Red Cells 1 Flashcards
What is erythropoietin?
A hormone that stimulates red blood cells in the bone marrow
Where is erythropoietin made?
Kidneys and liver
How long to RBCs live for?
120 days
How does erythropoietin cause red blood cell maturation?
Proerythroblasts (immature RBCs) have erythropoietin receptors.
Erythropoietin binds to the receptors and cause them to mature into red blood cells.
They prevent immature RBCs from killing themselves via apoptosis.
What stimulates erythropoietin production?
When the demand of oxygen in the kidneys isn’t being met the kidneys produce more.
Which condition can cause low erythropoietin?
Chronic kidney disease - that’s why CKD can cause low RBCs and naemia.
Where is haemoglobin created?
By stem cells.
What is anaemia?
A reduction in red blood cells or in their haemoglobin content.
Its NOT a diagnosis.
What are common causes of anaemia?
Blood loss
Increased destruction of FBCs
Lack of RBC production
Defective RBC production
Theres often high levels of haemolytic in the background.
What do you need when creating erythrocytes (RBCs)?
Iron copper Folic acid B12 Erythropoietin
Where does RBC destruction happen?
The reticuloendothelial system
Do RBCs have a nucleus?
They have a nucleus in the bone marrow during production but LOSE their nucleus when they leave the bone marrow.
What are erythrocytes broken down into?
Globin - made into amino acids that are reutilised
Haem - Iron which is reutilised + bilirubin which is converted to bile in the gall bladder
What are the forms of bilirubin?
Unconjugated before it reaches the liver
What do high levels of unconjugated bilirubin mean?
Increased red cell breakdown
When do you get conjugated bilirubin?
After it has been in the liver
What is an immature RBC called?
Reticulocyte
where is a common site of erythrocyte destruction?
SPleen
What are the steps of erythrocyte maturation?
Erythroblast - reticulocyte - erythrocyte
What does a high reticulocyte count in the blood show?
The blood is losing RBCs or it needs more
So the bone marrow is throwing out incomplete RBCs
How long do RBCs look like reticulocytes for after being released into the blood?
24hrs
What is the normal reticulocyte value in the blood?
1%
If you have 10% reticulocytes, this means that 10% of your blood has been lost and needs replaced
What chains make up haemoglobin?
2 beta chains
2 alpha chains
There is a haem molecule associated with each chain.
When is haemoglobin relaxed?
Its relaxed when it carries oxygen and has a tight binding structure when it has to give off oxygen
When is more oxygen bound to haemoglobin?
Increase in pH
Decrease in temperature
Decrease in DPG
(Because less oxygen needs to be given off)
When is less oxygen bound to haemoglobin?
Decrease in pH
Increase in temperature
Increase in CO2
Increase in DPG
(more oxygen needs to be given to tissues)
How are the 2 alpha chains made?
From 4 alpha genes - 2 from mum and 2 from dad
How are the 2 beta chains made?
From 2 beta genes - 1 from mum and 1 from dad
What is the normal make up of haemoglobin?
97% HbA (2 alpha + 2 beta)
2% HbA2 (2 alpha + 2 delta)
1% HbF (2 alpha + 2 gamma)
HbF = foetal haemoglobin
When is HbF replaced with HbA?
At 6 weeks
