Week 1 Flashcards
Normal morphological maturation of granulocyte precursors
Blast (3-4%)–> promyelocyte (2-8%) –> myelocyte (10-13%) –> metamyelocyte (10-15%)–>bands and neutrophils (25-40%)
Which cells of granulocyte maturation form a mitotic pool in the marrow? Of those which is most common?
blast, promyelocyte, myelocyte (most common)
Which cell of granulocyte maturation has primary granules?
promyelocyte
Which cell of granulocyte maturation has secondary granules?
myelocyte
Which cell of granulocyte maturation has a bean shaped nucleus?
metamyelocyte
Which cell of granulocyte maturation has prominent hof?
myelocyte
What releases G-CSF?
bone marrow and stromal cells
% of bone marrow doing erythropoiesis
20-30%
% of bone marrow doing myelopoiesis
60-70%
What key growth factors can be mimicked by drugs and what do they stimulate?
EPO: BFUe–> CFUe
TPO: BFUemeg–> CFU meg
GM-CSF
G-CSF: CFUgm–> CFUg
Where does G-CSF act?
Blast–> promyelocyte–> myelocyte
What organ releases TPO and is it constiuitive or only when stimulated?
liver; constant
Describe the genetic material of megakaryocytes
polyploid: 16-32n
How are platelets formed?
proplatelets are extended into fenestrated blood vessels in bone marrow and get looped off
What 2 things does TPO bind?
platelets and megakaryocytes
In normal conditions, describe the function of TPO
binds mostly platelets, some goes to megakaryoctes (where it stimulates production of more megakaryocytes and platelet production).
In low platelet, describe the function of TPO?
more TPO binds megakaryocytes stimulating more thrombopoiesis
What is the cell lineage in normal maturation of erythropoiesis?
blast–> pronormoblast–> basophilic erythroblast–> polychomatophilic erythroblast–> normochromic erythroblast
How much of the bone marrow is cellular and active?
100%-age.
Heme synthesis requires:
Iron***, B6, succinyl CoA, glycine (B12+ folate(
globin synthesis requires:
normal globin genes, alpha, beta, amino acids
What usually causes globin problems in the US?
genetic problems rather than malnutrition
DNA synthesis requires:
deoxynucleoside triphosphates (ribonucleotide reductase, thymidine (B12, folate))
For which of the requirements for erythropoiesis is folate and B12 required?
DNA synthesis, Heme synthesis
Morphology of iron deficiency
microcytosis, hypochromia, anisocytosis (size distribution), poikilocytosis ( cell shape variation)
Dietary iron is in _____ state.
Oxidized: Fe3+, ferric
What has to happen for dietary iron to be absorbed?
It has to be reduced in the stomach to ferrous iron (Fe2+) before it can be taken up in the bowel.
What 2 factors affect the ability of dietary ferric iron to be reduced?
low pH, Vitamin C
What happens after iron is absorbed in the bowel?
It is oxidized to Fe3+ (ferric) by serum oxidases then bound to transferrin
Reduced transferrin levels can cause _____.
Low serum iron
What takes up transferrin-bound iron?
bone marrow macrophages via TfR1
How is TIBC calculated?
lab saturates transferrin with added iron.
What does TIBC tell you?
if serum iron is low due to reduced transferrin or not
What is % transferrin saturated?
serum iron concentration/ TIBC
What increases in iron deficiency?
serum transferrin and soluble transferrin receptors
What is reduced in iron deficiency?
serum iron, iron saturation, serum ferritin
Outside of red cells and transferrin, most of the body’s iron stores are bound to a protein called _____.
Ferritin
What morphology is seen with B thalassemia?
microcytosis (may be smaller than in iron def), hypochromia, target cells,
Target cells are not specific; they are commonly associated with ______.
liver disease
How can you tell if a pt has iron deficiency or thalassemia?
Number of red cells. In iron deficiency, the number goes down. In thalassemias, its normal or increased.
How can you confirm a thalassemia after seeing the right lab values?
Because Hb A2 is increased and it migrates differently during electrophoresis. Hb F may also be detected if the thalassemia is severe
Describe the beta globin locus.
It is on chromosome 11. There are 6 copies on each chromosome. 3 are expressed in utero (epsilon, g-gamma, a gamma), psi-beta does nothing, delta is in fetus and low amounts in adults, and finally beta is the form expressed in adults
If expression of beta globin allele is impaired, what may increase?
Hb A2, Hb F if severe
Decribe the alpha globin locus
Chromosome 16; 4 copies on each chromosome. zeta 1 and 2 are expressed in utero, alpha 1 and alpha 2 in adults
What happens when there is a mutation in one of the 4 alpha genes (2 on each chromosome)?
Alpha thalassemia 1 trait
What happens if there are 2 defective alpha alleles?
alpha thalassemia 2 trait
What RBC problems is expected with alpha thalassemia 2 trait
mild microcytic anemia, excess Hgb Barts (gamma 4 tetramer) at birth, normal electrophoresis as adult
how is alpha thalassemia 2 trait diagnosed?
PCR
What percent of population have alpha thalassemia 2 trait
3% of blacks
What happens if there are 3 defective alpha alleles?
Hgb H disease (beta 4)
What are the clinical findings associated with Hgb H disease?
variable degree of microcytic anemia,
What happens if all 4 alpha alleles are defective?
lethal in utero or soon after birth, Hgb H disease
UTP has to be methylated to TTP. Methylation requires what?
B12 and folate
What happens if DNA synthesis is impaired?
fewer cells produced, normal/enhanced maturaion of cytoplasm, impaired nuclear maturation
What are the causes of megaloblastic anemia?
Impaired B12 uptake (pernicious anemia); impaired folate uptake (malabsorption, malnutrition), drug effect (nucleoside analogs [HAART], ribonucleotide reductase inhibitors [hydroxyurea]), intrinsic bone marrow dysfunction (myelodysplastic function)
_____ can impair iron storage usage.
Hepcidin
Chronic inflammation conditions can induce ____ production that impairs utilization of bone marrow iron stores.
Hepcidin
What cytokine is produced in chronic inflamattion that causes production of hepcidin?
IL-6