Hematopoiesis

Question 1

what is hematopoiesis?

Answer 1

the process in which formed elements of blood (platelets (thrombocytes, erythrocytes and WBCs) are produced

Question 2

when does hematopoiesis being?

Answer 2

Yolk sac phase - 3rd week of gestation = blood islands

Question 3

What is the major blood forming organ in the second trimester? what else begins during the second trimester?

Answer 3

liver (little teeny bit of spleen)= hepatic phase

bone marrow phase

Question 4

after birth, where does hematopoiesis only take place?

Answer 4

in bone marrow

Question 5

What is stem cell niche

Answer 5

a spatial structure (microenvironment) in which HSCs are housed and maintained by allowing self renewal in the absence of differentiation.

Question 6

what is the stem cell niche functions?

Answer 6

storage of quiescent stem cells
self renewal
inhibition of differentiation

Question 7

what is the stroma made of and what does it give rise to?

Answer 7

made of cells derived from mesechymal stem cells 
give rise to fibroblasts
adipocytes
endothlial cells
osteoblasts

Question 8

where are stem cell niche (endosteal niche) found?

Answer 8

epiphyseal areas - spongy bone

Question 9

what is the vascular niche?

Answer 9

where the HSCs migrate towards to teh center of bone marrow to vascular zone where they est. hematopoiesis
this specific site is where endothlial cells, fibroblasts and adipocytes and found

Question 10

what are three important growth factors that contribute to hematopoiesis?

Answer 10

erythropoietin - kidney
thrombopoietin - liver
cytokines
GM-CSF - myeloblast - BEN, monocyte
IL-7 - lymphocyte

Question 11

hematopeitic cells will die unless exposed to hwat?

Answer 11

growth factors

Question 12

what is the main stimulus for erythropoetin?

Answer 12

hypoxia

Question 13

as a cell develops, they _____ in size and their nuclei ______-

Answer 13

decrease

condense