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23 Cards in this Set
- Front
- Back
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Hematopoietic organs
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- embryonic and fetal period: yolk sac mesoderm gives rise to blood cells, liver and spleen function in blood cell production
- by ~ 2 mo. gestation, bone begins ossification and marrow cavities form - by ~ 7 mo. gestation, marrow becomes primary blood forming organ |
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bone marrow
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- structure: venous sinuses [sinusoidal capillaries] surrounded by CT stroma consisting of reticular fibers and cells, collagen, fibronectin, laminen, other proteoglycans
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red bone marrow
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active in blood cell production, in adult it is mainly located in flat bones and the ends of long bones
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yellow bone marrow
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mainly adipose, gradually replaces red bone marrow in most bones, inactive bone marrow, some hematopoiesis goes on here
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blood supply to marrow
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- blood cells cross venous sinuses into the circulation by passing through the sinusoidal wall
- nutrient A. to central longitudinal A. which can split into 2 ways, 1. cortical capillaries and 2. medullary capillaries to the medullary veonus sinus to the central longitudinal vein |
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bone marrow stem cells
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- differentiate into blood cells, also have the potential differentiate into other cells types
- pluripotent means that they can go to different cell lines |
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differentiation in bone marrow
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pluripotent stem cells differentiate into 2 main cells type
1. lymphoid stem cell which goes to myeloblasts and lymphoblasts 2. myeloid stem cell which goes to progenitor cells |
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Colony forming cells (CFCs)
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= colony forming units (CFUs), further differentiation from the lymphoid and myeloid stem cells
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lymphoid stem cell
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can go to B and T lymphocytes CFC
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myeloid stem cell
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erythrocyte CFC
- granulocyte/monocyte CFC goes to monocytes and neutrophils - eosinophil CFC goes to eosinophil - basophil CFC goes to basophil - megakaryocyte CFC goes to megakaryocyte to platelets |
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growth factors, colony-stimulating factors, hormones (hematopoietins)
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- individual factors have overlapping fcns but their basic actions are:
-- stimulate proliferation of progenitor or precursor cells -- support differentiation -- enhance mature cell fcn |
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erythropoiesis (RBC production)
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basic maturation
1. synthesis of Hb 2. as Hb syn tapers off, there is a decrease in polyribosomes 3. nucleus condenses and eventually is extruded, it is gotten rid of in the marrow 4. the reticulocyte (immature RBC) is what enters the blood, it does not have a nucleus but has polyribosome so it is capable of Hb syn [increase the # reticulocytes usually means a problem) - CFC to proerythroblast to basophilic erythroblast to polychromatic erythroblast to orthchromatic erythroblast (nucleus extruded) to reticulocyte [lifespan of 3 days] to enters blood strem to loses remaining organelles to mature RBC (~ 120 days lifespan) |
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factors which influence RBC production
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- erythropoietin: stims production of globin
- Vit B12 and IF - folic acid - iron |
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formation of WBCs = granulopoiesis
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basic maturation: azurophilic (lysosomal) granules are produced first followed by production of specific grnaules
-granulocyte/monocyte CFC TO promyelocyte TO neutrophilic myelocyte TO neutrophil -granulocyte/monocyte CFC TO monoblast TO monocyte - basophilic CFC TO promyelocyte TO basophil - eosinophil CFC TO promyelocyte TO eosinophil |
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neutrophils
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as they mature they pass through different compartments, storage
1. bone marrow - medullary formation compartment: mitosis and maturation - medullary storage compartment: release neutrophils on demand, they complete maturation here 2. blood - circulating 6-7 hours - marginating compartment: cells sequester in blood of capillaries 3. CT compartment - ~4 days |
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neutrophilia
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an increas in circulating neutrophils, can be caused by:
- Epi: transient, due to dilation of capillaries and release of neutrophils from margination compartment - glucocorticoids: increase in mitosis - infection: increase # of immature neutrophils released from bone marrow, clinically referred to as "shift to the left" - band cells = immature neutrophils, which have a curved rod-shaped nucleus, have not quite finished their segmentation of the nucleus |
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monocytes
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monoblast TO promonocyte TO monocyte TO circulating monocytes [~8 hrs] TO tissue [where it can become: macrophages, microglia, Kuppfer cells, osteoclasts, Langerhans cells]
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lymphocytes
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- CFCs are formed in the bone marrow but differentiation and maturation occurs in the lymphoid tissue
- T lymphocytes: mature in the thymus - B lymphocytes: undergo maturation in the bone marrow as well as the lymphoid tissues (mainly GALT), endstage is plasma cell, this maturation is completeled in the peripheral tissues - |
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megakaryocytes
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- large multi-nucleated cell in the bone marrow
- invaginations of megakarocyte plasma membrane ramify to form demarcation membranes (canaliculi) around areas of cytoplasm. Cellular process of the it extend into the marrow sinuses and the demarcated areas are pinched off and shed into the blood stream |
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metastatic cancers
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- bone marrow is the common site for blood-brn metastises of malignant tumors
- carcinomas of the breast, prostate, lung, kindey and thyroid are most common - prostatic cancer stim growth of new woven bone with osteosclerotic deposits |
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lymphocytic leukemia
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- malignant clones of leukocyte precursors occur in bone marrow or lymphoid tissue. Depending on the stimulating factors, over-proliferation of specific clones can result in excessive numbers of one type of leukocyte and/or deficiency of other types
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chronic leukemia
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- neoplastic proliferation of more mature leukocyte precursors
- allows for normal production of other WBCs, RBCs, and platelets |
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acute leukemia
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- proliferation of immature "blast" cells, more malignant since these precursors are early stem cells for other cell types
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