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Heme II Test 4
Terms in this set (53)
What is the most likely factor deficiency for a patient having an increased PT?
What are the platelet receptors?
Glycoproteins on the platelet surface
• GPIb-IX and GPIIb/IIIa • The platelet membrane contains important receptors (glycoproteins) on the platelet surface. Further interactions are mediated by plasma protein vWF and fibrinogen. vWF receptor is GPIb-IX whereas GPIIb/IIIa are the receptors for fibronectin (pg. 237)
List the regulatory molecules associated with vasoconstriction.
Thromboxane A2 & Serotonin
List the factors that are vitamin K-dependent.
2, 7, 9, 10, protein C & S
What is the life span of a platelet?
7 to 10 days
Alpha granules are found in which platelet zone?
Organelle zone: alpha, dense bodies, and lysozymes
What coagulation factors are produced in the liver?
Coagulation factors are produced in the liver, which the exception of a portion of Factor VIII, which is produced in the endothelial cells
List the major coagulation inhibitors.
1.)Heparin - activates AT III
2.) Proteins C & S -inactivate Factor VIII (as well as V)
3.) Antithrombin III -inactivates 12, 11, 9 (as well as 10 & 2)
4.)Vitamin K deficiency -Factor IX is Vit K dependent
What is the sample time stability for PTT? For PT? What is the storage requirement for longer stability?
1.) 4 hours PTT and 24 hours PT room temperature
2.) Plasma can be removed from the sample and stored @ -20 degrees Celsius for 2 weeks
The most important kinin. Dilate small blood vessels, induces inflammation, chemical pain mediation, vascular permeability, and contract smooth muscle.
Define primary hemostasis.
The interaction of platelets and the vascular endothelium in halting bleeding following vascular injury.
Define secondary hemostasis.
to prevent re-bleeding by stabilizing the clot. This is done by covering it with a fibrin mesh that prevents clot breakdown
What mediates platelet aggregation?
von Willebrand factor (vWF) and platelet glycoprotein Ib (GPIb)
List the four phases of platelet functions at the site of injury
Adhesion, aggregation, release, stabilization
What test monitors the intrinsic pathway? List the factors of the intrinsic pathway.
PTT, Factors VIII, IX, and XII and common pathway (I,II,V, and X)
What test monitors the extrinsic pathway? List the factors of the extrinsic pathway.
PT, Factors VII and X
What does PT and PTT have in common?
What test is needed to obtain the INR value?
Prothrombin Time (PT):
INR is the ratio of a patient's prothrombin time to a normal (control) sample, raised to the power of the ISI value for the analytical system used.
What are mixing studies?
is to determine if a prolonged PTT or PT is due to a deficiency or to an inhibitory antibody
Acute ITP (Idiopathic Thrombocytopenic Purpura)?
•platelet count as low as 20,000
•age usually 2 - 6 years
•often caused by virus (rubella, rubeola, or chickenpox)
•lasts 2 - 6 weeks
•platelet count 30,000-80,000 /L
•age 20-50 years
•lasts months to years
Name the three adhesion disorders and list their deficiencies
1.)von Willebrand's Disease-Factor VIII (vWF)
2.)Bernard-Soulier Syndrome-GPIb-IX complex
3.)Glanzmann's Thrombosthenia-GPIIb and GPIIIa
Name three essential elements in the hemostatic system.
Vascular spasm, platelet plug, coagulation (blood clotting)
ADAMTS13 deficiency is responsible for thrombocytopenia in which disorder?
thrombotic thrombocytopenic purpura-This protein is responsible for cleaving large multimers of vWF
What is a normal platelet count?
What is the bleeding time test used for?
screening test for platelet disorders and von Willebrand's disease. Affected by the platelet count and the ability of platelets to form a plug. Reference ranges: 2-9 minutes using simple methodology
What is the significance of thromboxane A2?
At the site of injury the vasoconstrictor substance is released from the platelets (Potent inducer of platelet aggregation)
What does penicillin, ampicillin, aspirin, and ibuprofen have in common?
All affect platelet function(drug-induced thrombocytopenia)
What is NAIT?
Neonatal Alloimmune Thrombocytopenia-Result of a maternal antibody made from a previous exposure to platelet antigens from an earlier pregnancy.
What is PTP?
When a recipient's blood has an antibody that reacts against a transfusion containing the primary platelet antigen
What is the correct anticoagulant-to-blood ratio for coagulation?
What is the anticoagulant of choice for routine coagulation ?
What test is normal for a patient with von Willebrand's disease?
presence of thrombocytopenia and giant platelets on peripheral smear
irreversible inactivation of platelets
severe deficiency of dense granules
deficiency of alpha granules
X-linked recessive disorder
Ristocetin co-factor activity
is the best predictive assay for von Willebrand factor
Glanzmann thrombasthenia individuals
umbilical or circumcision bleeding
Platelet aggregation is dependent on
Fibrinogen is the main substrate of
Factor V is measured
both PT and PTT
Vasoconstriction is the first response
of a cut vessel
List coag factors for fibrinogen group.
I, V, VIII, XIII (1,5,8,13)
List coag factors for prothrombin group.
II, VII, IX, X (2,7,9,10)
List coag factors for contact group.
XI, XII, prekallikrein, high molecular weight (HMWK,11,12)
Factor VIII (8) is deficient in
Factor IX (9) is deficient in
hemophila B, also known as Christmas disease
Factor XIII (13) not measured by
PT or PTT- screening results would be normal
Inhibits thrombin activity
When blood cells clot, the fibrinogen of the plasma converts to what?
Fibrin by the action of Thrombin
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