Haemostasis + Anticoagulants

Question 1

what is haemostasis

Answer 1

maintenance of blood in a fluid state when in circulation, clotting blood at the site of injury, removal of the plug when healing is complete

Question 2

what are thrombi

Answer 2

blood clots

Question 3

what is thrombopietin

Answer 3

regulates platelet production - produced in the liver and kidneys

Question 4

from what is a platelet derived?

Answer 4

a megakaryocyte which is derived from the haemopoietic stem cell

Question 5

how many platelets may be formed from one single megakaryocyte

Answer 5

between 1000-5000

Question 6

what is primary haemostasis

Answer 6

the formation of a platelet plug

Question 7

what do glycoproteins do in terms of helping platelets?

Answer 7

they help with platelet aggregation (binding to the membrane surface)

Question 8

what are the three phases of platelet function

Answer 8

adhesion, activation, aggregation

Question 9

what are the 13 plasma protein “coagulation factors”

Answer 9

they are inert pro enzymes which become activated during haemostasis

Question 10

what does factor 1 involve

Answer 10

fibrinogen which helps with clotting

Question 11

what does factor 2 and 2a include

Answer 11

prothrombin and thrombin

Question 12

what does factor 3 involve?

Answer 12

calcium

Question 13

how does factor 4 help with the physiologic cascade

Answer 13

it binds to factor 7

Question 14

what is another name for factor 8?

Answer 14

anti-haemophiliac A factor

Question 15

what’s another name for factor nine?

Answer 15

anti-haemophiliac B factor or Christmas factorw

Question 16

what is the function of factor 13

Answer 16

it is the fibrin stabilising factor

Question 17

what does vWF stand for

Answer 17

von Willebrands Factor

Question 18

how do some anticoagulants work with respect to calcium?

Answer 18

calcium is necessary for blood to clot, so many anticoags take calcium out of the blood i.e EDTA

Question 19

write a note on EDTA

Answer 19

powder anticoag, sodium and potassium salts coat the inside of the blood tube, chelates Ca2+ from the blood, preserves morphology of blood cells for 24-36hrs, may be used in blood counts, may not be used in haemostatic or coagulation studies

Question 20

write a note on tri-sodium citrate

Answer 20

binds calcium, used in tests for blood function, liquid anticoag, two different conc versions of this anticoag is used. For coagulation tests ratio of 9:1 used, whereas for erythrocyte sedimentation rate test (ESR) 4:1. not suitable for cell counting

Question 21

write a note on heparin

Answer 21

natural anticoagulant, given to patients who are on Warfarin. Lithium heparin is used in clinical chem assays to measure liver + cardiac enzymes and cholesterol hormones and may be used for cytogenetic tests. inhibits normal coagulation by inactivating factor Xa and iia. not suitable for blood counts and coagulation factor studies.

Question 22

What components are the involved in haemostatic mechanism

Answer 22

Blood vessels, Platelets, Plasma coagulation factors

Question 23

What other components ensure that excessive thrombi are not formed?

Answer 23

Natural anticoagulants and Fibrinolytic system

Question 24

Where are platelets formed?

Answer 24

In the bone marrow by fragmentation of the cytoplasm of megakaryocytes

Question 25

What happens in Thrombopoieisis

Answer 25

The precursor of Megakaryocyte, the Megakaryoblast arises from differentiation from the haemopoietic stem cell and colony forming unit CFU-GEMM

Question 26

What is the time interval from differentiation of human stem cell to production of platelets

Answer 26

10 days

Question 27

Where are procoagulant and anticoagulant factors stored?

Answer 27

within platelet granules and are released into the microenvironment

Question 28

What is thromboxane A2?

Answer 28

A powerful vasoconstrictor that platelets contain.

Question 29

What is platelet adhesion?

Answer 29

Where platelets adhere to collagen fibres at the site of injury

Question 30

What is platelet activation

Answer 30

The change in platelet shape activates the platelet and causes the release of procoagulant molecules which provide a surface for the reactions of the coagulation factors.

Question 31

What is platelet aggregation?

Answer 31

The primary reversible aggregation and secondary irreversible aggregation that lead to the formation of the primary haemostatic platelet plug.

Question 32

How does aspirin work?

Answer 32

Reduces the level of platelet aggregation.

Question 33

What is the purpose of an anticoagulant?

Answer 33

To prevent blood from clotting - inhibits the naction of coagulation system factors

Question 34

What ion is essential for blood to clot?

Answer 34

Calcium