Questions and Answers
What is the difference between homeostasis and hemostasis?
Hemostasis is the arrest or stoppage of bleeding, while homeostasis is the process by which variables are regulated to maintain stable internal conditions.
What are the stages of hemostasis?
What is the role of fibrin in blood coagulation?
Fibrin threads attach to the loose platelet plug, blocking the ruptured part of blood vessels and preventing further blood loss.
What are clotting factors?
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Which of the following is a function of plasmin?
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The lysis of blood clot is called _________.
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What type of disorder is hemophilia?
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Clot retraction occurs after blood clot formation.
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What is thrombosis?
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What is the primary substance required for fibrinolysis?
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Study Notes
Difference Between Homeostasis and Hemostasis
- Hemostasis: Arrest or stoppage of bleeding.
- Homeostasis: Regulation of internal conditions to remain stable and constant.
Stages of Hemostasis
- Vasoconstriction: Immediate constriction of blood vessels to reduce blood loss.
- Formation of Platelet Plug: Platelets adhere to collagen at injury sites and release ADP and thromboxane A2.
- Coagulation of Blood: Fibrinogen is converted into fibrin, forming a mesh that stabilizes the platelet plug.
Blood Coagulation
- Coagulation: Process where blood loses fluidity and forms a jelly-like mass after shedding.
- Clotting Factors: Thirteen identified factors necessary for clotting, named after scientists or their functions, except for Factor IX (Christmas factor).
Sequence of Clotting Mechanism
- Clotting occurs through enzyme cascade theory where proenzymes convert to active enzymes in a series of steps.
- Three main stages: Formation of prothrombin activator, conversion of prothrombin to thrombin, conversion of fibrinogen to fibrin.
Blood Clots
- Definition: Mesh of fibrin entangling red blood cells (RBCs), white blood cells (WBCs), and platelets.
- Clot Retraction: Contraction of the blood clot occurring 30-45 minutes post-formation; serum oozes out.
Fibrinolysis
- Definition: Breakdown of blood clots within blood vessels.
- Involves plasmin, which dissolves fibrin threads and allows reopening of blood vessels to prevent issues like myocardial infarction.
Anticlotting Mechanism
- Intravascular clotting prevention is aided by physical (blood circulation, smooth endothelial lining) and chemical factors (heparin, thrombomodulin).
Anticoagulants
- Substances that prevent or delay blood coagulation.
- Types:
- In vivo: Anticoagulants act within the body.
- In vitro: Anticoagulants for collected blood.
- Both: Act in vivo and in vitro.
Bleeding Disorders
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Types:
- Hemophilia: Sex-linked condition causing prolonged clotting times; primarily affects males.
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Purpura: Prolonged bleeding time with normal clotting time; features spontaneous skin bleeding leading to purpuric spots.
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Types of Purpura:
- Thrombocytopenic Purpura: Caused by platelet deficiency due to bone marrow issues.
- von Willebrand Disease: Deficiency in von Willebrand factor affecting platelet adherence.
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Types of Purpura:
Thrombosis
- Definition: Coagulation of blood within blood vessels.
- Can lead to:
- Thrombus: Solid mass obstructing blood flow.
- Embolism: Detachment of thrombus part that can block smaller vessels, with significant effects if it occurs in lungs, brain, or heart (coronary embolism).
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Description
This quiz explores the critical concepts of hemostasis and coagulation of blood, including their differences and the stages involved. Understand the mechanisms that stabilize blood flow after vessel injury and the physiological processes at play. Test your knowledge on this essential topic in physiology.
