Blood
Erythrocyte
transports oxygen
Basophil
0.5-1% WBCs;
inflammatory &
allergic rxns
Eosinophil
2-4% WBCs;
anti-helminth and
phagocytic actions
Lymphocyte
20-25% WBCs;
specific immune rxns,
B & T cells
Monocyte
3-8% WBCs;
becomes macrophage phagocytic activity
Neutrophil
60-70% WBCs;
major phagocyte
antibacterial defenses
Characteristics of Blood:
A. Temperature: approx. 38oC
B. pH: 7.35-7.45
C. Ave. Volume: 5-6 liters (11 pints)
D. Amount/Body Weight: 8% of body weight
E. Composition:
1. 55% Liquid portion
2. 45% Formed elements
Soluble Components of Blood:
A. Serum (liquid portion without clotting factors)
B. Plasma (liquid portion + clotting factors)
1. Plasma contains many sorts of proteins including albumins, globulins, clotting factors, complement, regulatory enzymes, as well
as electrolytes and hormones.
2. Albumins: most abundant plasma proteins; carriers for many molecules (sterols, bilirubin, hormones, ions...)
3. Globulins: many different types of proteins including immunoglobulins and...
a. alpha1-anti-trypsin (AAT): major globulin; inactivates proteases; important in counteracting endogenous proteolytic
activity such as during coagulation, inflammation; AAT-deficency associated with emphysema and liver disease;
b. Haptoglobulin: binds free hemaglobin from lysed RBCs; increases under stress, acute inflammation, infections; decreases
with massive hemolysis, burns, transfusion mismatches
c. Transferrin: binds free Fe3+, transports in blood,
III. Blood cells (Formed Elements): All blood cells are produced in red bone marrow
A. Erythrocytes: produce about 2.5 million/sec; 120 day lifespan
1. Reticulocytes: immature RBCs (>1%)
2. Hematocrit = % RBC in blood (volume); male = 40-54%; female = 38-46%
3. Anemia: decreased hematocrit; many forms and causes:
a. Iron-deficiency anemia: most common, inadequate iron absorption or excessive excretion
b. Pernicious anemia: lack of intrinsic factor needed for B12 absorption
c. Hemolytic anemia: destruction of RBCs leaving "ghosts"
d. Thalassemia: inherited form of hemolytic anemia - altered form of Hb
e. Aplastic anemia: loss of erythropoesis in red bone marrow
f. Sickle-cell anemia: misshapen RBCs from altered Hb causes poor vascular circulation and hemolysis
E. Polycythemia: increased hematocrit (over 65%); may be spurious or secondary to renal disease
F. Erythropoetin: hormone to stimulate RBC synthesis; given to counteract bone marrow deficits (chemoth.)
G. Erythrocyte and Hemoglobin (Hb) Production and Recycling:
1. Spleen, liver, red bone marrow - macrophage phagocytize damaged/dead RBCs;
globin & heme are separated;
globin digested & amino acids recycled;
2. The Fate of Heme... >
a. Fe3+ separated from heme ---> biliverdin ---> bilirubin ---> into blood to liver
b. bilirubin added to bile into small intestine...
c. bilirubin ---> urobilinogen in lrg int. ---> into kidney
(excreted as urobilin) or lrg int. (excreted as stercobilin)
3. The Recycling of Fe3+...
a. Fe3+ bound by transferrin ---> into blood ---> transport to liver...
b. stored in the "F &H Wharehouse" (ferritin & hemosiderin) to be used later...
c. bound again to transferrin ---> into blood to bone marrow for new Hb synthesis.
H. Factors required for RBC synthesis:
1. Fe3+: necessary diet nutrient
2. Vit B12: used for erythropoeisis in red bone marrow
3. Intrinsic factor: produced by stomach parietal cells - aids Vit B12 absorption in small intestine
4. Erythropoetin: hypoxia induces kidneys to increase erythropoetin secretion
5. Protein: amino acids used to produce globin
Leukocytes:
A. Granulocytes:
1. Neutrophils (50-70%); 3 day lifespan; major phagocyte & granulocyte; attracted by inflammatory factors and complement;
granules with hydrolytic enzymes; cell dies after degranulation/phagocytosis
a. Neutrophilia: increase %; common with acute bacterial infections
b. Neutropenia: decrease %; common with anemias, viral infections, radiation/chemotherapy;
i) Neutropenia can result in lowered immune protection especially to bacterial/fungal infections.
