Hemostasis 2

Question 1

what is the end result or goal of coagulation?

Answer 1

formation of thrombin and convert fibrinogen into fibrin

Question 2

the intrinsic pathway is initiated by

Answer 2

exposure of collagen or activated platelet surface, or in vitro it would be glass or silica particles

Question 3

the extrinsic pathway is initiated by

Answer 3

tissue factor (TF), a membrane protein released from damaged cells

Question 4

exstrinsic refers for a _____

Answer 4

need of an extravascular protein as the clotting trigger

Question 5

the common pathway ultimately leads to the formation of

Answer 5

thrombin, which conerts fibrinogen to fibrin

Question 6

In vivo, the ______ is believed to be most important in initiating coagulation and involves 3 overlapping phases as opposed to a cascade of reactions

Answer 6

extrinsic pathway

Question 7

the propagation phase of coagulation is caused by:

Answer 7

thrombin burst

Question 8

what do the following stand for:
- ACT
- PT
- aPTT

Answer 8

• activated clotting time
• prothrombin time
• activated partial thromboplastin time

Question 9

which tests measure the instrinsic pathway and which ones measure the extrinsic pathway?

Answer 9

ACT and aPTT measure the instrinsic (PITT)
PT measures the extrinsic (PET)

Question 10

the factors involved in the extrinsic, intrinsic, and common pathways

Answer 10

extrinsic: factor VII
instrinsic: VIII, IX, XI, XII
common: X, V, II, fibrinogen

Question 11

true or false: ACT is usually prolonged even if changes in coagulation are subtle

Answer 11

FALSE! ACT is usually not prolonged unless coagulation factors are <10% of normal activity, so this test is not super sensitive!

Question 12

PT as an in vitro eval of

Answer 12

extrinsic and common pathways

Question 13

aPTT is an in vitro eval of

Answer 13

intrinsic and common pathwaya

Question 14

what are 6 things you need to remember to do when doing tests for coagulation?

Answer 14

• do an atraumatic venipuncture
• use blood tubes w citrate/blue top
• fill the entire tube
• mix the tube well
• centrifuge and transfer plasma into a non additive tube for submission
• freeze the plasma if sending it to external lab

Question 15

what are some clinical signs of disorders of coagulation?

Answer 15

• large hematomas, hemarrthrosis, bleeding into cavities, delayed severe bleeding with sx, think drip drip oozy

Question 16

the most common cause of coagulopathy in vet med is

Answer 16

anti vitamin K anticoagulants (mainly rodenticide toxicity or mouldly sweet clover)

Question 17

what are the vitamin K dependent coagulation factors?

Answer 17

II, VII, IX, X

Question 18

normally in the liver, vitamin K….

Answer 18

turns the factors into their active forms

Question 19

how do you treat a coagulopathy casued by a rodnticide toxicity or eating mouldly sweet clover?

Answer 19

give vitamin K

Question 20

which tests (ACT, PT, aPTT) will be elevated in a case of anti vit K anticoagulant toxicity?

Answer 20

ALL

Question 21

explain why hepatic disease can cause coagulopathy

Answer 21

the liver normally makes coagulation factors, so if the hepatocytes are not working, there is decreased production of coagulation factors, chlestasis can also cause decreased vitamin K absroption

Question 22

which tests, ACT, PT, aPTT, will be elevated in a case of hepatic disease causing a coagulation factor defifnecy?

Answer 22

all! since the liver makes factors from all pathways

Question 23

describe the difference between hemophilia A and hemophilia B

Answer 23

hemophilia A: factor 8 deficinecy (more common)
hemophilia B: factor 9 defieinecy