Practice Questions

Question 1

Name two anticoagulants used in blood samples.

Answer 1

Oxalate and Heparin

Question 2

Which anticoagulant is best used when measuring blood ions? Why?

Answer 2

Heparin. Because other anticoagulants sequester ions.

Question 3

What is the full name for heparin?

Answer 3

Sodium Heparinate

Question 4

Which preservative is used for blood to arrest glycolysis and GNG?

Answer 4

Fluoride.

Question 5

How does Heparin work as an anti-coagulant?

Answer 5

It inhibits the conversion of fibrinogen to fibrin

Question 6

What are 3 anti-coagulants used besides heparin and by what action are they anti-coagulants?

Answer 6

• Sodium citrate
• EDTA (Ethylenediamine Tetra-Acetic Acid)
• Oxalate

They all sequester calcium which is required in the clotting cascade.

Question 7

If you want to measure fibrinogen, would you use plasma or serum? Why?

Answer 7

Plasma because plasma has been treated with anti-coagulants and so the clotting factors such as fibrinogen are still present and not taken up in the process of clotting. Serum is the liquid part of blood AFTER coagulation and therefore is devoid of clotting factors such as fibrinogen.

Question 8

What are 4 common preservatives for urine?

Answer 8

Thymol, Toluene, Formalin and HCl

Question 9

Why are acids used to preserve urine?

Answer 9

To prevent ions such as calcium and phosphates precipitating out of solution. Also to prevent microbial growth.

Question 10

In analysing samples, why does microbiology take priority over biochemistry departments? (If they’re using the same sample for tests)

Answer 10

Because once biochemistry open the sample to analyse it, it’s contaminated so microbiology use the sample first, then biochemistry.