Haematology Flashcards
What does APPT (Activated Partial Prothrombin Time) measure?
Monitors the intrinsic pathway
What does PT (Prothrombin Time) measure?
Function of the extrinsic pathway
Describe the common pathway of the coagulation cascade.
Factor Xa –> (Prothrombin –> Thrombin) –> (Fibrinogen –> Fibrin)
(in the presence of phospholipid and calcium)
Describe the extrinsic pathway of the coagulation cascade.
Factor VIIa –> Xa
Describe intrinsic pathway of coagulation cascade.
Factor XIIa –> XIa –> IXa –> Xa
Activated by exposed collagen
What is coagulation?
The mechanism directly leading to the conversion of the soluble plasma protein fibrinogen to the insoluble rigid polymer fibrin
What are platelets?
small disc-shaped particles, no nucleus or capacity for DNA
Describe the composition of Haemoglobin.
- contains four polypeptide chains: two alpha and two beta
- each chain is combined to a ‘harm’ molecule which contains ferrous ions and protoporphyrin.
- iron combines reversibly with oxygen
What is the key function of erythrocytes?
To carry oxygen and return carbon dioxide from the tissues to the lungs
What triggers the synthesis of erythropoietin?
Hypoxia (HIF - hypoxia inducible factor)
Where is erythropoietin synthesised?
Peritubular endothelial cells of the kidney
What are the advantages for RBCs to be denucleated?
- reduced weight
- transformation into biconcave shape which increases SA
