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Flashcards in Hematology Deck (373)
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0

What are the sites of fetal hematopoiesis?

0-2 mos: yolk sac
2-7 mos: liver and spleen
5-9 mos: bone marrow

1

How do sites of hematopoiesis differ between infants and adults?

Infants: marrow in all bones
Adult: more limited: *vertebrae and pelvis*, ribs, sternum, skull, sacrum, proximal ends of femur

2

In bone marrow, how many cells are stem cells?

1 in 20x10^6 (20 million)
Beyond this: sign of potential leukemia

3

What are molecular markers for hematopoietic stem cells (HSCs)?

HSC: CD34+ and CD38-

Once committed to differentiation, become CD38+, but lack lineage specific markers.

4

What transcription factors regulate the survival of HSCs in bone marrow?

NOTCH-1
GATA-2

5

What transcription factors commit cells to the myeloid lineage in early hematopoiesis?

PU.1
CEPB family

6

What transcription factors commit cells to erythropoietic and megakaryopoietic lineages?

GATA-1
FOG-1

7

Where are Erythropoietin and Thrombopoietin produced?

EPO: 90% in kidney
Thrombopoietin: Liver

8

3 roles of growth factors in hematopoiesis

1. control of cell cycle
2. gene activation
3. inhibition of apoptosis

9

What is BCL-2?

Anti-apoptotic protein
Production stimulated by growth factor
Inhibits release of cytochrome C from mitochondria

10

3 families of adhesion molecules

Immunoglobin superfamily: antigen dependent surface receptors (TCR, etc) and antigen independent surface adhesion molecules
Selectins: leukocyte and platelet adhesion to endothelium
Integrins: cell adhesion to ECM

11

What is CFU-GEMM?

first step of erythropoiesis: commitment of pluripotent stem cells to non-lymphoid lineage
CFU-GEMM: Colony Forming Unit - Granulocyte, Erythrocyte, Megakaryocyte, Macrophage

12

What is BFU-E?

Erythrocyte Burst Forming Unit - first committed erythroid progenitor
divides -> CFU-E

13

Is there RNA in the cytoplasm of an RBC?

No

14

What is erythropoietin? Where is it produced?

Glycosylated polypeptide (165 AA)
90% produced by peritubular interstitial cells of kidney
10% in liver and elsewhere

15

What factors in the kidney stimulate erythropoietin production?

HIF-2a and B
hypoxia induced

16

What type of anemia results following kidney damage (failure, removal, etc.)

Normochromic, normocytic
Because of reduced production rather than Hb or structure problem.

17

What is normal adult hemoglobin and what are its subunits?

HbA
consists of 2a and 2B

18

What forms of Hb are normally found in adult blood?

HbA (a2B2): dominant
HbF (a2Y2): fetal
HbA2 (a2d2):

19

Where are the components of hemoglobin synthesized?

All in RBC precursor cells
protoporphyrin: in mitochondria
Fe2+: transported by Transferrin -> mito -> + protoporphyrin -> haem
Globin: ribosomes

20

What is the P50 of hemoglobin under normal conditions? How does it change?

P50: partial pressure of O2 at which Hb is 50% sat.
normal blood: 26.6
increased affinity: falls
decreased affinity (ex. 2,3-DPG): rises

21

4 factors that move Hb O2 dissociation curve to the right

Move to right (low O2 affinity)
high 2,3-DPG
high H+
high CO2
HbS

22

factors that move Hb O2 dissociation curve to the left

Move to left (high affinity)
low 2,3-DPG
low H+
HbF

23

What is methemoglobinemia? Causes?

Circulating Hb w/ Fe3+ rather than 2+ (patients often cyanotic)

Hereditary HbM: AA substitution affecting heme pocket
Hereditary deficiency of methemoglobin reductase
Toxic: drug or toxin induced oxidation of Fe2+ in Hb.

24

How do RBCs produce energy?

ATP and NADH: Embden-Meyerhof pathway (glycolytic)
NADPH: Hexose Monophosphate Shunt (PPP)

25

Important proteins in RBC membrane structure.

Band 3 (Cl- / HCO3- exchanger): binds ankyrin which binds protein 4.2 which together bind alpha spectrin

Glycophorin binds protein 4.1 and actin which bind spectrin

26

What is the relationship between anemia and 2,3-DPG?

2,3-DPG usually rises in setting of anemia -> rightward shift of Hb / O2 dissociation curve: Hb gives O2 to tissues more readily.

27

With what Hb concentration do symptoms of anemia usually become apparent?

9-10 g/dL

28

What are the criteria for microcytic, hypochromic anemia, and what are the causes?

MCV: <27pg
Iron deficiency, thalassemia, anemia of chronic disease (some), lead poisoning, sideroblastic anemia

29

What constitutes normocytic, normochromic anemia and what are the types / causes?

MCV: 80-95 fL
MCH: >27pg
may be hemolytic or non-hemolytic
Acute blood loss, chronic disease, renal disease, mixed deficiencies, bone marrow failure (post-chemo)