Blood Clotting, Hemostasis, and Blood Types Vocabulary

Comprehensive vocabulary flashcards covering blood coagulation pathways, hemostasis steps, clot dissolution, anticoagulant factors, clotting disorders, and blood group antigens and antibodies.

Coagulation

The process of blood clotting, involving a complex series of chemical reactions using proteins called clotting factors.

Clotting Factors

Proteins in the blood—identified by Roman numerals indicating their order of discovery—that remain inactive under normal conditions until activated in a reaction cascade.

Reaction Cascade

A series of chemical reactions in which each step depends on the product of the preceding reaction to trigger the next reaction on a set pathway.

Extrinsic Pathway

A clotting cascade initiated when damaged blood vessels and surrounding tissues release clotting factors outside the blood, resulting in clot formation in about $15\text{ seconds}$.

Intrinsic Pathway

A clotting cascade initiated when clotting factors are activated within the blood (such as by platelets adhering to vessel wall collagen), requiring four reactions to activate factor X and taking $3\text{ to }6\text{ minutes}$ to form a clot.

Factor X

A clotting factor activated by both the extrinsic pathway (via a single reaction) and intrinsic pathway (via four reactions) that leads into the common pathway of blood clot formation.

Prothrombin Activator

An enzyme produced as the end result of both the extrinsic and intrinsic pathways that converts prothrombin into thrombin.

Prothrombin (Factor II)

A globulin plasma protein converted into the enzyme thrombin by prothrombin activator.

Thrombin

An enzyme that transforms the soluble plasma protein fibrinogen into fine, insoluble threads of fibrin.

Fibrinogen

A soluble plasma protein that is converted by thrombin into fine threads of insoluble fibrin.

Fibrin

Fine threads of insoluble protein transformed from fibrinogen that create a web to ensnare red blood cells and platelets at an injury site.

Vitamin K

A fat-soluble vitamin absorbed from the intestine in the presence of bile that is required by the liver to synthesize clotting factors.

Fibrinolysis

The process of dissolving a blood clot after a vessel has healed, involving the conversion of plasminogen into plasmin to break up the fibrin meshwork.

Plasminogen

An inactive plasma protein that is converted into plasmin to break down a fibrin blood clot.

Plasmin

An active enzyme converted from plasminogen that works to dissolve the fibrin meshwork of a blood clot.

Heparin

An anticoagulant secreted by basophils and mast cells (or administered by injection) that prevents blood clots by blocking the action of thrombin.

Platelets (Thrombocytes)

Cell fragments of megakaryocytes present at $150{,}000\text{ to }400{,}000\text{ per microliter}$ of blood that live about $7\text{ days}$ and play a key role in hemostasis.

Megakaryocytes

Large bone marrow cells whose edges break off to form cell fragments called platelets.

Hemostasis

The sequence of events that stops bleeding when a blood vessel is cut, consisting of vascular spasm, platelet plug formation, and blood clot formation.

Vascular Spasm

The immediate, temporary constriction of smooth muscle fibers in an injured blood vessel wall to slow the flow of blood.

Platelet Plug

A mass of sticky platelets adhering to exposed collagen and each other to form a temporary seal in a damaged vessel wall.

Thrombus

An unwanted blood clot formed inside an intact or unbroken blood vessel.

Embolus

A piece of a blood clot that breaks off from its origin site and circulates through the bloodstream.

Warfarin (Coumadin)

An oral anticoagulant medication that blocks the effects of vitamin K on the liver, reducing the production of prothrombin.

Hemophilia A

A sex-linked recessive clotting disorder caused by a deficiency of factor VIII, occurring in approximately $1\text{ in }5{,}000$ live male births.

Hemophilia B

A sex-linked recessive clotting disorder caused by a deficiency of factor IX.

Tissue Plasminogen Activator (t-PA)

A substance administered as a drug that stimulates the conversion of plasminogen into plasmin to dissolve clots causing strokes and heart attacks.

Antigen (Agglutinogen)

A protein carried on the surface of cells, such as red blood cells, that allows the body to distinguish its own cells from foreign invaders.

Antibodies (Agglutinins)

Proteins in blood plasma directed against foreign blood antigens that bind to foreign red blood cells and cause them to clump.

Agglutination

The clumping together of red blood cells caused by plasma antibodies binding to antigens on foreign cells.

Hemolysis

The bursting of red blood cells that releases hemoglobin into the bloodstream, which can block kidney tubules and cause renal failure.