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Chapter 25
Blood Cells and the
Hematopoietic System
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Elements of the Hematopoietic System
• All the blood cells and their precursors
• The bone marrow, where blood cells have their origin
• The lymphoid tissues where some blood cells circulate as
they develop and mature
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Composition of Blood
• Fluid/dissolved
components
– Water
• Cellular elements
– Red blood cells
– Thrombocytes or
platelets
– Proteins
– Small molecular
substances
– White blood cells
• Lymphocytes
• Leukocytes
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
• All of the following are cellular components of blood
except which one?
– A. Macrophages
– B. Mast cells
– C. Neutrophils
– D. Eosinophils
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Answer
• B. Mast cells
• Mast cells are not blood cells; rather they are found in
connective tissue and initiate the inflammatory
response.
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Function of the Plasma Components of
Blood
• Carry the cells that transport gases
• Aid in body defenses
• Prevent blood loss
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Plasma Proteins
• Albumin
– Comprises approximately 54% of the plasma proteins
– Contributes to plasma osmotic pressure and the
maintenance of blood volume
– Serves as a carrier for certain substances
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Plasma Proteins (cont.)
• Globulins
– Comprise approximately 38% of plasma proteins
Alpha globulins transport bilirubin and steroids
– Beta globulins transport iron and copper.
– Gamma globulins constitute the antibodies of the
immune system.
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Plasma Proteins (cont.)
• Fibrinogen
– Makes up approximately 7% of the plasma proteins
– Is converted to fibrin in the clotting process
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Neutrophils
• Constitute 50% to 60 % of white blood cells
• Primarily responsible for maintaining normal host
defenses against invading substances
– First cells to arrive at the site of infection
– Have their origins in the myeloblasts found in the
bone marrow
– Move to the tissue for approximately 1 to 3 days
• Die in the tissue discharging phagocytic function or
die of senescence
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Eosinophils
• 1% to 3% of the total number of white blood cells
• Increase in number during allergic reactions and parasitic
infections
– The agents associated with allergic reactions
– In parasitic infections, the eosinophils use surface
markers to attach themselves to the parasite and
then release hydrolytic enzymes.
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Basophils
• 0.3% to 0.5% of the total leukocytes
• Consist of heparin, an anticoagulant, histamine, a
vasodilator, and other mediators of inflammation
• Similar to mast cells
• Involved in allergic and hypersensitivity reactions
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Lymphocytes
• 20% to 30% of the total blood leukocytes
• Function in the lymph nodes or spleen to defend against
microorganisms through the immune response
• Three types
– B lymphocytes
– T lymphocytes
– Natural killer cells
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Monocytes and Macrophages
• 3% to 8% of the total leukocyte count
• Cells survive for months to years in the tissues.
• Important role in chronic inflammation
• Involved in the immune response
– Activating lymphocytes
– Presenting antigen to T cells
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Thrombocytes
• Circulating cell fragments of the large megakaryocytes
• Function to form the platelet plug to helps control
bleeding
• 8 to 9 days in circulation
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Hematopoiesis
• Blood cells originate from pluripotent stem cells in the
bone marrow.
• The proliferation, differentiation, and functional abilities
of the various blood cells are controlled by cytokines.
– Cytokines are hormone-like growth factors.
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Useful Hematopoietic Growth Factors
• EPO
• TPO
• G-CSF
• GM-CSF
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Conditions Responding to Use of
Hematopoietic Growth Factors
• Bone marrow failure
caused by chemotherapy
or aplastic anemia
• Anemia of kidney failure
• Hematopoietic neoplasms
• Infectious diseases such
as acquired
immunodeficiency
syndrome (AIDS)
• Congenital and
myeloproliferative
disorders
• Some solid tumors
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Hematopoietic Growth Factors
• Increase peripheral stem cells for transplantation
• Accelerate cell proliferation after bone marrow
engraftment
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Question
• Is the following statement true or false?
• Hematopoietic growth factors are only associated with
normal production of cells.
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
• False
• In disease states such as polycythemia vera, leukemia,
and other blood cancers, inappropriate production of
growth factors does occur.
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Complete Blood Count
• A complete blood count provides information regarding
the number of blood cells and their structural and
functional characteristics.
• The white cell differential count is the determination of
the relative proportions (percentages) of individual white
cell types.
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Diagnostic Tests
• A complete blood count (CBC) is a commonly performed
screening test that determines the number of red blood
cells, white blood cells, and platelets per unit of blood.
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Obtaining Blood Specimens
• Skin puncture (capillary blood)
• Venipuncture
• Arterial puncture
• Bone marrow aspiration
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Diagnostic Tests
• Blood count
• Erythrocyte sedimentation rate
• Bone marrow aspiration and biopsy
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