the injury site and retard blood loss Signup and view all the answers

Which statement accurately describes the regulation of haemostasis?

'Haemostasis' aims to keep blood fluid and clot-free in normal blood vessels. Signup and view all the answers

What role does fibrinolysis play in haemostasis?

"Fibrinolysis dissolves the clot once blood vessel integrity has been restored. Signup and view all the answers

What is the primary function of primary haemostasis?

Plugging the breach in the blood vessel Signup and view all the answers

Which of the following is NOT one of the key events during primary haemostasis?

Vasoconstriction Signup and view all the answers

What is the main goal of secondary haemostasis?

To form a stable fibrin clot at the site of injury Signup and view all the answers

Which enzyme is responsible for converting fibrinogen to fibrin during the coagulation cascade?

Thrombin Signup and view all the answers

What are the basic properties of the coagulation factors in the Prothrombin Group?

Require vitamin K for synthesis Signup and view all the answers

During platelet activation, which of the following substances is NOT released from preformed cytoplasmic granules?

von Willebrand factor Signup and view all the answers

What occurs when agonist-activated platelet GPIIb/IIIa receptors bind fibrinogen?

Formation of a primary haemostatic plug Signup and view all the answers

What is the first step in the 4-step process of haemostasis?

Vascular injury Signup and view all the answers

Which factor is synthesized in the liver and denoted by a lower case 'a' after its factor number?

Factor VIII Signup and view all the answers

What property distinguishes the Coagulation Factors in the Fibrinogen Group from other groups?

Large molecules absent from serum Signup and view all the answers

What happens upon endothelial injury during platelet adhesion?

Platelets bind directly to collagen Signup and view all the answers

What is the major goal of primary haemostasis?

To dissolve the clot once blood vessel integrity has been restored Signup and view all the answers

What occurs during platelet activation and expression of GPIIb/IIIa receptors?

Increased thromboxane A2 (TXA2) production Signup and view all the answers

What is the main goal of primary haemostasis?

To stop hemorrhage in small blood vessels Signup and view all the answers

During platelet activation, which of the following substances is NOT released from preformed cytoplasmic granules?

Platelet-activating factor (PAF) Signup and view all the answers

Which step of haemostasis involves dissolving the clot once blood vessel integrity has been restored?

Tertiary haemostasis Signup and view all the answers

What occurs when agonist-activated platelet GPIIb/IIIa receptors bind fibrinogen?

Cross bridges with adjacent platelets Signup and view all the answers

Which factor is synthesized in the liver and denoted by a lower case 'a' after its factor number?

Factor VIIa Signup and view all the answers

What property distinguishes the Coagulation Factors in the Fibrinogen Group from other groups?

They are large molecules absent from serum Signup and view all the answers

What is the primary function of localised vasoconstriction in haemostasis?

To reduce blood flow to the injury site Signup and view all the answers

What is the primary physiological significance of haemostasis?

Preventing significant blood loss after vascular injury Signup and view all the answers

Which step of haemostasis involves strengthening and reinforcing the platelet plug?

Secondary haemostasis (coagulation cascade) Signup and view all the answers

Which of the following is a key player in haemostasis?

Platelets Signup and view all the answers

What is the main goal of primary haemostasis?

Forming a localized plug in injured vessels Signup and view all the answers

Which step of haemostasis involves dissolving the clot once blood vessel integrity has been restored?

Tertiary haemostasis (fibrinolysis) Signup and view all the answers

What property distinguishes the Coagulation Factors in the Fibrinogen Group from other groups?

Denoted by a lower case 'a' after its factor number Signup and view all the answers

During platelet activation, which of the following substances is released from preformed cytoplasmic granules?

Serotonin Signup and view all the answers

What occurs upon endothelial injury during platelet adhesion?

Platelet activation and expression of GPIIb/IIIa receptors Signup and view all the answers

What role does fibrinolysis play in haemostasis?

Dissolves the clot once blood vessel integrity has been restored Signup and view all the answers

What occurs when agonist-activated platelet GPIIb/IIIa receptors bind fibrinogen?

Strengthens and reinforces the platelet plug Signup and view all the answers

What are the key steps involved in haemostasis?

Primary haemostasis, secondary haemostasis, and tertiary haemostasis Signup and view all the answers

Which proteins are involved in strengthening and reinforcing the platelet plug in haemostasis?

Coagulation proteins Signup and view all the answers

What is the main physiological significance of haemostasis?

