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PLTs
Clin Path
| Question | Answer |
|---|---|
| What is the maturation sequence of a platelet? | PPSC-> Myeloid stem cell-> Megakaryoblast->Megakaryocyte |
| What is the parent cell of the platelet? | Megakaryocyte |
| What is required to stimulate for PPSC to differentiate into megakaryocytes? | TPO- Thrombopoietin |
| What are the 3 main sources of TPO? | liver, endothelial cells and fibroblasts |
| Describe a megakaryocyte. | Large, multinucleated, abundant cytoplasm. Nuclei fuse to resemble a large multilobed nucleus. |
| Where do megakaryocytes reside most commonly? | bone marrow |
| How many PLTs form from a single megakaryocyte? | 1000-5000 |
| What portion of the megakaryocyte break off and enter the bloodstream as PLTs? | infoldings |
| Where are PLTs most commonly stored? | Spleen |
| How long do PLTs survive in circulation in the cat? | 1 day |
| How long do PLTs survive in circulation in the dog? | 5-8 days |
| What is another name for PLT? | thrombocyte |
| What activates a PLT? | Insult or injury to the host |
| What do PLTs lack that would normally classify them as a cell? | nucleus |
| There are more PLTs in the blood than _______ but fewer PLTs than ______. | WBCs; RBCs |
| True or false. PLTs have a greater variety of functions than any of the true blood cells | True |
| Most PLTS are smaller than what other blood cell? | RBC |
| In what species do PLTS stain lighter than other spp? | Horses |
| What color are the granules of a PLT? | pink/purple |
| What shape are PLTs normally? | discoid |
| What type of PLTs are occasionally seen in blood smears and are considered to be more active than smaller PLTs? | Giant PLTs |
| What structure is seen on activated PLTs and makes it easier for PLTs to stick to one another? | dendritic processes |
| What is the range of PLTs seen in dogs? | 200,000-500,000 |
| What is the range of PLTs seen in cats? | 300,000-700,000 |
| What is the range of PLTs seen overall in all spp? | 100,000-800,000 |
| What spp has the lowest of normal concentrations? | horses |
| What spp has the highest of normal concentrations? | cattle |
| What happens to animals if their PLT conc is <10,000-50,000? | Spontaneous bleeding |
| What percentage of bleeding disorders in cats/dogs result from abnormal PLT number? | 90% |
| During a differential count, seeing how many PLTs in a HPF is considered to be adequate? | 8-10 |
| If PLT numbers are lower than 8-10 per HPF what should be suspected? | Clot |
| What 3 things should be done if PLT numbers are decreased on a blood film? | 1-Check body of smear for clumps 2-Check feathered edge for clumps 3-Check blood tube for clots |
| In what spp of animal is PLT clumping common in? | cats |
| PLT clumping is the result of _____________ to draw blood. | needle stick |
| What can occur invitro due to low ratio of anticoagulant to blood? | PLT clumping |
| What type of pattern should be used when doing a PLT estimation? | Embattlement pattern |
| What are the 2 methods of PLT estimation? | Direct and indirect |
| What method of PLT estimation involves counting 10 HPFs, then determining the average and finally multiplying by 20,000? | direct |
| What method of PLT estimation is done by counting every PLT then dividing by 100? | indirect |
| What is the primary function of a PLT? | maintain vascular integrity |
| Thromboxane is an example of what? | vasocontrictor |
| What initiates the process of a PLT plug formation? | damaged blood vessel |
| What are the procoagulants secreted by PLTs? | Factor XII, Factor XIII, PF1, PF2, PF3, and PF4 |
| What is PF? | Platelet factor |
| What is PDGF? | Platelet derived growth factor |
| What do PLTs secrete to help repair damaged vessels? | PDGF |
| What PLT secretion stimulates fibroblasts and smooth muscle to multiply and repair damaged vessels? | PDGF |
| What process stimulates the secretion of TPA? | fibrinolysis |
| What is TPA? | Tissue plasminogen activator |
| What is responsible for converting plasminogen to plasin? | TPA |
| True or false. PLTs are phagocytic. | True |
| What term refers to the arrest or stoppage of blood loss from vessels? | hemostasis |
| The process of hemostasis is dependant on what three things? | Vessel integrity, adequate number of circulating PLTs and presense of adequate coagulation factors |
| What organ is essential to coagulation? | liver |
| Ehler danlos syndrome and Marfan syndrome are examples of what kind of disorders? | collagen |
| What organ synthesizes most clotting factors? | liver |
| What does the liver produce that is essential for vitamin K synthesis? | bile |
| What vitamin is required to form a clot? | K |
| What 4 factors require vitamin k for activation? | II, VII, IX, and X |
| What is the MAIN task of primary hemostasis? | platelet plug formation |
| What are the 3 steps of primary hemostasis? | endothelial response (vasoconstriction), platelet adhesion, and platelet aggregation |
| When do PLTs become activated? | Upon adherring to the normal endothelium |
| Endothelial response = _________________. | Vasoconstriction |
| What term refers to group of PLTs adhereing to each other? | aggregation |
| What is the ultimate goal of secondary hemostasis? | fibrin formation |
| What part of hemostasis is known as coagulation cascade? | secondary hemostasis |
| What encompasses the platelet plug and provides a superstructure for healing? | fibrin |
| What part of hemostasis is intrinsic, extrinsic, and common pathways involved in? | secondary |
| True or false. Intrinsic and extrinsic pathways typically occur simultaneously after injury. | True |
| Factors involved with intrinsic pathway come from what type of source? | Plasma or platelets |
| What factor is embedded in the plasma membrane of most cells and is released by trauma? | Factor III |
