Self-Evaluation: Platelets and Primary Hemostasis

Secondary hemostasis

Activation of coagulation proteins

Sites of bleeding in patients with thrombocytopenia are usually: deep muscle tissues external skin and mucous membranes joints all of the above

external skin and mucous membranes

A patient with a platelet count of 16 x 109/L might have which of the following symptoms? petechiae intracranial bleeding profuse bleeding from cuts in the skin all of the above

petechiae intracranial bleeding profuse bleeding from cuts in the skin all of the above

Aggergation

When forming the primary hemostatic plug, _________________ requires fibrinogen and the fibrinogen receptor.

Adhesion

When forming the primary hemostatic plug, _________________ requires von Willebrand factor and its receptor.

Which platelet count is consistent with thrombocytosis? 200 x 10^9/L 20 x 10^9/L 2000 x 10^9/L 2 x 10^9/L

2000 x 10^9/L

Which of the following are platelet agonists? endothelial cells and collagen prostacyclin and nitric oxide ADP, collagen, and thrombin von Willebrand factor and glycoprotein Ib

ADP, collagen, and thrombin

Glanzmann's Thrombasthenia

Absence or decrease of GPIIb/IIIa complex

NAIT

Antibodies directed against platelet antigens of a newborn

Acute ITP

Antibody to patient's own platelets. Affects age 2-4 with spontaneous remission.

Chronic ITP

Antibody to patient's own platelets. Occurs more in females age 20-50. Diagnosis of exclusion.

Platelet Aggregation Pattern: ADP and EPI = Primary wave; AA = suppressed response

Aspirin ingestion

TXA2

Aspirin results in irreversible inactivation of the platelet enzyme cyclo-oxygenase and inhibition of _________________ synthesis for the life of the platelet. This means there will be no secretion of platelet granules.

A patient with a severe nosebleed was seen in the emergency room of your hospital. When performing the evaluation of the peripheral blood smear, you noticed that at least 75% of the platelets were large or giant size. The platelets had abnormal morphology and appeared to have a large complement of granules. What condition may this patient have? Glanzmann's thrombasthenia essential thrombocythemia Bernard-Soulier syndrome Uremia

Bernard-Soulier syndrome

Platelet Aggregation Pattern: ADP, EPI, and Collagen = normal; Ristocetin and Ristocetin + vWF = no response

Bernard-Soulier syndrome

Test that measures platelet number and function. Lancet produces a standard wound that is blotted with filter paper until bleeding stops. PFA has replaced this test.

Bleeding time (Duke and Ivy methods)

Ecchymoses

Bruise greater than 3mm

Primary hemostatic plug

Clump of platelets that temporarily arrest bleeding

Bernard-Soulier syndrome

Decrease or abnormal function of GPIb/IX complex

Storage Pool Deficiencies

Defect of platelet granules.

Fibrinolysis

Digestion of fibrinogen and fibrin by plasmin

Platelet Aggregation Pattern: ADP, EPI, and Collagen = no response

Glanzmann's Thromasthenia

Secondary hemostatic plug

Hemostatic plug reinforced with insoluble fibrin

Which of the following is an acquired vascular disorder? hereditary hemorrhagic telangiectasia acute immune thrombocytopenia Henoch-Schoenlein purpura Marfan's syndrome

Henoch-Schoenlein purpura

Ehlers-Danlos syndrome

Hyperdistensible joints and skin

Uremia

Increased BUN causing plt dysfunction

Primary hemostasis

Interaction of platelets and vascular endothelium to stop bleeding following vascular injury

Thrombopoietin TPO

Platelet development is regulated by the hormone __________________.

The PFA must have a certain platelet count and hematocrit in order to produce accurate results. What must these values be?

Plt = 150, Hct = 35

von Willebrand Disease

Plt aggregation has no response with ristocetin. Increased PTT due to decreased factor VIII.

Purpura

Purple discoloration of skin 1 cm or greater

HIT

Recurrent thrombosis while on heparin

Petechiae

Small pinhead dots caused by blood escaping from capillaries

Hereditary Hemorrhagic Telangiectasia

Small vascular malformation of skin and mucous membranes

Platelet Aggregation Pattern: ADP and EPI = Primary wave; Ristocetin and AA = normal response

Storage pool disease

Structural

The cytoskeleton and contractile region of the platelet are located in the _________________ zone.

150-400

The normal concentration of platelets in the peripheral blood is about ___________ K/cmm.

PF3

This platelet factor is a phospholipid that allows for the assembly of vitamin K-dependent coagulation factors.

PF4

This platelet factor neutralizes heparin on the endothelial surface and promotes coagulation.

Post-Transfusion Purpura

Thrombocytopenia about 1 week after a platelet transfusion

Test that measures vascular integrity. Still used to diagnose Dengue infection

Tourniquet test or Rumpel-Leede

GPIIb/IIIa

_________________ is the platelet receptor for fibrinogen

GPIb/IX

_________________ is the platelet receptor for von Willebrand factor

Endomytosis

_________________ is when the nucleus undergoes multiple divisions with no cytoplasmic separation.

The parent compound from which thromboxane A2 is formed in the activated platelet is: ADP thrombin arachidonic acid von Willebrand factor

arachidonic acid

Vasoconstriction is a function of: platelets blood vessels erythrocytes hemostatic proteins in the plasma

blood vessels

In primary hemostasis, von Willebrand factor (VWF) functions as a(n): bridge between platelets and collagen in the subendothelium platelet agonist trigger for platelet "shape change" inhibitor of platelet aggregation

bridge between platelets and collagen in the subendothelium

Platelet aggregation is the process of: platelets binding to collagen platelets causing vasoconstriction platelets binding to one another platelets binding to endothelial cells

platelets binding to one another

Platelet Aggregation Pattern: ADP, EPI, Collagen, and Ristocetin + vWF = normal

von Willebrand disease