Blood
Anatomy & Physiology
Functions of blood
Transportation
 Heat regulation
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Composition of blood
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Made of plasma & formed
elements
Plasma: fluid portion of blood
Formed elements
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Red blood cells (erythrocytes)
White blood cells (leukocytes)
Platelets (thrombocytes)
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Watch US blood cells clip
Hematocrit or Packed Cell Volume
(PCV)
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Percent of red blood
cells in whole blood
Buffy coat (less than
1%): white blood cells
& platelets
Erythrocytes (RBCs)
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Mature RBC has no
nucleus, ribosomes,
mitochondria
Small biconcave discs
Primary component:
hemoglobin (1/3 of
cell volume)
Flexible because of
stretchable fibers
called spectrin
Function of RBCs
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Transportation of oxygen & carbon dioxide
depends on hemoglobin & an enzyme
carbonic anhydrase
Hemoglobin
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200-300 million
molecules of hemoglobin
in each RBC
Each hemoglobin
molecule contains 4
protein chains called
globin & each chain is
bound to a red pigment,
heme, which each heme
contains an iron molecule
One hemoglobin
molecule can unite with 4
oxygen molecules
Erythropoiesis
Formation of RBC
 Begins in the bone marrow from
hematopoietic stem cells which form all
blood cells
 In series of steps lose nuclei to become
reticulocyte which is released into
circulation which become mature RBC
which is smaller
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Erythropoietin
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Hormone released by
the kidney when
blood oxygen levels
decline which then
stimulates the bone
marrow to increase
production of RBCs
Destruction of RBCs
Life span of RBC is about 105-120 days
 Macrophages in lining of blood vessels in
spleen & liver phagocytose old or
damaged RBC
 Hemoglobin broken down & amino acids,
iron & pigment bilirubin released
 Iron used to form new hemoglobin &
bilirubin transported to liver & excreted into
the intestines in bile
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Leukocytes (WBCs)
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5 types
All have nuclei
Larger than RBCs
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Granulocytes (have
large granules in
cytoplasm)
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Neutrophils
Eosinophils
Basophils
Agranulocytes
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Lymphocytes
Monocytes
Neutrophils
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About 65% of the total
WBC count
Multilobed nucleus
Small light purple
granules in cytoplasm
Function: cell defense
by phagocytosis of
microorganisms
Life span: hours to 3
days
Eosinophils
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Usually 2 lobed
nucleus
Large orange-red
staining granules
Function: cellular
defense usually
against parasites &
involved in allergic
reactions
Life span: 10-12 days
Basophils
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Usually 2 lobed
nucleus
Sparse, large purple
staining granules
Least numerous WBC
Function: secrete
heparin & histamine
Life span: hours to 3
days
Lymphocytes
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Smallest of WBC, about
25% of total WBC count
Large spherical nuclei
with scant pale blue
cytoplasm
T-lymphocytes: directly
attack infected or
cancerous cell
B-lymphocytes: produce
antibodies against
specific antigens
Life span: days to years
Monocytes
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Largest of the WBC
Kidney bean shaped
nuclei with large
quantities of blue-gray
cytoplasm
Phagocytic cell capable
of ingesting bacteria,
debris, cancerous cells
In tissue called
macrophages
Life span: months
WBC Formation
Neutrophils, eosinophils, basophils
originate in bone marrow
 Most lymphocytes & monocytes originate
in lymphatic tissue
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Watch US platelets clip
Platelets
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Small, nearly
colorless, irregular
3 important physical
properties
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Agglutination
Adhesiveness
Aggregation
Functions of platelets
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Hemostasis: stoppage of blood flow
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Damage to blood vesselsvascular spasm
temporary platelet plug by sticky platelets
secrete ADP, thromboxane & fatty acid
(arachidonic acid) which are involved in
coagulation
Coagulation: blood clotting
Formation & Life Span of Platelets
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Formed in bone
marrow, lungs &
spleen by
fragmentation of very
large cell,
megakaryocyte
Life span: 7 days
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Watch US blood type clip
Blood Types
Refers to the type of antigens, called
agglutinogens, present on RBC membrane
 Important blood antigens: A, B, Rh
 Agglutinins: antibodies dissolved in
plasma that react with specific blood group
antigens
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ABO System
Type A: Antigen A on RBCs
 Type B: Antigen B on RBCs
 Type AB: Antigen A & B on RBCs
 Type O: Neither A nor B on RBCs
 Plasma never contains Ab against Ag
present on it own RBCs
 Plasma does contain AB against those Ag
not present on its RBCs
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The Rh System
Rh positive: Rh antigen is present on
RBCs
 Rh negative: RBCs have no Rh antigen
 Blood does not normally contain anti-Rh
antibodies except thru previous
transfusion or pregnancy
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Blood Plasma
90% water, 10 % solutes
 Most of the solutes are proteins (formed
by liver)
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Albumin: help maintain osmotic balance
 Globulins: immune mechanism
 Fibrinogen: blood clotting
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Remaining solutes are food substances,
metabolic products, respiratory gases,
hormones, etc
Coagulation
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Four components
critical to coagulation
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Prothrombin
Thrombin
Fibrinogen
Fibrin
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Three stages
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Stage I
Stage II
Stage III
Stage I
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Production of thromboplastin activator by
either:
Extrinsic pathway: chemicals released from
damaged tissues
 Intrinsic pathway: chemicals present in the
blood
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Stage II
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Conversion of prothrombin to thrombin by
the prothrombin activator produced in
stage I
Stage III
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Conversion of fibrinogen to fibrin and
production of fibrin clot by thrombin
produced in Stage II
Coagulation facts
Many of clotting factors require calcium ion
as a cofactor
 Liver synthesizes both prothrombin &
fibrinogen. Vitamin K is necessary for
production of prothrombin
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Conditions that oppose clotting
Smooth surface of lining of blood vessels
does not allow platelets to stick
 Antithrombins: substances in blood that
oppose or inactivate thrombin
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Ex: Heparin
Conditions that hasten clotting
Rough spot in the blood vessel lining
 Abnormally slow blood flow
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Clot Dissolution
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Fibrinolysis:
physiologic
mechanism that
dissolves clots
Image Citations
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Slide 5: Hematocrit, 12/20/06,
http://www.drstandley.com/labvalues_hematology.shtml
Slide 13: Neutrophil, 12/27/06,
http://faculty.une.edu/com/abell/histo/histolab3a.htm
Slide 14: Eosinophil, 12/27/06,
http://faculty.une.edu/com/abell/histo/histolab3a.htm
Slide 14: eosinophil1a, 12/27/06,
http://cellbio.utmb.edu/microanatomy/blood/more_eosinophils.htm
Slide 15: Basophils, 12/27/06,
http://faculty.une.edu/com/abell/histo/histolab3a.htm
Slide 16: Medium lymphocyte, 12/27/06,
http://www.anatomy.dal.ca/Human_Histology/Lab7/61LO4.html
Slide 17: Monocyte, 12/27/06, http://www.meded.virginia.edu/courses/path/innes/nh/wcbmaturation.cfm
Slide 21: Megakaryocyte, 12/30/06, http://www.meded.virginia.edu/courses/path/innes/nh/platelets.cfm