2. Eosinophils (2-4%); major anti-helminth protection (myelin basic protein released); also contributes to some hypersensitivity
reactions and phagocytosis of bacteria.
3. Basophils (<1%); granulocytic, nonphagocytic; major inflammatory cell, releases histamines, proteases and granulocyte-attracting
factors.
4. Monocytes (2-8%); only last 8-12 hrs in circ. then migrate to tissue = major function to become macrophage in tissue; play key
role in "antigen presentation", express MHC-II.
5. Platelets (thrombocytes) (240-400,000/mm3); crucial to help activate blood clot formation, for platelet plug; spleen acts as
reserve site;
6. Lymphocytes (20-30%) mononuclear cells; mediate/regulate specific immune responses (antibody formation, anti- viral and antitumor protection)
a. B-cell: produce immunoglobulins (mature in bone marrow)
b. T-cell: activate/regulate B-cells, major immune regulatory cells (mature in thymus)
c. NK cell: natural killer cell; non-specific anti-tumor cytolytic cell
Major Blood Group Antigens:
A. ABO Antigens
Individuals with Type A blood contain antibodies to Type B blood (anti-B antibodies)
Individuals with Type B blood contain antibodies to Type A blood (anti-A antibodies)
Individuals with Type AB blood contain no antibodies to either Type A or Type B blood
Individuals with Type O blood contain antibodies to both Type A or B blood (anti-A and anti-B antibodies)
B. Inheritance of Blood Types
If person with AB blood and O blood have children, a Punnett square illustrates possible offspring blood types:
A
B
i
Ai
Bi
i
Ai
Bi
This shows 50% offspring will be A i (A blood type) and 50% will be B i (B blood type)
More Examples:
Parents:
heterozygous B type
heterozygous A type
Parents:
homozygous A type
AB type
B
i
A
AB
Ai
i
Bi
ii
Offspring:
25% AB type
25% A type
25% B type
25% O type
Parents:
heterozygous B type
heterozygous B type
A
A
A
AA
AA
B
AB
AB
Offspring:
50% A type (homozyg.)
50% AB type
B
i
B
BB
Bi
i
Bi
ii
Offspring:
25% B type (homozyg.)
50% B type (heterozyg.)
25% O type
C. ABO Compatibility in Blood Transfusions
Individuals with Type A blood contain antibodies to Type B blood (anti-B antibodies)
Individuals with Type B blood contain antibodies to Type A blood (anti-A antibodies)
Individuals with Type AB blood contain no antibodies to either Type A or Type B blood
Individuals with Type O blood contain antibodies to both Type A or B blood (anti-A and anti-B antibodies)
This table summarizes ABO tranfusion compatability:
Donor blood type:
Can safely donate to:
Recipient blood type:
Can safely receive blood from:
A
A or AB
A
A or O
B
B or AB
B
B or O
AB
AB only
AB
A, B, AB or O
O
A, B, AB and O
O
O only
Rh+
Rh+ only
Rh+
Rh+ or Rh-
Rh-
Rh+ or Rh-
Rh-
Rh- only
D. Rh Antigen
Rh expression is designated as Rh + (thus A+ blood has expression of A and Rh)
Lack of Rh expression is designated as Rh - (thus B - blood has expression of B but no Rh)
Important for Rh- mother pregnant with Rh+ child
Sensitization of mother during delivery induces high levels of anti-Rh IgG antibodies; (block with Rhogam)
During pregnancy with subsequent Rh+ child, anti-Rh IgG can cross placenta and cause hemolytic disease of newborn (less problem
if Rhogam is administered during first delivery)
Transfusions are typically restricted to matching Rh+ donor to Rh+ recipient.
Rh - recipients should not be given Rh+ blood transfusion.
Rh - blood can be transfused into Rh- or Rh+ recipient. (much like O blood can be given to any blood type)
"Universal Donor" = O -
"Universal Recipient" = AB +
E. Blood Typing
A small sample of blood is mixed with known reagents containing anti-A, or anti-B or anti-Rh.
A positive reaction is where clumping (agglutination) occurs (antibody binds to RBCs in the blood)
A negative reaction is where no agglutination occurs (antibody does not bind to RBCs)
Severe (life-threatening) mismatch transfusion reactions can occur if donor and recipient do not match ABO type