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.

<p>False</p> Signup and view all the answers

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

<p>False</p> Signup and view all the answers

Secondary hemostasis is also called the Coagulation Cascade.

<p>True</p> Signup and view all the answers

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

<p>True</p> Signup and view all the answers

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

<p>True</p> Signup and view all the answers

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

<p>False</p> Signup and view all the answers

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

<p>True</p> Signup and view all the answers

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

<p>True</p> Signup and view all the answers

Defects in haemostasis can lead to thrombotic & bleeding disorders.

<p>True</p> Signup and view all the answers

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

<p>True</p> Signup and view all the answers

Vasoconstriction is mediated by reflex neurogenic mechanisms and released vasodilators.

<p>False</p> Signup and view all the answers

The coagulation cascade is part of primary haemostasis.

<p>False</p> Signup and view all the answers

Fibrinolysis dissolves the clot to prevent localized vasoconstriction.

<p>False</p> Signup and view all the answers

What is the main purpose of haemostasis?

<p>To prevent significant blood loss after vascular injury</p> Signup and view all the answers

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

<p>Red blood cells</p> Signup and view all the answers

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

<p>Localised vasoconstriction</p> Signup and view all the answers

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

<p>Primary haemostasis</p> Signup and view all the answers

What is the main function of secondary haemostasis?

<p>Strengthening and reinforcing the platelet plug</p> Signup and view all the answers

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

<p>Tertiary haemostasis</p> Signup and view all the answers

What is the primary function of localised vasoconstriction in haemostasis?

<p>To reduce blood flow to the injury site and retard blood loss</p> Signup and view all the answers

Which statement accurately describes the regulation of haemostasis?

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

What role does fibrinolysis play in haemostasis?

<p>&quot;Fibrinolysis dissolves the clot once blood vessel integrity has been restored.</p> Signup and view all the answers

What is the primary function of primary haemostasis?

<p>Plugging the breach in the blood vessel</p> Signup and view all the answers

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

<p>Vasoconstriction</p> Signup and view all the answers

What is the main goal of secondary haemostasis?

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

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

<p>Thrombin</p> Signup and view all the answers

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

<p>Require vitamin K for synthesis</p> Signup and view all the answers

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

<p>von Willebrand factor</p> Signup and view all the answers

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

<p>Formation of a primary haemostatic plug</p> Signup and view all the answers

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

<p>Vascular injury</p> Signup and view all the answers

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

<p>Factor VIII</p> Signup and view all the answers

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

<p>Large molecules absent from serum</p> Signup and view all the answers

What happens upon endothelial injury during platelet adhesion?

<p>Platelets bind directly to collagen</p> Signup and view all the answers

What is the major goal of primary haemostasis?

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

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

<p>Increased thromboxane A2 (TXA2) production</p> Signup and view all the answers

What is the main goal of primary haemostasis?

<p>To stop hemorrhage in small blood vessels</p> Signup and view all the answers

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

<p>Platelet-activating factor (PAF)</p> Signup and view all the answers

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

<p>Tertiary haemostasis</p> Signup and view all the answers

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

<p>Cross bridges with adjacent platelets</p> Signup and view all the answers

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

<p>Factor VIIa</p> Signup and view all the answers

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

<p>They are large molecules absent from serum</p> Signup and view all the answers

What is the primary function of localised vasoconstriction in haemostasis?

<p>To reduce blood flow to the injury site</p> Signup and view all the answers

What is the primary physiological significance of haemostasis?

<p>Preventing significant blood loss after vascular injury</p> Signup and view all the answers

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

<p>Secondary haemostasis (coagulation cascade)</p> Signup and view all the answers

Which of the following is a key player in haemostasis?

<p>Platelets</p> Signup and view all the answers

What is the main goal of primary haemostasis?

<p>Forming a localized plug in injured vessels</p> Signup and view all the answers

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

<p>Tertiary haemostasis (fibrinolysis)</p> Signup and view all the answers

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

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

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

<p>Serotonin</p> Signup and view all the answers

What occurs upon endothelial injury during platelet adhesion?

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

What role does fibrinolysis play in haemostasis?

<p>Dissolves the clot once blood vessel integrity has been restored</p> Signup and view all the answers

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

<p>Strengthens and reinforces the platelet plug</p> Signup and view all the answers

What are the key steps involved in haemostasis?

<p>Primary haemostasis, secondary haemostasis, and tertiary haemostasis</p> Signup and view all the answers

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

<p>Coagulation proteins</p> Signup and view all the answers

What is the main physiological significance of haemostasis?

<p>Preventing significant blood loss after vascular injury</p> Signup and view all the answers

What is the primary function of localised vasoconstriction in haemostasis?

<p>To reduce blood flow to the injury site and retard blood loss</p> Signup and view all the answers

Which natural process prevents significant blood loss after vascular injury?

<p>Haemostasis</p> Signup and view all the answers

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

<p>Tertiary haemostasis or fibrinolysis</p> Signup and view all the answers

What is the main goal of primary haemostasis?

<p>Plugging the breach in the blood vessel</p> Signup and view all the answers

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

<p>Reflex neurogenic mechanisms and released vasoconstrictors</p> Signup and view all the answers

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

<p>The blood vessel wall, platelets, coagulation proteins, and other proteins</p> Signup and view all the answers

What does haemostasis depend on?

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

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

<p>Platelet adhesion, platelet activation, platelet aggregation, platelet plug formation</p> Signup and view all the answers

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

<p>vWf, P-selectin, FV &amp; FXIII, ADP, serotonin, Ca++</p> Signup and view all the answers

What are the three key features of the coagulation cascade?

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

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

<p>Large molecules, absent from serum</p> Signup and view all the answers

What are the coagulation factors included in the Prothrombin Group?

<p>II, VII, IX, X</p> Signup and view all the answers

What is the main goal of secondary haemostasis?

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

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

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

What is the primary function of localised vasoconstriction in haemostasis?

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

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

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

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

<p>Require contact with negatively charged surface for activation</p> Signup and view all the answers

What are the major activation requirements for the coagulation cascade?

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

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

<p>Acts as a physical barrier separating circulating platelets from thrombogenic substances</p> 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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Haemostasis 1 (2023-24) PDF

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.

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