| Factors involved with extrinsic pathways come from what type of sources? | those other than blood |
| After how long does clot retraction occur? | ~30 mins |
| What are the 2 nicknames for a clot retraction? | purse string or cinch sack |
| What term refers to any disorder of blood coagulation? | coagulopathy |
| How are coagulopathies categorized? | according to the stage of hemostasis they affect |
| What are the 2 types of coagulopathies? | aquired or genetic |
| Coagulopathies may involve defects or deficits in what three things? | vasculature, platelets or coagulation factors |
| What type of coagulopathies are associated with a single coagulation factor? | genetic |
| What type of coagulopathies are associated with multiple coagulation factors? | acquired |
| What part of the body makes a majority of the clotting factors? | liver |
| What are 2 reasons you should suspect a hemostatic disorder? | (4 total) increased bleeding time after venipuncture, evidence of bleeding into body cavities, family history of bleeding diathesis, or a history of prolonged bleeding |
| Chronic bleeding and prolonged bleeding are clinical signs of what type of hemostasis? | primary hemostasis |
| What are the 2 types of quantitative primary hemostasis? | thrombocytopenia and thrombocytosis |
| What type of parasite destroys platelets? | ehrlichia platys |
| Less than how many platelets is considered to thrombocytopenia? | less than 30,000 |
| More than how many platelets is considered to be thrombocytosis? | more than 1 million |
| What are the 4 causes of thrombocytopenia? | decreased production, increased rate of destruction, activation, and consumption |
| What is thrombocytopenia most commonly caused by? | infectious diseases |
| What are the 3 causes of thrombocytosis? | bone marrow disorders, secondary disorders, and splenic contractions |
| What are the 2 types of qualitative primary hemostasis? | von willebrands disease and thrombocytopathy |
| What carries VWF? | PLT granules |
| What is the test of choice for VWD? | BMBT |
| What is BMBT? | Buccal mucosa bleeding time |
| What breed of dog is the #1 risk for VWD? | Doberman pinscher |
| What condition usually results from defective granules? | thrombocytopathy |
| What is the number 1 cause of thrombocytopathy? | NSAIDs |
| What are 2 acquired vascular causes of bleeding? | scurvy or cushings |
| What are 2 hereditary vascular causes of bleeding? | Ehlers Danlos or Marfan syndrome |
| What type of hemostasis have clinical signs like delayed bleeding, rebleeding, or hematoma formation? | secondary hemostasis |
| What are the 3 acquired defects of secondary hemostasis? | DIC, Hepatic disease, and rodenticide toxicity |
| Name a common active ingredient of rodenticides. | Warfarin, Coumarin, and Dicoumarol |
| What factors require vitamin K for activation? | II, VII, IX, and X |
| What test is used to confirm warfarin toxicity? | OSPT |
| What is OSPT? | One step prothrombin time |
| What is PIVKA? | Proteins induced by vitamin K absence |
| What are the 2 tests of choice for rodenticide toxicity? | PIVKA and OSPT |
| What type of RBCs are seen with DIC? | Schistocytes |
| What are the 3 phases of DIC? | Peracute, acute, and chronic |
| What is another name for the peracute stage of DIC? | hypercoagulable |
| What is another name for the acute stage of DIC? | consumptive |
| What clotting factor is activated by venom? | Factor X |
| Is fibrinogen and PLT counts increased or decreased with DIC? | increased |
| What 2 tests are prolonged with both DIC and liver dysfunction? | PT and PTT |
| How id DIC diagnosed? | three abnormal coagulation test results |
| Administration of what is controversial with DIC? | heparin |
| What are the 3 potential causes of thrombosis? | Changes in vessel wall, changes in blood constituents, and changes in blood flow |
| Saddle thrombus occurs most commonly in what species with what disorder? | felines with hypertropic cardiomyopathy |
| What are the 3 mechanisms that work together to stop the flow of blood? | vasocontriction, platelet plug formation and clotting |
| What are the 2 substances that control vasocontriction within the body? | epinephrine and thromboxane |
| What type of hemostasis is all about vasocontriction and platelet plug formation? | Primary |
| _____________ inhibits the action of thromboxane. | Aspirin |
| PLTs must first adhere to what before becoming activated? | collagen |
| The process of clotting requires what enzyme (responsible for converting fibrinogen to fibrin) | thrombin |
| What is the ultimate goal of secondary hemostasis? | fibrin formation |
| Damage to the tissue stimulates the activation of what factor that also catalyzes the activation of factor X? | tissue thromboplastin |
| What enzyme dissolves clots? | plasmin |
| What type of anticoagulant inhibits the processing of vitamin K? | coumadin |
| What type of anticoagulant inhibits the activity of thrombin? | heparin |
| What are the 2 drugs used to dissolves clots? | TPA and streptokinase |
| What is the drug of choice for dissolving a clot? | streptokinase |
| What condition is caused by a deficiency of any of the clotting factors? | hemophilia |
| 80% of all hemophilics are deficient in what factor? | VIII |
| What substance is essential to the maturation of several clotting factors? | vitamin k |
| How long does the intrinsic pathway take? | 3-6 minutes |
| How long does the extrinsic pathway take? | 15 seconds |
| What type of anticoagulant prevents the conversion of thrombin from prothrombin? | heparin |
| What clotting factor is required for factor X to activate the prothrombin activator? | V |
| What is another name for thromboplastin or factor III? | tissue factor |
| What is another name for proconvertin of factor VII? | stable factor |
| Which clotting factor is carried on VWF? | XIII |
Created by:
fadedfaithless