Preventing significant blood loss after vascular injury Signup and view all the answers

What is the primary function of localised vasoconstriction in haemostasis?

To reduce blood flow to the injury site and retard blood loss Signup and view all the answers

Which natural process prevents significant blood loss after vascular injury?

Haemostasis Signup and view all the answers

What dissolves the clot once blood vessel integrity has been restored in haemostasis?

Tertiary haemostasis or fibrinolysis Signup and view all the answers

What is the main goal of primary haemostasis?

Plugging the breach in the blood vessel Signup and view all the answers

Which substances are involved in the process of localised vasoconstriction in haemostasis?

Reflex neurogenic mechanisms and released vasoconstrictors Signup and view all the answers

What are the major players in the finely tuned process of haemostasis?

The blood vessel wall, platelets, coagulation proteins, and other proteins Signup and view all the answers

What does haemostasis depend on?

An intricate series of events involving the blood vessel wall, platelets, coagulation proteins, and other proteins Signup and view all the answers

What are the 4 key events initiated by vascular injury in primary haemostasis?

Platelet adhesion, platelet activation, platelet aggregation, platelet plug formation Signup and view all the answers

What are the contents of preformed cytoplasmic granules released during platelet activation?

vWf, P-selectin, FV & FXIII, ADP, serotonin, Ca++ Signup and view all the answers

What are the three key features of the coagulation cascade?

Sequence of enzymatic reactions, activation reactions requiring phospholipid-rich membrane surface and enzyme, traditionally divided into intrinsic, extrinsic, and common pathways Signup and view all the answers

What are the basic properties of the Coagulation Factors in the Fibrinogen Group?

Large molecules, absent from serum Signup and view all the answers

What are the coagulation factors included in the Prothrombin Group?

II, VII, IX, X Signup and view all the answers

What is the main goal of secondary haemostasis?

To form a stable fibrin clot at the site of injury Signup and view all the answers

What is the physiological significance of intact endothelium in primary haemostasis?

Acts as a physical barrier separating circulating platelets from thrombogenic substances Signup and view all the answers

What is the primary function of localised vasoconstriction in haemostasis?

To transiently reduce blood flow to the injury site and retard blood loss Signup and view all the answers

What is the significance of the release of contents of preformed cytoplasmic granules during platelet activation?

To facilitate various changes in platelets, including shape change, granule release, and membrane phospholipid metabolism Signup and view all the answers

What is the primary role of the Coagulation Factors in the Contact Group?

Require contact with negatively charged surface for activation Signup and view all the answers

What are the major activation requirements for the coagulation cascade?

Negatively charged phospholipid-rich membrane surface, enzyme, substrate, cofactor, and Ca++ Signup and view all the answers

What is the primary function of intact endothelium in primary haemostasis?

Acts as a physical barrier separating circulating platelets from thrombogenic substances Signup and view all the answers

Study Notes

Haemostasis

Haemostasis is the prevention of significant blood loss after vascular injury.
It depends on a series of events involving the blood vessel wall, platelets, coagulation proteins, and other proteins.

Primary Haemostasis

Involves the formation of a localized plug in injured vessels.
Includes vasoconstriction to reduce blood flow to the injury site.

Platelet Adhesion

The first step in secondary haemostasis.
Platelets bind to adhesive proteins via the GP1b-IX-V complex to fibrinogen.
During platelet activation, the contents of preformed cytoplasmic granules, including serotonin, are released.
Activation and expression of GPIIb/IIIa receptors occur during platelet adhesion.

Secondary Haemostasis

Also known as the Coagulation Cascade.
Involves the formation of a primary haemostatic plug.
Agonist-activated platelet GPIIb/IIIa receptors bind vWf to form the plug.

Tertiary Haemostasis

Involves dissolving the clot once blood vessel integrity has been restored.
Fibrinolysis dissolves the clot to prevent localized vasoconstriction.

Coagulation Factors

The Prothrombin Group consists of factors VII, IX, and X.
The Fibrinogen Group consists of factors I, V, and VIII.
The Contact Group consists of factors XI, XII, and pre-kallikrein.

Regulation of Haemostasis

Haemostasis is regulated by a series of events involving the blood vessel wall, platelets, coagulation proteins, and other proteins.
Defects in haemostasis can lead to thrombotic and bleeding disorders.

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Description

Learn about haemostasis and its significance, the key players, the 4 steps of haemostasis, primary and secondary haemostasis, tertiary haemostasis, and regulation of haemostasis in this lecture. Understand the learning outcomes of the lecture.