Blood
Hematology
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BLOOD: actually is a specialized CT with
intercellular material comprised entirely of
fluid.
formed from undifferentiated mesenchyme of
embryos (similar to other CT)
- contains formed elements (blood cells) and
plasma
1. In average human blood formed elements
comprise 46% of blood volume, plasma 54%
(hematocrit or pcv- packed cell volume)
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Men: 40-50% (5-6 million RBC's/mm3)
Women: 35-45% (4-5 million RBC's/mm3)
2. Blood volume in average human about 5 L (8%
of body weight)
3. Formed elements include: erythrocytes (RBC),
leukocytes (WBC), platelets (thrombocytes
which are cell fragments from megakaryocyte).
Origin of blood:
Blood cells originate in red bone marrow
from hematopoietic stem cells (pluripotent or
hematocytoblasts). These in turn will
differentiate (progenitor cells) into the
specialized blood cells.
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Erythropoietin (EPO): Hormone produced
in the kidneys used to stimulate
erythropoiesis in the bone marrow.
EPO is produced in response to:
- hypoxia
- decrease in rbc count
- decrease in hemoglobin conc.
Anemia
Refer to handout on common anemia's
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Blood:
pH- 7.35-7.45 (arterial blood)
- slightly alkaline
4-5x more viscous than water
Blood temp. approx. 100F.
Salt conc. .85-.90% (Saline?)
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Erythrocytes (RBC’s)
Erythropoiesis: begin as immature
proerythroblasts which in turn mature to a
reticulocytes and ultimately an
erythryocyte.
Adult RBC production is approximately 200
billion RBC's /day. This means that RBC's
are produced at the astonishing rate of 2
million/sec in healthy adults.
RBC's outnumber WBC's about 800 to 1
Female: RBC count is 4-5 million/mm3
Male: RBC count is about 5-6 million/mm3
Characteristics:
- anucleated
- 7.5 micrometers in diameter
- lacks other subcellular organelles as well
- biconcave shaped (allows a 20-30% increase
in surface area which increases
efficiency of O2 and CO2 transport)
- life span of 120 days
The protein spectrin allows cell to flex and
change shape to squeeze through capillaries.
- Ability to carry O2 and CO2- hemoglobin
Hemoglobin (Hb):
- Protein found in rbc’s that bind O2.
- Imparts reddish color to rbc.
- Hemoglobin (Hb) in g/100 mL of blood
 13-18 g of hemoglobin/100 mL of blood in adult
males
 12-16 g of hemoglobin/100 mL of blood in adult
females
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- Hb contains a structure called the porphyrin ring
(also called heme) that is bound to a centrally
located Fe molecule.
- Each Hb can carry 4 O2's. One RBC contains 250
million Hb molecules (ie. 1 RBC can carry as
many as 1 billion molecules of O2).
- O2 is picked up in the lungs and binds to Hb
along with H+. Hb is now called oxyhemoglobin
(bright red arterial blood).
- When O2 is dumped off in the tissues it is called
deoxyhemoglobin.
- When Hb picks up CO2 from tissues it binds to
the protein portions of the Hb. Hb carrying CO2
is called carbaminohemoglobin. This gives
venous blood its bluish color. Venous blood is
not blue due to the decrease in O2 in the blood.
Life cycle of an RBC
1- Nutrients (folic acid, Fe and Vit. B-12) are
absorbed in the small intestine.
2- Nutrients go to red bone marrow
3- RBC’s develop from progenitor cells
4- RBC’s released in bloodstream and circulate for
approx. 120 days
5- After 120 days, RBC’s are broken down by
macrophages in the liver and spleen
6- Hb is broken down into heme and globin
7- Heme decomposes into Fe and a greenish
substance called biliverdin
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8- Iron binds to a protein called transferrin
which ultimately travels to the red bone
marrow to be recycled. (80% of Fe in the
body is stored in the liver as ferritin)
9- Some biliverdin is converted to bilirubin,
as yellowish/orange pigment found in bile
–gallbladder.
10- Bilirubin travels into small intestine and
10 % is metabolized to urobilinogen
(urochromes filtered in the liver)
11- 90% of bilirubin exits in the feces giving
fecal matter its brown color (stercobilin)
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RBC’s do not have mitochondria so they
obtain their energy from anaerobic
glycloysis (produce ATP)
- primary component in this pathway is
2,3 diphosphoglycerate (2,3 DPG)
- assists in unloading O2 in the tissues
from the Hg in the RBC
Leukocytes (WBC’):
- Contain a nucleus plus all common organelles
- 5,000-10,000/mm3 lab values
- Have the ability to move once outside the blood
(diapedesis) through fenestrations (holes) in the
capillaries
- Ability to be attracted to chemicals (chemotaxis)
- Grouped according to the presence of granules
in their cytoplasm (Chasing bacteria)
Granular leukocytes/ granulocytes/ myeloblast
series cells/ polymorphonuclear cells (PMN’s)
- Neutrophils
- Basophils
- Eosinophils
Agranular leukocytes (agranulocytes):
- Monocytes
- Lymphocytes
WBC’s are involved in immune functions and
are primarily active outside the blood
stream.
To remember granulocytic and agranulocytic
“Every Boy Needs Mommies Love”
To remember percentage of proportion
“Never Let Monkeys Eat Bananas”
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NEVER: neutrophils (60%)
LET: lymphocytes (30%)
MY: monocytes (5%)
ENGINE: eosinophils (4%)
BLOW: basophils (0-1%)
Neutrophil (lobed)
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Neutrophils:
2-5 lobes that are interconnected by fine strands
(sometimes called “segs”)
- acute inflammatory response and phagocytize
bacteria, fungi and some viruses
- circulate in blood for short period of time (10
hrs.) before migrating into tissues (5 days).
