haemopoiesis

Question 1

Where does haemopoeisis begin ?

Answer 1

embryonic yolk sac (primitive haemopoisis)

Aortic Gonado Mesonephros (definitive haemopoesis)

Question 2

why is the Vitelline artery the specific site for formation of blood cells

Answer 2

it has the highest sensitivity for hypoxia & can sense the need for new RBCs

Question 3

when does haemopoiesis begin ?

Answer 3

3rd & 4th week of embryonic life

Question 4

Haemopoeitic sites and their timelines

Answer 4

1) Yolk sac (3rd week - 6th week)
2) liver & spleen (6/8thweek to 6/7th month of fetal life)
3) bone marrow (6/7th month to 14 months EUL)

Question 5

What is Extramedullary haemopoiesis?

Answer 5

Abnormal production of blood by the liver in adult life, usually occurs in disease states

Question 6

What is a stem cell ?

Answer 6

any cell that has the ability to differentiate and self renew. moves to sites based on demand

Question 7

What is the cluster of differentiation in a normal stem cell?

Answer 7

CD34+, CD38- , CD33- , THY1+, C-kit+

Question 8

What are hemangioblasts ?

Answer 8

multipotent cells that give rise to haemopoetic & endothelial cells

Question 9

What is homing ?

Answer 9

this is the movement of stem cells from the peripheral blood to the bone marrow.
it is regulated by transcription factors.

Question 10

Growth Factor responsible for homing ?

Answer 10

Stromal-Derived Factor 1 (SDF-1)

*binds to CXCR4 receptors on the surface of stem cells

Question 11

what is mobilization?

Answer 11

movement of stem cells from the bone marrow to the peripheral blood

Question 12

growth factors responsible for mobilization ?

Answer 12

1) granulocyte monocyte colony stimulations factor (GMCSF)
2) granulocyte colony stimulating factor (GCSF)

Question 13

What is HIME?

Answer 13

Haemopoietic Inductive Microenvironment - an envt that is conducive & allows adaptability, survival & proliferation of stem cells

Question 14

What do cells are contained in the stroma ?

Answer 14

1) adipocytes
2) fibroblasts
3) mesenchymal stem cells
4) endothelial cells
5) macrophages
6) collagen
7)osteoblasts

Question 15

what are the growth factors secreted by the stroma ?

Answer 15

Interleukin 5, 13, 3
eotaxin

Question 16

what are growth factors ?

Answer 16

these are glycoprotein hormones that regulate the proliferation and differentiation of haemopoietic progenitor cells
*may act locally (SCF) or circulate in plasma (GCSF)

Question 17

characteristics of growth factors

Answer 17

1) glycoproteins
2) synergic in action
3) act on specific receptors
4) work in hierarchy
5) anti-apoptotic
6) pro-proliferative
7) some are positive in action while some are negative in action

Question 18

how many percent of erythropoietin is synthesized in the kidney ?

Answer 18

90%
*thrombopoietin is made largely in the liver

Question 19

how many percent of erythropoietin is synthesized in the kidney ?

Answer 19

90%
*thrombopoietin is made largely in the liver

Question 20

_ are a major source of growth factors

Answer 20

Stromal cells

Question 21

Growth factors with positive action include (promote proliferation)

Answer 21

1) IL-3
2) transforming growth factor alpha

Question 22

growth factors with negative action

Answer 22

1) transforming growth factor beta
2) interferon gamma
*used as a treatment for hepatitis
*contraindicated in pregnant women(can lead to bone marrow suppression)

Question 23

where is interleukin 3’s activity?

Answer 23

on the lymphoid/myeloid & megakaryocyte/erythrocyte progenitors

Question 24

__ & __ enhance neutrophil, macrophage/monocyte production?

Answer 24

granulocyte monocyte colony stimulating factor (GMCSF) & granulocyte colony stimulating factor (GCSF)

Question 25

__ & _ family of transcription factors commit cells to the myeloid lineage

Answer 25

PU1 & CEBP(CCAAT Enhancer Binding Proteins) family

Question 26

__ & _ family of transcription factors commit cells to the myeloid lineage

Answer 26

PU1 & CEBP(CCAAT Enhancer Binding Proteins) family

Question 27

What transcription factors play important roles in erythropoietic & megakaryocytic differentiation?

Answer 27

GATA 1, GATA 2 & FOG1

Question 28

What transcription factors play important roles in erythropoietic & megakaryocytic differentiation?

Answer 28

GATA 1, GATA 2 & FOG1

Question 29

Two phases of the cell cycle

Answer 29

1) Mitotic(M) phase - here the cell physically divides 2) interphase (I) phase - here chromosomes are duplicated & cell growth occurs prior to differentiation

Question 30

Two stages of mitotic phase

Answer 30

1) mitosis - nuclear division is accomplished 2) cytokinesis - cell fission occurs

Question 31

The stages of interphase in cell cycle

Answer 31

1) G1 phase - cell begins to commit to replication 2) S phase - DNA content doubles & chromosomes replicate 3) G2 phase - cell organelles are copied & cytoplasmic content is increased.

Question 32

What major classes of molecules control the checkpoints of the cell cycle ?

Answer 32

1) cyclin dependent protein kinases 2) cyclins

Question 33

Define Epigenetics

Answer 33

This refers to changes in DNA & chromatin that affect DNA expression other than those that affect DNA sequence.

Question 34

characteristics of apoptosis

Answer 34

1) cell shrinkage 2) condensation of nuclear chromatin 3) fragmentation of the nucleus 4) cleavage of DNA at internucleosomal sites

Question 35

What protease action results in apoptosis

Answer 35

Caspases