Red and white blood cells Flashcards
What is haemopoiesis?
Formation of red blood cells from the bone barrow from HSC’s
Where are red blood cells produced and what are they derived from?
Bone Marrow
Haemopoietic Stem Cell → Myeloid Progenitor
Foetal haemopoiesis - embyronic yolk sac then fetal liver - all bone marrow in children
How many blood cells does the human body produce per day?
173 million
What two. features do HSCs have?
Self - renew
differentiate into mature cells
What is the life span of an erthyrocyte, platelet, monocyte, neutrophil, eosinophil and lymphocyte?
erthyrocyte 120 days platelet 10 days monocyte several days neutrophil 7-10 hours eosinophil less than neutrophil lymphocyte variable
What does erythropoiesis require?
Iron
Folate and Vit B12
Erythropoietin - made in kidney raised in hypoxia and anaemia
Where is erythropoietin made and when is it released?
Made in the kidney in response to hypoxia and anaemia
What is the difference between haem and non haem iron?
Haem - ferrous Fe(II)- best absorbed
Non-haem - ferric Fe(111) needs to be reduced before being absorbed (hard to bind oxygen)
What is the role of iron in erythropoiesis?
Role in haemoglobin, makes cytochromes a,b,c and p450
What substance reduces iron absorption?
Phytates - often found in non-haem iron sources
What is hepcidin? What is it suppressed by?
Substance that blocks the absorption and release of storage iron by blocking of ferroportin
Suppressed by erythropoietic activity
What affect does erythropoiesis have on iron absorption?
Increases iron absorption by increasing ferroportin in duodenum enterocytes
How do we lose iron?
High levels of iron cause an increase in hepcidin which inhibits ferroportin, which causes iron to stay in the enterocytes rather than go in the blood and is lost when the enterocytes are shed
What is anaemia of inflammation?
Inflammation causes release of hepcidin which blocks ferroportin and keeps iron in the enterocytes which are eventually shed
Why is vitamin B12 and folic acid vital ?
They make dTTP (deoxythymidine triphosphate) which is involved in thymidine synthesis which leads to DNA synthesis
Where is b12 found?
Meat, liver, kidney, fish, oysters, clams, eggs, milk, cheese, fortified cereals
Where is Folic acid found?
Green leady veg, cauliflower, brussels sprouts, liver, kidney, wholegrain cereal, yeast, fruit
How is absorption of B12 done?
Combined with intrinsic factor made in gastric parietal cells > B12-IF can bind to receptors in the ileum
Once in the circulation, B12 is bound to the transport protein transcobalamin.
What can cause vitamin B12 deficiency?
Inadequate intake
pernicious anaemia - Autoantibodies that interfere with the production or function of IF so there is a inadequate secretion of IF so B12 can’t be absorbed:
Malabsorption ie coeliac disease
Lack of acid in stomach
Why are red blood cells only useful for 120 days and how are they removed?
They travel bent and thus stretch in vessels thus get damaged easily
they bind to haptoglobin and are removed by the phagocytic cells of the spleen
What is released when red blood cells are broken down?
Haem which is broken down into billirubin and is released by the liver as bile - iron is returned to bone marrow
Also Amino acids form
What is hypochromia? what is it often associated with?
Hypochromia means that the cells have a larger area of central pallor than normal
This results from a lower Hb content and concentration, and a flatter cell
Hypochromia and microcytosis often go together
What is polychromasia? What can it lead to?
Too red/dark red blood cells
an increased blue tinge to the cytoplasm of RBCs
It indicates the red cell is young
Polychromatic cells are larger than normal red cells i.e. polychromasia is one of the causes of macrocytosis
What does increase in reticulocytes show?
red cells destruction or bleeding
What is microcytic anaemia?
Iron deficiency often results in hypochromia
What is macrocytic anaemia?
B12 and folate deficiency
often results in polychromasia
What is a target cell and what can cause this ?
Accumulation of Hb in centre of the cells where it is usually pale Obstructive jaundice Liver disease Haemoglobinopathies Hyposplensjm
What is anisocytosis?
Variation in size of red blood cell
What is poikilocytosis?
Variation in shape of of red blood cells
What do macrophages store and release?
Iron
How long do monocytes spend in circulation? What do they do?
Monocytes spend several days in circulation
-present antigens to lymphoid cells
-Monocytes migrate to tissues where they develop into macrophages (also known as histiocytes) and other specialised cells that have a phagocytic and scavenging function
can store and release iron
Where do monocytes migrate to and what do they develop into?
Monocytes migrate to tissues where they develop into macrophages (also known as histiocytes) and other specialised cells that have a phagocytic and scavenging function