Term
| 3 stages of prenatal hematopoiesis: |
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Definition
1. first stage - occurs during the first month of gestation
-blood cells in the yolk sac originate in angiogenic cell clusters ("blood islands")
2. second stage - occurs in the second month of gestation
-mesodermal cells invade the liver
-liver is the major center of hematopoiesis in the fetus
-meamtopoiesis occurs in the liver and spleen
3. third stage - most prominent during late pregnancy
-hematopoiesis occurs in the bone marrow of bones as they become ossified |
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Term
| Where does normal post-natal hematopoiesis occur? |
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Definition
In bone marrow
In pathological conditions - hematopoiesis can occur elsewhere. |
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Term
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Definition
-self-renewal
-low mitotic activity
-daughter cells can either remain pluripotent or irreversibly differentiate to become progenitor cells
-form both lymphoid and myeloid cell lines |
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Term
| The general flow from stem cells to the end result: |
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Definition
| pluripotent cells (stem cells) - progenitor cells - precursor cells (blasts) - mature cells |
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Term
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Definition
-formed from pluripotent daughter cells
-can divide mitotically to form more progenitor cells or continue differentiation to form precursor cells |
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Term
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Definition
-from progenitor cells
-DO NOT SELF-RENEW
-can only divide to form mature cells |
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Term
| trend for the size of the cell and nucleus: |
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Definition
| As cells further differentiate, the size of the cell and nucleus decreases |
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Term
| trend for the potential to form different kinds of cells (potentiality) |
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Definition
| As further differentiation occurs, the potentiality decreases |
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Term
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Definition
| As further differentiation occurs, the ability to self-renew decreases (precursor and mature cells are unable to self-renew) |
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Term
| trend for the number of distinguishable morphological characteristics |
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Definition
| As further differentiation occurs, more morphological characteristics are identifiable |
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Term
| trend for differentiated functional activity |
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Definition
| As further differentiation occurs, cells are more able to differentiate their functional activity |
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Term
| At which stages of differentiation are growth factors present? |
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Definition
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Term
| What types of cells make growth factors involved in differentiation? (4) |
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Definition
1. macrophages
2. fibroblasts in bone marrow
3. endothelial cells in sinusoids
4. T-lymphocytes |
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Term
| Functions of growth factors: (3) |
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Definition
1. sitmulate proliferation of progenitor and precursor cells
2. support the differentiation of maturing cells
3. enhance the function of mature cells |
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Term
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Definition
-produced by the cortex of the kidney (renal interstitial cells)
-stimulates the formation of RBCs
-athletes will try to use EPO to give them the edge |
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Term
| Where is bone marrow found? |
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Definition
-shafts of long bones
-cancellous bones |
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Term
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Definition
-mostly adipose tissue (gives it the yellow color)
-does not produce RBCs
-converted from red bone marrow with aging |
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Term
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Definition
-contains blood and blood-forming cells
-consists of:
-stroma of hematopoietic cords of cells (fibroblasts that secrete collagen I and III), sinusoidal capillaries, loose reticulum of fibers for support |
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Term
| Functions of red bone marrow: (3) |
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Definition
1. hematopoiesis
2. destruction of aged RBCs
3. storage of iron in macrophages - recycled from the destruction of old RBCs |
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Term
| What causes the release of RBCs from bone marrow? (3) |
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Definition
1. bacterial toxins
2. C3 component of complement (a bacterial protein in the immune system)
3. glucocorticoid homone (from the adrenal ctx) and androgens |
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Term
What four factors are necessary for the maturation of RBCs?
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Definition
1. folic acid
2. vitamin B12
3. EPO
4. iron |
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Term
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Definition
| erythroblast stem cell - proerythroblast - basophilic erythroblast - polychromatophilic erythroblast - normoblast - reticulocyte - mature RBC |
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Term
| nuclear diameter and cell volume trend in RBC maturation |
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Definition
| Nuclear diameter and cell volume decrease in RBC maturation |
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Term
| trend in chromatin condensation in RBC maturation |
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Definition
| As RBCs mature, chromatin condenses until it becomes a pyknotic nucleus which is ejected from the normoblast stage of RBC maturation to form a reticulocyte |
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Term
| Amount of polyribosomes trend in RBC maturation |
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Definition
the amount of polyribosomes decreases during maturation as the amount of Hb increases
-mature RBCs have all the Hb they will ever have |
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Term
| Trend in the amount of Hb in cells during RBC maturation |
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Definition
| The amount of Hb in cells increases during RBC maturation. Since Hb stains eosinophilic, maturing RBCs become more eosinophilic-ly stained |
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Term
| characteristics of proerythroblast: |
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Definition
-large diameter, large nucleus
-lightly-stained chromatin (not very dense)
-prominent nucleoli
-light blue cytoplasm |
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Term
| characteristics of basophilic erythroblast: |
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Definition
-large diameter, large nucleus
-no nucleoli
-thin rim of dark blue cytoplasm (lots of polyribosomes) |
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Term
| Characteristics of polychromatophilic erythroblast: |
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Definition
-smaller diamter
-round nucleus containing chromatin with a mottled appearance
-blue/gray/pink cytoplasm due to different concentrations of Hb throughout |
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Term
| Characteristics of normoblast (orthochromatophilic erythroblast): |
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Definition
-small diameter
-pyknotic nucleus (ready for extrusion from the cell)
-eosinophilic cytoplasm (due to increased Hb content and less polyribosomes)
-normoblasts do not divide mitotically, unlike previous stages of development |
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Term
| characteristics of reticulocytes: |
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Definition
-newly formed RBCs released out into circulation
-still contain some rRNA |
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Term
| Stages of granulocyte development: |
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Definition
| myeloblast - promyeloblast - metamyeloblast - band/stab cell - mature granulocyte |
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