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NR507 hematologic disorders Questions and Answers
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NR507 hematologic disorders
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NR507 hematologic disordersthe site of blood cell formation hematopoiesis varies with age - answer-fetus - yolk sac
beginning 3rd week gestation; shift to fetal liver & spleen by week 8 and to bone marrow
by 5 month
-birth to 5 years red marrow of all bones make blood cells
-after 20 years red marrow primarily located in ilium, vertebrae, cranium and jaw,
sternum and ribs, humerous and femur.
Hematopoiesis occurs throughout life and is stimulated by - answerinfiltration of the
yellow or fatty bone marrow with red bone marrow cells.
faster proliferation and differentiation of stem and daughter cells.
Hematopoietic stem cells are - answer-are progenitors (apart of) of all hematological
cells.
-proliferate and differentiate under the control of numerous growth factors and cytokinis
to form the three types of cells found in peripheral blood: RBCs, WBCs, and platelets
Erythropoiesis - answerformation of red blood cells:
-The growth factor erythropoietin is made by the kidney and to a very small extent in the
liver in response to tissue hypoxia
-is also stimulated by androgens (testosterones)
-Normal red blood cell level is between 4.2 to 6.2 million cells per cubic millimeter
(approximately 45% of blood volume)
-able to replenish 1% of circulating red blood cell mass every 24 hours, which is
equivalent to 2.5 million red blood cell synthesized per second.
The mature RBC structure - answerbiconcave spherical disk for maximum surface area
for gas exchange
reversible deformability to squeeze through capillaries
lacks a nucleus, ribosome, mitochondria ( Without these structures, red blood cells
cannot divide or do protein synthesis and can only perform anaerobic metabolism,
, lifespan in circulation is approximately 100-120 days (But in that time frame, it will have
traveled thousands of miles to our vascular system)
Red blood cells are essentially a sack of hemoglobin. - answerIt is estimated that there
are approximately 300 million hemoglobin molecules per red blood cell. Hemoglobin
makes up 90% of the dry weight of the cell.
males 16
females 14
Hemoglobin has a unique chemical composition that includes polypeptide chains, heme
molecules, and iron.
iron - answer-The primary dietary sources for iron are meats, especially red meat, dry
beans, and eggs.
-absorbed through the GI track and combines with the plasma protein transferrin (the
transporter for iron)→ transport to the liver for storage as ferritin then when needed is
released from the liver via transferrin →bone marrow →Iron enters the erythroblasts
and is transported directly into the mitochondria.
females 19-50 need 18 mg/day
females ˃ 50 and males ˂ 19 needs 8mg fe/day
Vitamin B12 (Cyanocobalamin) - answerPrimary sources are meat, fish, poultry, and
dairy
is required for DNA, RNA and myelin synthesis (Rna synthesis occurs in its absence,
but abnormally large cells form)
stomach secrete intrinsic factor protein to facilitate absorption of vitamin from the ilium.
Any excess B12 - answeris stored in the liver. Typically, we have a 1000 fold excess
reserve, so it can take years to deplete our stores of this vitamin.
Folic Acid (Folate) - answerprimary dietary sources are liver grains and green vegetable
is required for DNA and RNA synthesis and is also important for neural development in
utero.
absorbed directly from the GI tract in any excess is stored in the liver and depleted in 2
to 3 months
red blood cells (erythrocytes) - answernormal recycling occurs as metabolic processes
decrease.
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