Hematopoeisis Flashcards
Where does hematopoeisis take place in the fetus during the first trimester?
There are islands of hematopoeisis in the yolk sac that develop from hemangioblasts
What are hemangioblasts?
Progenitors for both hematopoeitic and endothelial cells
Where does hematopoeisis take place in the fetus during the second trimester?
Liver and spleen
[this is extramedullary hematopoeisis, meaning outside the bone]
Where does hematopoeisis take place in the fetus in the 7th month of pregnancy?
In the bone marrow, which now becomes the primary source of hematopoeisis
Bone marrow remains the primary source of hematopoeisis into adulthood, and dominates in which skeletal areas?
Skull Clavicles Vertebrae Ribs Sternum Pelvis Ends of long bones
When in crisis, adults can reactivate previous sites of active marrow in an attempt to increase hematopoeisis. Which two extramedullary areas are targeted?
Liver and spleen
Bone marrow consists of what 2 compartments?
Hematopoietic cell compartment
Marrow stromal compartment
Which area of the bone marrow is highly vascular?
Hematopoeitic cell compartment
Which area of the bone marrow produces hematopoeitic growth factors (endothelial cells, marrow fibroblasts, and reticulocytes)
Marrow stromal compartment
What is the source of energy for the marrow stromal compartment?
Adipose cells
_________ bone marrow is not active in blood cell formation because it is made up predominantly of adipose cells
Yellow
What is the chief form of bone marrow in the medullary cavities of bones in adults, particularly long bones of the arms, legs, fingers, and toes?
Yellow bone marrow
[although hematopoeitically active bone marrow does contain some fat]
A slide showing no red in the bony trabeculae would indicate _________ anemia, meaning no production of any cells in the bone marrow
Aplastic
Stromal structure consists of:
Stroma, which contains __________ connective tissue, adipocytes, and macrophages.
Hematopoeitic _______, which are bundles of blood cells at different stages of maturation.
Vascular ___________, which lie between the above structures and ar elined with endothelial cells. Often ____________ discharge protoplatelets into this area.
Reticular
Cords
Sinusoids; megakaryocytes
What is the significance of hematopoeitic stem cells?
They are capable of self-renewal; very few cells can do this and there is a potential for malignancy.
________ stimulates the differentiation of multipotent (pluripotent) hematopoeitic stem cells into lymphoid progenitor cells, as well as proliferation of all cells in the lymphoid lineage.
IL-7
Committed precursor cells generate distinct cell lineages under the influence of 5 _________, derived from the myeloid stem cell
CFUs (colony-forming units)
What cell types are derived from the lymphoid progenitor cells?
B cells
T cells
NK cells
What cell types are derived from the myeloid stem cells?
RBCs Platelets Monocytes (macrophages) Neutrophils Eosinophils Basophils
Maturing cells in either cell lineage are considered committed. ________ _________ preserves the pool of stem cells and is critical for feeding common myeloid progenitor and common lymphoid progenitor into the differentiation or maturation pathway.
Self renewal
What is the primary control for proliferative and maturational phases of hematopoiesis, and can also be used as a clinical treatment?
Hematopoietic growth factors
These are produced in bone marrow by endothelial cells, stromal cells, fibroblasts, developing lymphocytes, and macrophages
What are the 3 major groups of hematopoietic growth factors?
Colony-Stimulating Factors (CSF’s)
Erythropoietin (EPO) and Thrombopoietin (TPO)
Cytokines (primarily interleukins)
__________ is the growth factor for neutrophils
G-CSF
__________ is the growth factor for neutrophils, eosinophils, basophils, monocytes, and dendritic cells. It acts synergistically with EPO to support RBC lineage and with TPO to stimulate megakaryocyte progenitors
GM-CSF
__________ is the growth factor for macrophages
M-CSF
__________ is the growth factor for the erythroid lineage
EPO
__________ is the growth factor for megakarycyte progenitors and hematopoietic stem cells
TPO
___________ is also known as c-Kit ligand or Steel factor. It is produced by fetal tissues and bone marrow and acts as a weak stimulator of hematopoiesis. It makes stem cells responsive to other cytokines
SCF (Stem Cell Factor)
_______ ligand is closely related to SCF. It acts on pluripotent stem cells in synergy with TPO, SCF, and interleukins
Flt3
________ is the interleukin that influences replication and growth potential of hematopoietic progenitors
IL-3
Which interleukins act on pluripotent stem cells to develop into lymphoid stem cells?
IL-1
IL-4
Which interleukins are specific to B and T cell growth and development?
IL-2 –> T cells
IL-2 and IL-6 –> B cells
True or false: GM-CSF is less potent than G-CSF for increasing neutrophils during neutropenia
True
EPO is the hematopoietic growth factor primarily produced in the ___________ in response to _________, and stimulates the formation of erythrocytes
Kidney; hypoxia
[thus EPO synthesis is severely impaired in chronic renal disease]