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Questions and Answers
What is thrombosis primarily defined as?
What is thrombosis primarily defined as?
Which of the following is NOT a cause of endothelial injury leading to thrombosis?
Which of the following is NOT a cause of endothelial injury leading to thrombosis?
Which condition is associated with hypercoagulability due to an acquired cause?
Which condition is associated with hypercoagulability due to an acquired cause?
What is a common characteristic of ischemia?
What is a common characteristic of ischemia?
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What role do coagulation factors play in thrombosis?
What role do coagulation factors play in thrombosis?
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What type of obstruction is characterized by sudden and complete interruption of arterial blood supply?
What type of obstruction is characterized by sudden and complete interruption of arterial blood supply?
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Which of the following is NOT a cause of acute ischemia?
Which of the following is NOT a cause of acute ischemia?
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Which statement regarding chronic ischemia is true?
Which statement regarding chronic ischemia is true?
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What effect can good collateral circulation have on tissue during acute ischemia?
What effect can good collateral circulation have on tissue during acute ischemia?
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What tissue type is particularly vulnerable to hypoxia and may rapidly undergo necrosis when blood supply is cut off?
What tissue type is particularly vulnerable to hypoxia and may rapidly undergo necrosis when blood supply is cut off?
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What causes thrombophlebitis?
What causes thrombophlebitis?
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Which type of thrombus consists only of platelets?
Which type of thrombus consists only of platelets?
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Which of the following describes a mixed thrombus?
Which of the following describes a mixed thrombus?
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What is the primary cause of phlebothrombosis?
What is the primary cause of phlebothrombosis?
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What is a septic thrombus likely to cause?
What is a septic thrombus likely to cause?
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Study Notes
Disorders of the Circulatory System
- Circulatory disturbances include thrombosis, embolism, and ischemia.
- Thrombosis is the formation of a thrombus (solid mass) from circulating blood inside the cardiovascular system.
- Embolism involves blockage of a blood vessel by an embolus (insoluble solid, liquid, or gaseous mass) transported from its origin to a distant site.
- Ischemia refers to reduced or blocked blood supply to tissues.
Virchow's Triad
- Virchow's triad describes the three main factors contributing to thrombosis:
- Blood flow abnormality (stasis or turbulence)
- Endothelial cell dysfunction/injury
- Hypercoagulable state
Causes & Pathogenesis of Thrombosis
- Endothelial injury is a major cause of thrombosis, acting alone or in combination with other factors that activate platelets and the coagulation cascade.
- Causes of endothelial injury include mechanical factors (trauma, ligature, pressure), degenerative changes (atherosclerosis, aneurysm), and inflammation (arteritis, endocarditis, phlebitis).
- Abnormal blood flow (stasis or turbulence) disrupting laminar flow and bringing platelets into contact with the endothelium. Activating platelets and clotting factors.
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Hypercoagulability is an imbalance in the balance of bleeding and clotting factors.
- Acquired factors include increased RBCs (polycythemia), WBCs (leukemia), platelets (postoperative), fibrinogen (late pregnancy, lobar pneumonia), and decreased plasma (post-hemorrhage, dehydration, persistent vomiting, diarrhea).
- Inherited factors include mutations in factor V and prothrombin genes that increase their activities.
Types of Thrombi
- Platelet thrombi are formed only from platelets, are weak and pale, easily washed away by normal blood flow.
- Mixed thrombi contain platelets, fibrin network, RBCs, and WBCs. They are larger and more stable.
- Propagating thrombi spread inside the blood vessel until they reach an area of normal blood flow.
Classification of Thrombosis
- Thrombi can be categorized by color (pale, red, or mixed), size (occlusive or non-occlusive), and presence of infection (septic or aseptic).
- Sites of thrombosis include heart, arteries, veins, and capillaries. Specific examples of sites mentioned are phlebothrombosis and thrombophlebitis.
Thrombophlebitis & Phlebothrombosis
- Thrombophlebitis is thrombosis in inflamed veins. Causes include inflammation due to endothelial injury, and less common causes (septic - bacteria, non-septic - irradiation).
- Phlebothrombosis is thrombosis in non-inflamed veins. Causes include stasis and hypercoagulability.
Fate of Thrombi
- Aseptic thrombi can undergo lysis/resolution, fragmentation, organisation and recanalization, and calcification.
- Septic thrombi fragment and form septic emboli, which can lead to multiple pyemic abscesses.
Clotting
- Clotting is a process where blood loses its fluidity and forms a jelly-like mass.
- Causes include stasis and activation of the coagulation cascade.
- Inside the cardiovascular system (living), clotting happens through a process of thrombosis. Outside of the cardiovascular system (after death) clotting may follow a different pathway.
Embolism
- Embolism is the blockage of blood vessels by an embolus.
- Emboli are insoluble solid, liquid, or gaseous masses carried by the blood to a distant location.
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Causes & Types of Embolism:
- Detached thrombi (thrombo-embolism): Most common.
- Fat embolism: Fat from bone marrow after bone fracture entering the circulation.
- Air embolism: Due to injury of neck or chest veins.
- Parasitic emboli: (e.g., bilharzial worms, ova).
- Tumor emboli: Tumour cells penetrating blood vessel walls.
- Amniotic fluid embolism: During labor.
Ischemia
- Definition: Cutting off of arterial blood supply to tissues.
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Types:
- Acute ischemia: Sudden and complete obstruction of artery. Causes: thrombus, embolus, surgical ligature, ergot poisoning, twisting of vessels, frostbite.
- Chronic ischemia: Gradual and incomplete obstruction of artery. Causes: atherosclerosis, compression from outside (enlarge lymph nodes, gravid uterus, tumors).
- Effects: Good or bad collateral circulation. Good collaterals lead to degeneration of tissues where blood supply is limited due to smaller number of cells. Bad collaterals lead to necrosis.
Additional Notes
- Quiz Time questions include components of Virchow's triad and types of emboli for further study and evaluation.
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Description
Explore the complexities of circulatory system disorders such as thrombosis, embolism, and ischemia. Understand the causes and mechanisms behind these conditions, including Virchow's triad and endothelial injuries. Test your knowledge with this informative quiz.
