Unit 5 Flashcards by Macey Knutson

What does primary hemostasis include

Platelet production, destruction, function

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What is Secondary Hemostasis

Coagulation cascade
Fibrinolysis

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What is a clot

Soluble protein fibrinogen converts to insoluble fibrin

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What does a clot do

Reinforces platelet plug

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What is fibrinolysis

Dissolution of the fibrin clot

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What does hemostasis depend on

1.Structure and integrity of blood vessels
2.Platelet concentration and function
3.Clotting factors

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What are the 3 layers of tissue in blood vessels

Tunica Intima
Tunica Media
Tunica Adventitia

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What is the Tunica Intima

-A continuous, single layer of flattened epi cells
-Provides a protective environment for cellular elements of blood

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What is Tunica Media

Composed of smooth muscle cells that can contract or expand to dilate or constrict lumen

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What is Tunica Adventitia

Composed of collagen-anchors vessels to surrounding tissues

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Why are normal epi cells negatively charged

Repel platelets and clotting proteins

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What do injured Epi cells produce

-von Willebrand Factor
-Platelet activating factor

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What does VWF do

-Aids in platelet adhesion to injured sites
-Carries a certain clotting protein (VIII)

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What does exposure of tissue factor do

Exposes the receptor for clotting factor VII and will initiate the extrinsic coag pathway

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Why are injured epi cells thrombogenic

with collagen exposure they become sticky which creates contact activation

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what is contact activation

a protein complex forms on collagen which initiates the intrinsic coag pathway

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What do blood vessels do after an injury

VASOCONSTRICTION
1. narrow the lumen to reduce blood loss
2. force platelets and plasma proteins into closer proximity to the vessel wall
3. stimulate and prolong platelet release of serotonin

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What happens in Primary Hemostasis

Platelets:
-Adhere to injured vessel wall
-Aggregate to each other
- Form the primary hemostatic plug

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How do mature MKs mature

Endomitosis

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What is endomitosis

-Doubling of nuclear DNA content without dividing
-increase in cell size
-single nucleus goes from a round to highly lobulated nucleus

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1 megakaryocyte = how many platelets

1,000-3,000

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What is TPO

Thrombopoietin

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What does TPO do

-Major factor regulating platelet development
-Influences MK and platelet production

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Where is TPO produced

At a constant rate primarily in the liver

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How does TPO work

Binds to MKs and MK precursors and stimulate Binds to circulating platelets (prevent excessive production)

What is a result of an increased level of free active TPO

Thrombocytopenia

Normal reference range for PLT

150-450

How long do PLTs survive

9-12 days

What does GP-Ib do

Adheres PLT to damaged vessel Major receptor for VWF

What does GP-IIb/IIIa do

Aggregates surrounding PLTs Major receptor for fibrinogen

What do alpha granules of PLTs contain

Hemostatic proteins: Clotting factors VWF Non-hemostatic proteins: Growth factors for wound healing

What do dense bodies of PLTs contain

Serotonin *induce/prolong vasoconstriction Platelet aggregation agonists *non-metabolic ADP *Epinephrine Calcium *important for secondary hemostasis

What are the strong agonists for PLTs

Collagen Thrombin

What is collagen used for in PLTs

Exposed upon vascular injury *VWF binds to collagen *PLT GP-Ib binds to VWF (adhesion)

What does Thrombin used for in PLTs

Tissue Factor is exposed upon vascular injury *Small amounts of thrombin are produced *Thrombin attracts and activates PLTs *Activated PLTs amplify thrombin production *Leads to a stabilized fibrin clot

Platelet-derived Agonists can produce what other substances upon activation

Thromboxane A2 (TxA2) Platelet activating factor (PAF)

What do PLT-derived agonists release from their granules

ADP Epinephrine Serotonin

What does aspirin do

COX inhibitor which prevents PLT aggregation

How is Thromboxane A2 produced

-COX catalyzes the conversion of Arachidonic acid into Prostaglandin H2 -Prostaglandin H2 is then converted to TXA2

What does TXA2 do

activates GP IIb/IIIa which promotes PLT aggregation

What does VWF carry

Clotting Factor VIII

What step of PLT function requires Calcium

Aggregation

What does fibrinogen do

Acts like a bridge and connects adjacent platelets

What does In Vivo testing for

bleeding time

What In Vitro testing for

platelet function analyzer

platelet function analyzer (PFA) detects what

Closure time: the amount of time it took for the PLT plug to form

The 3 pathways in 2nd Hemostasis

Intrinsic Extrinsic Common Pathway

What is evaluated in In Vitro testing

PT aPTT TT

What does PT evaluate

extrinsic and common pathway

What does aPTT evaluate

intrinsic and common pathway

What doe TT evaluate

Common pathway

What is a zymogen

Inactive form of an enzyme

What produces zymogens

mostly the liver

What Coag Factors are in the intrinsic pathway

PK HK XII XI IX VIII

What are the names for PK

Prekallikrein Fletcher Factor

What are the names for HK

High Molecular Weight Kininogen Fitzgerald Factor

What is the common name for XII

Hageman Factor

What is the common name for XI

Antihemophilic Factor C

What is the common name for IX

Antihemophilic Factor B Christmas Factor

What is the common name for VIII

Antihemophilic Factor A **carried in circulation by VWF

What are the contact factors

PK HK XII XI

What activates Contact Factors

Collagen when exposed

What is in the extrinsic pathway

Tissue Factor VII

What is tissue factor also known as

thromboplastin

What makes up Extrinsic Tenase

VIIa:Ca2+

What does extrinsic tenase do

Assembles TF expressing cells Activate IX

What is Factor X also known as

Stuart-Prower Factor

What is Factor V also known as

Labile Factor

What factor deteriorates at room temperature

Factor V: Labile Factor

What is Factor II

Prothrombin

What is the active form of Factor II

Thrombin

What is Factor I

Fibrinogen

What is the active form of Factor I

Fibrin

What makes up Prothrombinase

Xa Va Ca2+ PL (phospholipid)

What is Fibrinogen

Acute phase protein synthesized by the liver

What is the role of fibrinogen

Acts a bridge between aggregated platelets Precursor to fibrin mesh

What are the 3 stages of conversion of fibrinogen to fibrin

1. Proteolysis 2. Polymerization 3. Stabilization

What happens in Proteolysis

Cleavage of Factor I into active Ia by thrombin Results in fibrin monomer

What happens in Polymerization

Spontaneous self-assembly into fibrin polymers

What happens in stabilization

Intro of covalent bonds into fibrin polymers by XIIIa

What will create the stable, crosslinked fibrin clot

Zymogen Factor XIII

What activates XIII

thrombin

What are the roles of thrombin

Activates: Fibrinogen, VIII, XIII Stimulates endothelial cells to release VWF A platelet agonist

What is the sequence after vessel injury

Vasoconstriction Platelet adhesion Platelet aggregation Coagulation cascade Fibrin Stabilization

What are the Vitamin K dependent factors

II VII IX X

What does Vit K do

y-carboxylation of glutamic acid Adding carboxy group to negatively charged phosohlipid membrane via Ca2+

What does Coumadin inhibit

Activity of epoxide reductase and prevents Vit K function

How does Coumadin affect Vit K

Proteins are synthesized y-carboxylation does not occur Clotting factors can't bind to phospholipid surface via Ca2+ Rendered nonfunctional

What are naturally occurring inhibitors

Antithrombin Tissue factor pathway inhibitor Protein C & S

Unit 5 Flashcards

(89 cards)