Red cells Flashcards
What are the precursors to red blood cells known as?
Multipotent haemopoietic stem cells
By what process do blood cells arise?
Haemopoiesis
What are the essential characteristics of haemopoietic stem cells?
Being able to self renew
- Some daughter cells remain as HSCs so the pool of HSCs is not depleted
Differentiate to mature progeny
- Other daughter cells differentiate and form different cells
What is eryhtropoiesis?
The development of red cells
What benefit does red cells being concave give them?
It helps in maneuverability through small blood vessels to deliver oxygen
What is erythropoeitin?
A growth factor required for the formation of red blood cells
Required in eryhtropoeisis
A glycoprotein produced in the kidney in response to hypoxia - juxtabular interstitial cells
Stimulates bone marrow to produce more RBCs
What is haemaglobin A made up of?
4 subunits, 2 alpha chains and 2 beta chains
What are haem groups made up of?
A ferrous ion, Fe2+, held in a ring known as porphyrin
Where is iron absorbed?
The duodenum
How are iron levels managed?
No physiological mechanism
Absorption is tightly controlled, 1-2mg absorbed daily from diet
What is hepcidin?
A hormone that inhibits iron absorption
How does an increased erythropoeitic activity effect hepcidin levels?
Increased erythropoeitic activity -> increased iron requirement -> decreased hepcidin -> increased iron absoprtion
What are vitamin B12 and folate used for?
The synthesis of dTTP which is needed for the synthesis of thymidine
What does a lack of B12 and folate result in?
Inhibition of DNA synthesis as thymidine cannot be produced
Affects all rapidly dividing cells
dUMP cannot convert into dTMP
What foods can vitamin B12 be gained from?
Meat, Liver and kidney, Fish, Oysters & Clams, Eggs, Milk & Cheese, Fortified cereals
