Hematology Exam 6 Flashcards by Amber Wilder

Vascular integrity and platelets forming a primary, temporary plug are a part of ________ coagulation.

Primary coagulation

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Plasma coagulation factors are a part of _________ coagulation

Secondary coagulation

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Blood fluidity is dependent on the fibrin lysing system and _______ to coagulation in order to prevent excess clot formation

Inhibitors

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What are the other names for Factor III?

Tissue factor
Tissue thromboplastin

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Rare condition producing abnormal connective tissue and poor support

Telangiectasia

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Is telangiectasia an inherited or acquired vascular disorder?

Inherited

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Type of vascular disorders that may damage endothelial cells or connective tissue

Acquired vascular disorders

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Blood pressure cuff at 80mmHg for 5 minutes then taken off to count petechiae present in a 3 square centimeter area

Tourniquet test

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Normal platelet range

150,000-450,000/mm³

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What percentage of platelets are reserved in the spleen?

33%

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Maturation of megakaryocytes include what 3 stages?

Megakaryoblast
Promegakaryocyte
Megakaryocyte

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What influences the multi-potential stem cell to produce megakaryocytes?

CSF-MEG and thrombopoietin

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66% of platelets cirtculate how many days before the spleen destroys them?

5-10 days

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New terminology for the peripheral zone of a platelet

Platelet plasma membrane

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New terminology for the structural zone of a platelet

Platelet cytoskeleton

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What is the bilayer plasma membrane of a platelet composed of?

-Phospholipids and cholesterol

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Purpose of cholesterol in the bilayer of the plasma membrane of a platelet

Stability, fluidity, transmembranous passageway

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What is the fluffy outer coat that contains factors for adhesion and aggregation on platelets known as?

Glycocalyx

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Glycoprotein that allow platelet to adhere to collagen

GP Ia/IIa

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Glycoprotein that allows platelet to bind to vWF

GP Ib/IX/V

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Glycoprotein that allows binding of fibrinogen to vWF

GP IIb/IIIa

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Part of the platelet that acts as a barrier and regulates metabolic function

Plasma membrane

(aka Peripheral zone)

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This section of the platelet is where the “inside/outside” response occurs

Platelet cytoskeleton

(aka structural zone)

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What are the mcirofilaments in the platelet cytoskeleton composed of?

Actin

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Purpose of actin in the platelet cytoskeleton

Anchors the plasma membrane glycoproteins

Section of the platelet that enables it to store additional quantities of hemostatic proteins found in the glycocalyx

Surface Connected Canalicular System (SCCS)

This part of the platelet sequesters calcium and bears enzymes that support platelet activation

Dense tubular system

Enzymes found in the dense tubular system (3)

- Cyclooxygenase - Thromboxane synthetase - Phospholipase A₂

What section of the platelet is known as the control center for platelet activation?

Dense tubular system

What are the 2 major types of granules in platelets?

- Dense - Alpha

Which platelet granules contains ADP, ATP and Ca²⁺?

Dense granules

These platelet granules contain Factor V, Fibrinogen, vWF, and plasma coagulation activation factors such as HMWK

Alpha granules

Which platelet granules will migrate to the plasma membrane and release their contents directly into plasma upon activation?

Dense granules

Alpha platelet granules will fuse to which part of a platelet when activated and release their contents?

SCCS (Surface connected cannalicular system)

4 Main functions of platelets

- Adhesion - Shape change - Aggregation - Secretion

What stimulates the formation of thromboxane A₂?

Arachidonic acid

A platelet count below what number will cause spontaneous bleeding?

Less than or equal to 10,000/µL

Which platelet test involves a shallow cut made on the forearm and then time is measured regarding the amount of time it takes for the site to stop bleeding when constant pressure in applied via a BP cuff at 40mmHg?

Bleeding time

Examples of primary disorders that cause a quantitative defect resulting in a high platelet count (4)

Myeloproliferative disorders such as: - Polycythemia vera - Chronic myeolcytic leukemia - Myelofibrosis with myeloid metaplasia - Essential thrombocythemia

Examples of secondary disorders that cause a quantitative defect resulting in a high platelet count (3)

- Inflammation - Iron deficiency - Acute blood loss

Aplastic anemia, megaloblastic anemia, marrow infiltraion by malignant cells, and chemotherapy would all cause quantitative platelet defects resulting is ___________ (low/high) platelet counts.

