Which is essential for allowing co 2 and h 2 0 to

., which is essential for allowing CO
2
and H
2
0
to react.(buffer system more later)
 Hemoglobin - consists of four protein chains attached to a heme (iron containing)
group. One oxygen atom can bind to each heme group therefore making the
hemoglobin completely saturated.
 Carbon monoxide binds irreversibly to hemoglobin, thus rendering it ineffective
to carry oxygen.
 Fetal hemoglobin is much more effective at binding oxygen than is adult
hemoglobin.
 Iron is necessary for hemoglobin to function, properly and without it anemia
can ensue.
 Main component of RBC
B. Formation of RBC’s
1. General Information
 Hematopoiesis takes place in the red bone marrow.
 Marrow makes about an ounce of blood each day.
 Hemocytoblast – stem cells for blood cell production.
2. Erythropoiesis – formation of RBC’s
 Hemocytoblast  myeloid stem cell  proerythroblast  early erythroblast  late
erythroblast  normoblast  reticulocyte  erythrocyte.
o Hemocytoblast: bone marrow stem cell, can become any blood cell
o Proerythroblast: RBC stem cell, has receptors for EPO
o Erythroblast: begins making hemoglobin
o Reticulocyte: often found in hypoxic situations
 Hemoglobin begins accumulating in the second phase
 Nucleus is ejected form the normoblast.
 RBC’s are produced at a rate of about 2 million/sec!
3. Hormonal Controls
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Nur 0013 Spring 2014
 Erythropoietin (EPO) – hormone released by kidney cells in response to:
 Decreased RBC in circulation
 Decreased O
2
availability
 Increased tissue demands for O2
 EPO stimulates red bone marrow to produce more RBC’s
 Within 1-2 days reticulocyte count increases.
 Hypoxia is a major factor in stimulating this system
C. Death of RBC - Hemolysis
 After 90-120 days membrane becomes fragile and rigid
 Membrane degraded in either spleen or liver
 Hemoglobin disposed by liver.
 Broken into heme and globin components
 Heme broken down into bilirubin in SI, and iron is recycled.
 Globins – are recycled
D. RBC disorders.
Are often related to not enough or too many cells
 Anemias –
 Lack of RBC’s- blood loss, malformation
 Hemorrhagic
 Hemolytic (Ecoli)
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Nur 0013 Spring 2014
 Aplastic(bone marrow destroyed)
 Low Hemoglobin counts
 Iron Deficient
 Pernicious(lack of intrinsic factor and hence vit B12)
 Defective Hemoglobin – Often genetic
 Thalassemias – faulty globin chains
 Sickle cell, single amino acid change during transcription
 Causes the cell to become stiff and elongated due to malformed
hemoglobin
 One of the more common genetic diseases that affects RBC
 Polycythemias
 Polycythemia vera – often caused by marrow cancer.
 Blood doping – secondary cause
IV. Formed Elements - WBC
A. Leukocytes (WBC) ~5000-10,000/µL
 Are truly cells , they are only about 1% of blood by volume.
 Hormones and other stressors can stimulate their production in red bone marrow
(known as leukopoeisis).
 Stimulants for formation can be hormonal or other stressors
 Once produced they move out of the blood vessels in a process known as
diapedesis and eventually to the site of an immune response.
