Haemostasis and Thrombosis Overview

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Questions and Answers

What is the primary physiological response of the body to vessel injury?

Inflammation

Nerve regeneration

Haemostasis (correct)

Hemoglobin synthesis

Which step involves the temporary blocking of the injury site in haemostasis?

Vasoconstriction

Activation of platelets (correct)

Skin regeneration

Activation of the immune response

What occurs as a result of the activation of the coagulation cascade in the haemostasis process?

Production of red blood cells

Vasodilation of blood vessels

Reduction of blood pressure

Thrombus formation (correct)

Which of the following best describes the role of fibrin in haemostasis?

A protein that seals the defect in the blood vessel Signup and view all the answers

What is the impact of ischaemia in the context of clot formation?

Causes tissue damage and can lead to infarction Signup and view all the answers

What describes the composition of a thrombus?

A solid or semi-solid mass formed from blood components Signup and view all the answers

Which of the following correctly represents the relationship between ischaemia and infarction?

Ischaemia can occur without leading to an infarction. Signup and view all the answers

What role does plasminogen play in the fibrinolytic system?

It is converted to plasmin which leads to clot lysis. Signup and view all the answers

Which statement best differentiates thrombosis from post-mortem blood separation?

Thrombosis is a physiological process during life, while blood separation occurs after death. Signup and view all the answers

What is the primary role of fibrinogen in blood coagulation?

It is converted into fibrin, creating a stable clot. Signup and view all the answers

What term is used to describe the physiological process that involves the dissolution of a thrombus?

Fibrinolysis Signup and view all the answers

Identify a common characteristic of a thrombus formed post-mortem.

It is often referred to as 'chicken fat' clot. Signup and view all the answers

Which condition is characterized by the presence of a thrombus due to endothelial injury?

Disseminated intravascular coagulopathy (DIC) Signup and view all the answers

What is the primary consequence of severe endothelial injury mentioned in relation to the abdominal aorta?

Narrowing and obstruction Signup and view all the answers

Which structure is most likely to show significant changes due to complicated atheroma?

Abdominal aorta below the renal arteries Signup and view all the answers

What histological feature would you expect to see in low-power microscopy of an area affected by thrombus?

Turbulent flow Signup and view all the answers

What condition is most likely to develop as a result of thrombus formation in lower limb veins?

Deep vein thrombosis Signup and view all the answers

Which pathological change is NOT associated with endothelial injury?

Improved endothelial function Signup and view all the answers

What clinical manifestation might arise from turbulent flow due to endothelial injury?

Thrombus formation Signup and view all the answers

Which of the following terms best describes the pathological state resulting from severe endothelial injury?

Dysfunctional hemostasis Signup and view all the answers

In the context of thrombus development, what is the most significant characteristic of complicated atheroma?

Inflammation and plaque rupture Signup and view all the answers

What is the primary consequence of a cardiac thrombus breaking off?

Embolism leading to myocardial infarction Signup and view all the answers

What term describes the process when a thrombus dissolves and the lumen of the vessel returns to normal?

Dissolution Signup and view all the answers

What does 'propagation' of a thrombus involve?

Thrombus extending along the length of a vessel Signup and view all the answers

Which statement accurately describes a thrombo-embolic disease?

It involves the transport of undissolved material within the vascular system. Signup and view all the answers

In which scenario is recanalization most likely to occur?

When capillaries invade the thrombus Signup and view all the answers

What is the potential fate of a thrombus if it does not dissolve?

It may propagate or lead to recanalization. Signup and view all the answers

What is commonly associated with arterial thrombus formation?

Accumulation of plaque in the arterial wall Signup and view all the answers

What is the definition of an embolus?

A mass of undissolved material transported through the vascular system Signup and view all the answers

Which condition might be directly caused by an arterial thrombus?