LOW platelet counts

- Increased platelet destruction due to an autoantibody to platelets - Fairly common - May be acute or chronic - Acute is seen in children following infection - Chronic is often seen in women of child-bearing years

Idiopathic Thrombocytopenia Purpura (ITP)

Quantitative platelet defect: - Ages 2-6 years - Platelet count \<20,000/uL - Petechiae are common - Following a viral infection such as rubella, chickenpox, CoV-19 - Antibody produced against viral antigens bind to the platelet surgace causing destruction of platelet

Acute ITP

TRUE or FALSE: Acute ITP is typically self-limiting and will resolve itself

TRUE

Quantitative platelet defect: - Ages 20-40 years old - Onset is gradual - Platelet count 30,000-80,000/uL - More common in females

Chronic ITP

Heparin and quinidine are drugs that cause increased platelet destruction due to actings like ______ which eleicit an antibody response | (Think immunology)

Haptens

Platelets contain more of which major type of granule?

Alpha granules (50-80 per platelet)

Which glycoprotein will vWF bind to on a platelets surface to make the platelet adhere reversibly to the vessel wall?

Glycoprotein Ib

Exposure to collagen and ADP being secreted will cause platelets to do what?

Platelets will change shape from discoid to a spiny sphere with pseudopods

For platelet aggregation, what glycoprotein will fibrinogen bind to?

Glycoprotein IIb-IIIa

What is produced during secondary aggregation?

An irreversible plug

What is produced by plasma clotting factors in order to reinforce the irreversible platelet plug to stop bleeding?

Fibrin

3 different platelet tests

- Platelet count - Bleeding time - Platelet aggregation

Which platelet test checks platelet count as well as vascular integrity?

Bleeding time

What are the commonly usecd aggregating agents in platelet aggregation studies?

Epinephrine, ADP, Collagen, and Ristocetin

Antibodies produced against viral antigens (chickenpox, rubells, etc.) bind to the platelet surface causing the platelet to be destroyed

Acute ITP

What 2 drugs act as haptens and elicit an antibody response creating an antigen-antibody complex that attaches to the platelet surface causing the platelet to be removed from circulation?

Heparin and Quinidine

What are the 3 most common causees of increaased platelet destruction due to non-immune destruction?

- Thrombotic Thrombocytopenic Purpura (TTP) - Hemolytic Uremic Syndrome (HUS) - Disseminated Intravascular Coagulation (DIC)

Best way to tell the difference between ITP and TTP?

Neurological symptoms are seen with TTP and not with ITP

How is TTP treated?

Plasma exchange - Remove ULVWF - Replace with fresh frozen plasma (FFP) or cryoprecipitate poor plasma As well as corticosteroids

Which platelet disorder is missing ADAMTS-13?

Thrombotic thrombocytopenic purpura

Purpose of ADAMTS-13

Cleaves the ULVWF (ultra-large vonWillebrand Factor) multimers into smaller vWF multimers

In the absence of ADAMTS-13, ULVWF will bind to which platelet glycoproteins?

GP Ib and GP IIb/IIIa

ULVWF binding to GP Ib and GP IIb/IIIa causes (increased/decreased) adhesion and aggregation which forms hyaline thrombi

Increased

Name the platelet disorder: - Decreased platelet count - Schistocytes seen on PB smear - Decreased haptoglobin - Increased LDH and Bilirubin - Normal PT, PTT, Fibrinogen, FSPs, and D-Dimer

TTP

This is found only in children following an infection, typically with either Salmonella or E coli.

HUS Hemolytic Uremic Syndrome

How are HUS and TTP differentiated?

TTP has neurologic symptoms as well as usually having a more severe thrombocytopenia In HUS the platelet consumption is usually occurring in the kidneys

Clotting occurs throughout the whole body. Increased PT, PTT, FSP, and D-Dimer Decreased platelet count and Fibrinogen

DIC Disseminated Intravascular Coagulation

Types of qualtitative platelet defects (3)

- Adhesion - Aggregation - Secretion

Most common adhesion defects (2)

- Von Willebrand's Disease - Bernard-Soulier Disease

Defective glycoprotein Ib causing an inability to bind to vWF. Patients exhibit hemorrhage characteristics (expanding large hematomas)

Bernard-Soulier Disease

Low, absent, or defective VIII:vWF causing defective platelet adhesion

Von Willebrand's Disease

Aggregation platelet defect due to a defective glycoprotein IIb/IIIa. Causes aa inability to bind fibrinogen and form bridges for aggregation

Glanzmann's