Week 3 Flashcards
(24 cards)
What is the primary function of haemoglobin?
To transport oxygen from the lungs to tissues and return carbon dioxide to the lungs.
What is the difference between HbA and HbF?
HbA (adult) = α2β2, HbF (foetal) = α2γ2, with HbF having a higher oxygen affinity
What is the Bohr effect?
Haemoglobin releases oxygen more readily in response to high CO₂ or low pH.
What factors shift the oxygen dissociation curve to the right (reducing O₂ affinity)?
Increased CO₂, increased 2,3-DPG, increased temperature, and decreased pH.
What factors shift the oxygen dissociation curve to the left (increasing O₂ affinity)?
Decreased CO₂, decreased 2,3-DPG, decreased temperature, and increased pH.
what is carboxyhaemoglobin, and why is it dangerous?
Haemoglobin bound to carbon monoxide (CO), which prevents oxygen binding and delivery.
What is methaemoglobin, and why is it problematic?
Haemoglobin with iron in the Fe³⁺ (ferric) state, which cannot bind oxygen.
What enzyme normally converts methaemoglobin back to functional haemoglobin?
Cytochrome-b5 reductase (methaemoglobin reductase).
What is thalassaemia? two types?
A genetic disorder causing reduced or absent production of globin chains.
Alpha-thalassaemia and beta-thalassaemia.
What is the main cause of beta-thalassaemia major?
Mutations in the HBB gene, leading to absent or reduced beta-globin production.
What mutation causes sickle cell disease?
A single point mutation in the HBB gene
What is the main clinical consequence of thalassaemia major?
Severe anaemia requiring lifelong blood transfusions
Why do thalassaemia patients need iron chelation therapy?
To prevent iron overload from frequent blood transfusions.
What happens to red blood cells in sickle cell disease?
They become rigid and sickle-shaped, causing blockages in blood vessels.
Why is sickle cell disease more common in malaria-endemic regions?
Carriers (HbAS) have resistance to malaria, providing a selective advantage.
What is the main cause of pain crises in sickle cell disease?
Vaso-occlusion caused by sickled red blood cells blocking blood flow
What are major complications of sickle cell disease?
Stroke, organ damage, infections, and chronic pain.
What is the only potential cure for sickle cell disease?
stem cell transplant
What test is commonly used to detect haemoglobin variants?
Haemoglobin electrophoresis.
What genetic test is used to confirm sickle cell disease?
PCR-based mutation analysis of the HBB gene.
What is the main treatment for severe thalassaemia?
Regular blood transfusions and iron chelation therapy.
What is Crizanlizumab, and how does it help in sickle cell disease?
A monoclonal antibody that prevents vaso-occlusion by blocking P-selectin.
What is voxelotor, and how does it help in sickle cell disease?
A drug that stabilizes haemoglobin and reduces sickling.
Where does haem synthesis occur?
Liver + RBC precursors