- first white cell on the scene of an infection
Neutropenia: too few neutrophils
Neutrophilia: too many neutrophils
Basophil
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Basophils:
Nucleus is typically bilobed
Granules contain histamine and heparin
Little ameboid and no phagocytic activity
when basophil stimulated by an antigen or by
tissue injury, responds by
breaking open granulations causing histamine
release. Histamine release initiates inflammatory
reaction causing vasodilation and increasing
permeability of blood vessels.
- erythema
- heat
- plasma release
Eosinophil
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Eosinophil
nucleus usually bilobed
High number present in an allergic
reaction.
Phagocytize and kill larval stage of
parasitic worms.
Phagocytosis of the Ab/Ag complex found
in an immune response
Lymphocytes:
- 30% of WBC population
- Large dark purple nucleus
- Small, medium and large
- Majority are not found in circulating blood but in
lymphoid tissue (nodes, spleen, marrow etc..)
- Smallest WBC slightly larger than RBC
- T- lymphocytes (immune response)
- B- lymphocytes (antibodies-immunoglobins)
We will cover these two lymphocytes in much detail
under immunology
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Lymphocyte
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Monocytes:
Largest of the WBC’s
Nucleus is indented
monocytes are phagocytic
when monocytes leave bloodstream they rapidly
transform to macrophages that are very active
in ingesting bacteria, dead
cells, tissue debris (“wandering macrophages”)
Uses filopodia to search for things to eat
- cytoplasmic extensions
stimulate antibody production by lymphocytes.
Monocyte
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Platelets:
Not cells but cell fragments
Hemocytoblast Megakaryoblast
Megakaryocyte
150,000 to 400,000/mm3
Anucleated
Aid in blood clotting
Arise from megakaryocytes in red bone marrow
granulated: granules contain serotonin that aid
in vasoconstriction
Form a temporary plug when vessel is damaged.
Formation is regulated by a hormone called
thrombopoietin
Platelets
Plasma vs. serum:
Plasma is an aqueous (92% water), straw colored
solution containing proteins, lipids (digested
nutrient), blood gases (O2, CO2 and N2), aminoacids, vitamins, hormones, and electrolytes (i.e.
Na and Cl).
The main plasma proteins are:
1- gamma globulins (immunoglobulins or
antibodies)- lymphoid tissue
2- albumins (maintains osmotic pressure of
blood) - liver
3- fibrinogen (clotting agent)- liver
To obtain plasma, blood sample is spun down with
an anticoagulant in the tube
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Serum:
If blood is allowed to clot, the clear yellow
liquid that separates out is called serum.
Serum is similar to plasma but lacks
fibrinogen and other clotting agents.
To obtain serum, blood sample is spun
down with no anticoagulant in the tube.
Normal lab values of common substances
dissolved in blood plasma/serum.
Glucose: 70-110 mg/dl (fasting)
Sodium (Na): 135 - 145 mEq/L
Calcium (Ca): 8.5- 10.5 mEq/L
Chloride (Cl): 98-106 mEq/L
Potassium (K): 3.5 - 5.0 mEq/L
Bicarbonate (HCO3): 18-23 mEq/L
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Hemostasis- blood stoppage
Initial goal is to turn liquid (blood) into gel
(coagulation).
Steps:
1- smooth muscle in blood vessel wall
contracts when vessel is damaged
(vasospasm)
-decrease blood loss, may seal off
opening
- slower flow of blood also helps
platelets & coagulation.
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2- attracted & stick to damaged vessel walls & to
other sticky platelets
-platelets release attractant chemicals that
attracts other platelets
-platelets release thrombospondins that aid
platelet adhesion
- platelet plug
3- Blood coagulation: Cascade of blood clotting
chemicals.
To form a blood clot a soluble plasma protein,
fibrinogen (factor I), must be converted to
insoluble threads called fibrin.
Prothrombin (factor II) is a protein made in the
liver and is a normal part of blood plasma.
a. Prothrombin is converted to thrombin (factor II
a).
b. Thrombin fragments fibrinogen.
c. Fibrinogen joins to form long slender threads of
fibrin.
d. Fibrin threads attach to the damaged blood
vessels and more blood cells and platelets will
stick. This mesh will form a blood clot.
Under normal conditions clotting of blood in the
body should only occur if blood remains
stationary. Embolus vs. thrombus
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Blood typing (ABO):
Discovered in 1900 by Dr. Karl Landsteiner
A – antigen A (40%)
B – antigen B (10%)
AB – antigen A & B (universal recipient 5%)
O – no antigens (universal donor 45%)
In the plasma:
A: Antigen A in RBC
Plasma: anti-B type antibodies
B: Antigen B
Plasma: anti-A type antibodies
AB: antigen A&B
Plasma: no anti-A or anti-B antibodies
O: no antigens
Plasma: both anti-A and anti-B antibodies
Blood
Type
A
Type of
Antigen?
A antigen
Type of
Antibody?
Anti-B
Receive?
B
B antigen
Anti-A
B, O
AB
Both A and
B antigens
None
None
A, B, AB, O
Both Anti-A
and Anti-B
O only
O
A, O
Type O
Type B
45%
Type A
42%
Type AB
3%
10%
Rh factor (Antigen D)
Rh + = Rh factor antigen (marker) on RBC
(85%)
 Rh - = no Rh antigen
Rh- mother and Rh+ father: If baby
inherits Rh+ from dad, mom’s blood will
recognize baby’s blood as foreign and will
attack it.
- Erythroblastosis fetalis
Blood typing
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Blood Type Presence of Type of
Receive?
D Antigen? Antibody?
Rh Positive
Yes
None
+ and -
No
Anti-D
- only
Rh Negative