Blood and Hemopoesis
 Blood is a connective tissue
 It is formed from formed elements
 Cells
 Platelets
 It is suspended in extracellular matrix (plasma)
 Blood volume in an average adult is 5-6L
 It functions in a number of ways
 Acid-base balance
 Osmotic balance
 Helps regulate body temperature
 Plasma is composed of the following:
 90% water
 7% protein
 fibrinogen (converts to fibrin during clotting)
 albumin (osmotic pressure)
 globulins (antibodies)
 2% amino acids
 vitamins
 hormones
 1% inorganic salts
 serum – the yellowish fluid remaining after blood has clotted, similar to
plasma but lacks fibrinogen and other clotting factors
 mature RBC’s (erythrocytes) lack:
 mitochondria
 ribosomes
 certain enzymes
 Erythrocytes metabolize glucose for their energy needs
 Hematocrit is (estimated percent volume of RBC’s / unit blood)
 RBC’s are 80-90% of all blood cells
 33% is hemoglobin
 anemia – low concentration of RBC’s
 hypochromic anemia – abnormally low concentration of hemoglobin in
each cell due to iron deficiency
 pernicious anemia is due to a lack of/ or uptake problems with vitamin
B12
 polycythemia – increased concentration of circulating RBC’s
 malaria – form of anemia
 parasitic destruction of RBC’s
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Blood and Hemopoesis
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 alterations in RBC membranes that cause aggregation and
obstruction of small cerebral blood vessels
life span of an RBC is approximately 120 days
as they age, RBC’s swell and are destroyed after they are trapped in the
spleen
peripheral proteins are associated with the internal aspect of the cell
membrane
 spectrin – maintains RBC shape
 actin – maintains RBC shape
 ankyrin – binds actin and spectrin to integral proteins on the
cytoplasmic surface of the plasma membrane
leukocytes or WBC’s there are 2 types
 agranulocytes – either lymphocytes or monocytes ; both lack
granules
 monocytes
 12 to 25 microns in diameter
 filopodia
 microvilli
 phagosomes
 pinocytotic vesicles
 large nuclei, acentric and kidney shaped
 live less than 3 days in the blood, or from months to
years in connective tissue as macrophages
 lymphocytes
 round cells prominent nuclei
 20-35% of all WBC’s
 classified as small, medium, or large
 2 classes
 T lymphocytes – cell mediated immunity
 Most numerous
 Can produce lymphokines (attract
macrophages)
 Can secrete cytotoxic substances
 B lymphocytes – humoral immunity
 Can differentiate into plasma cells and
secrete antibodies
 granulocytes – characterized by the specific granules present
 neutrophils
 10 to 15 microns in diameter
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Blood and Hemopoesis
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 has Barr body (evagination from the nucleus)
 granules contain:
 lysozyme
 collagenase
 and other enzymes
 functions in phagocytosing bacteria
 1st line of defense
 eosinophils
 12 to 16 microns in diameter
 granules stain reddish orange
 contains major basic protein
 acts against parasitic worms
 live for less than 2 weeks in connective tissue
 allergic reactions and helminthic (worm) infections
cause an increase in there numbers (eosinophilia)
 corticosteroids cause a decrease
 have an anti-inflammatory role – inactivation of
histamine during allergic reactions
 basophils
 10 to 15 microns in diameter
 contain dark, large granules when stained
 live very long time 1-1.5 years in mice
 contain heparin and histamine
 has an inflammatory role
 determination is based on the presence or lack of granules
all leukocytes contain:
 azurophilic granules – lysosomal in activity
 hydrolytic enzymes
 impart phagocytic ability
diapedesis is the means by which all leukocytes can cross through
connective tissues and provide immunological defense
Platelets – cell fragments from megakaryocytes in the bone marrow
 Hyalomere – peripheral region
 Granulomere – central region
 Rich in fibrinogen and PDGF (platelet-derived-growthfactor)
 Survive about 10 days
 Function in blood clotting
Hemopoesis
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Blood and Hemopoesis
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 6-8 weeks the liver and spleen as well as lymph vessels function in
hemopoesis
 4th-6th month developing bone marrow becomes site of
hemopoesis – by birth it is the only site where it occurs
 involves mitotic division and differentiation of cells derived from
pluripotent stem cells (CFU-S) ( colony forming units spleen)
 CFU-S are present in bone marrow cords
Erythropoesis
 Proerythroblast
 Normoblast
 Starts to produce hemoglobin
 Reticulocyte
 No nucleus
 No more mitosis
 Mature form of hemoglobin produced
 Number of reticulocytes is dependant on physiological
oxygen demand
 It is a measure of RBC formation
 Erythrocyte
 Formed after ubiquitin destroys the remaining organelles
Granulopoesis
 Myeloblast
 Myelocyte
 Band or stab cell
 Granulocyte
Monopoesis
 Monoblast
 Differentiated mature cells
 Monocyte
 Macrophage
Lymphopoesis
 Lymphoblast
 Prolymphocyte
 Lymphocyte
Platelet formation
 Megakaryoblast
 Megakaryocyte
 Fragmentation along internal membranes called platelet
demarcation channels
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platelet
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