Hematpoiesis Flashcards
What is the usual value for hematocrit?
50%
What is the MOA of stroke and MI using rhEPO?
increased blood viscosity
Rapid clotting
What is the lifespain of lymphocytes, geerally?
years
What is the lifespan of RBCs, generally?
120 days
What is the lifespan of platelets, generally?
7-10 days
What is the lifespan of granulocytes, generally?
6-8 hours
What are the three granulocytes?
Eosiniphils
Basophils
Neutrophils
What is the most numerous type of blood cell in the bone marrow?
granulocytes
What type of cells in the bone marrow give rise to all other cell types?
stem cells
Can you identify stem cells in the bone marrow morphologically?
no
What percent of bone marrow is made up of stem cells?
0.1-0.01%
What are the cells that provide a microenvironment in bone marrow, for the development of other cells?
Stromal cells (adipocytes, fibroblasts, reticuloendothelial cells)
True or false: immature stem cells are only loosely associated with the stromal cells found in the bone marrow
False–very tightly bound
What happens to the amount of binding of stem cells to the stromal cells as they mature in the bone marrow?
Weaker binding
What regulates the binding of cells in the bone marrow?
Different expression of cell adhesion molecules
How do cells in the bone marrow know what to become?
Cytokines inform what they should become
What is the cytokine that tells cells in the bone marrow to differentiate into RBCs?
erythropoietin
What are the cells that release erythropoietin?
Peritubular cells in the kidney
What is the cytokine that is released to stimulate cells to differentiate into neutrophils?
G-CSF
What do cells exposed to G-CSF turn into?
Granulocytes (usually PMNs)
What are the cells that release G-CSF to increase the production of PMNs?
macrophages at inflammatory sites
What inhibits the production of EPO?
Oxygen pressure
What doe TGF-beta do to the production of stem cells?
Downregulate
What is the trigger to produce EPO?
Hypoxia in the peritubular interstitial cells of the kidney
How does TGF-beta decrease the production of cells?
Downregulate the differentiation cytokines
What is the chemical that is used to increase the production of bone marrow, and also release the bone marrow cells into the blood?
G-CSF
What is the chemical given to chemo pts undergoing radiotherapy, to increase the production of bone marrow?
G-CSF
What is the function of GM-CSF?
increases myeloid cell receovery in bone marrow transplantation pts
Why isn’t MG -CSF used more often to retrieve bone marrow cells?
Causes thrombosis and leay capillary syndrome
Which is typically active: yellow or red bone marrow?
Red marrow
What is yellow bone marrow?
inactive bone marrow in adipose tissue
True or false: in the first few years of life, most of the bone marrow is yellow
False–most is red
What is extramedullary hematpoiesis?
hematpoiesis that takes place outside the bone marrow (liver and spleen)
What happens to the cell size as they mature?
decrease
What happens to the nuclear:cytoplamic ratio as cells mature in the bone marrow?
Decrease
What happens to the nucleoi number as a cell matures
Decrease
What happens to cytoplasmic staining as a cell matures? What does this indicate?
Darker blue to lighter blue, which indicates less RNA
What are retriculocytes?
Immature RBCs
When/where in development does erythropoiesis begin to take place? Where next?
embryonic yolk sac
Extramedullary organs
What is the normal amount of reticulocytes in the blood?
1%
What are band cells?
Immature granulocytes
What is the normal percentage of band cells?
3-5%
What do band cell look like histologically?
horseshoe shaped nucleus
Left shift = ?
More bands
Where are granulocytes removed from the blood? What are the cells that remove them?
Phagocytes in the spleen
Where are PMNs found in the blood?
Half circulating
Half attached to cell walls
What are monocytes?
Baby macrophages
What are histocytes?
macrophages in loose CT
What are kupffer cells?
Macrophages in the liver
What are osteoclasts?
Macrophage in bone that resorb bone
What are microglial cells?
macrophages in the CNS
What is lymphopoiesis?
production of lymphocytes (T cells/B cells, NK cells)
Are NK cells part of adaptive/acquired immunity?
no–innate
Where are B cells produced from?
Bone marrow
B cells initially only express what antibody on their cell surface?
IgM
What happens to immature B cells that only have IgM, that encounter antigen
Undergo apoptosis
What are the two outcomes of a B cell encoutering an antigen?
Become plasma cell
Become memory cell
Where are T cells produed from? Where do they mature?
Bone marrow
Thymus
Once T cells reach the thymus, what are they then called?
thymocytes
Where do mature T cells after exiting the thymus?
lymphatic tissue
What are the cells that produce thrombocytes?
Megakaryocytes
What is the process the megakaryocytes undergo
Endomitosis (nuclear mitosis without cytoplasmic divisions)
What cytokine stimulates thrombopoiesis and endomitosis?
Thrombopoietin
What happens to old platelets?
Spleen/liver phagocytes eat ‘em up
True or false: we have an emergency reserve of platelets in the spleen
True
What does the absolute cell count provide?
Quantity of each cell type per unit volume
What does the differential count provide?
Relative count (% of each cell type)
Elevated eosinophils = ?
Allergies or parasitic infection
About what percent of WBCs are PMNs, (normally)?
50%
What is the normal reticulocyte count (% of RBCs)?
0.5-1.5% of RBCs