Myocardial infarction Signup and view all the answers

Study Notes

Haemostasis

Haemostasis is a physiological response to vessel injury, arresting bleeding.
The process involves three major steps: vasoconstriction, platelet activation, and coagulation cascade activation leading to fibrin clot formation.
The coagulation cascade involves a series of reactions activating clotting factors, changing fibrinogen to fibrin, forming a thrombus.
Fibrinolytic system dissolves the fibrin clot when repair is complete, preventing further damage.

Haemostasis Pathogenesis

Blood contacting tissues activates coagulation cascade.
Coagulation factors convert fibrinogen (soluble) to fibrin (insoluble).
Fibrin threads stick together, forming the thrombus.
Fibrinolytic system (plasmin, plasminogen, fibrinogen lysis) dissolves the clot after repair.

Thrombosis

Thrombosis is the formation of a blood clot (thrombus) within a blood vessel.
Blood clots can form in a test tube or blood vessels after death; blood coagulates in living bodies.
A thrombus is a solid or semi-solid mass in the blood vessel during life.

Thrombosis - Definition of Terms

Blood clots can form in a test tube, in vessels after death, or in living vessels.
A thrombus is a blood clot formed within the vascular system during life.

Thrombosis - Virchow's Triad

Three factors contribute to thrombosis: endothelial injury, abnormal blood flow, and hypercoagulability.
Endothelial injury: trauma, inflammation, atherosclerosis.
Abnormal blood flow: stasis (slow blood flow), turbulence.
Hypercoagulability: increased tendency to clot.

Types of Thrombi

Venous thrombi (phlebo-thrombosis, thrombo-phlebitis): vein inflammation, stasis, post-partum or surgery.
Arterial thrombi: damage to the vessel wall (atheroma, inflammation), altered blood flow (stasis, aneurysm, tumor).
Cardiac thrombi: atria (mitral stenosis), ventricles (myocardial infarction, myocarditis, aneurysm)
Capillary thrombi: disseminated intravascular coagulation.

Fate of a thrombus

Dissolution: the thrombus dissolves, lumen returns to normal.
Propagation: thrombus extends along vessel.
Recanalization: capillaries invade thrombus, re-establishing blood flow.
Organisation: scar tissue replaces thrombus, lumen obliterated.
Embolization: thrombus travels to another site.

Thrombo-Embolic Disease

Embolus is a mass, or undissolved material, traveling through the vascular system causing blockage.
Emboli can arise from thrombotic material.
In most cases, emboli are thrombotic.

Venous Thrombo-Embolic Disease

Deep vein thrombosis (DVT) in lower limbs can embolise to pulmonary trunk (saddle embolus).
Frequent in post-surgical/post-partum patients.
Thrombo-emboli travel through the lungs but do not affect the systemic circulation.

Types of Emboli

Atheromatous thrombo-emboli - thrombotic material mixed with atheromatous debris.
Air/Gas emboli.
Abortions.
Head and neck surgery.
Amniotic fluid emboli post-delivery.
Fat emboli extensive trauma to skeleton.
Tumor emboli.
Foreign bodies/parasites.

Hypoxia

Hypoxia is inadequate oxygen supply to tissues.
Types include ischaemic, hypoxic, anaemic, and histotoxic.

Ischemia and Infarction

Ischemia: inadequate blood supply to tissues.
Infarction: tissue death from ischemia.
Ischemia factors affect severity include: blood supply (double, collateral), rate of onset, vessel occlusion, tissue type (connective tissue is less susceptible), extent of damage.

Classification of Infarcts

Colour: pale (anaemic) or haemorrhagic.
Presence/absence of infection: (septic or bland).
This refers to the microscopic appearance of areas of necrosis.

Case Study

A 52-year-old man with previous myocardial infarction is found to have a mural thrombus in the left ventricle.
This thrombus is a material lodged within the heart chamber wall.

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Description

This quiz covers the physiological processes of haemostasis, including the steps involved in blood clot formation and dissolution. It also delves into thrombosis and the mechanisms behind blood clot formation within vessels. Test your understanding of these critical concepts in vascular biology.