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Chapter 10 - Blood
• The only fluid tissue in
the human body
• Classified as a complex
connective tissue
• COMPONENTS:
– Living cells = formed
elements (RBC, WBC,
Platelets)
– Non-living fluid matrix
= PLASMA (straw
colored)
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Physical Characteristics of Blood
• Color range
– Oxygen-rich blood is scarlet red
– Oxygen-poor blood is dull red (NOT BLUE)
• Sticky, opaque, with a metallic taste
• Blood accounts for approx. 8% of your body
weight
• Volume in healthy men = 5.6 Liters (6 quarts)
• pH must remain between 7.35–7.45
• Blood temperature is slightly higher than body
temperature at about 100.4 degrees F
• Heavier than water & 5x thicker (VISCOUS)
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Blood Plasma
• Liquid part of blood - Composed of
approximately 90% water
• Includes many (over 100) dissolved
substances
– Nutrients,Salts (electrolytes),Respiratory gases
– Hormones, Plasma proteins made by liver, Waste
products
• Carries the Formed Elements
– Erythrocytes = Red blood cells (RBC)
– Leukocytes = White blood cells (WBC)
– Platelets = Cell fragments
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Plasma Proteins-Most abundant solutes
in plasma
• Albumin – Regulates osmotic pressure
(helps to keep water in the bloodstream)
• Clotting proteins – Help to stop blood
loss when a blood vessel is injured
• Antibodies – Help protect the body from
pathogens
• *When blood protein levels drop the liver is
stimulated to make more proteins*
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Photomicrograph of a Blood Smear
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Figure 10.2
Characteristics of Formed Elements of the Blood
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Table 10.2
Characteristics of Formed Elements of the Blood
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Table 10.2
Erythrocytes (Red Blood Cells)
• The main function is to carry oxygen to the cells
of the body
• Anatomy of circulating erythrocytes
– Biconcave disks
– Essentially bags of hemoglobin
• HEMOGLOBIN- Iron bearing protein that
Transports oxygen
– Anucleate (no nucleus)
• Outnumber white blood cells 1000:1
• Stay inside blood vessels
• Contain no mitochondria, use anaerobic
respiration
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Hemoglobin
• Iron-containing protein
• Binds strongly to oxygen
• Each erythrocyte (RBC) has 250 million
hemoglobin molecules
• Each RBC can carry 1 billion molecules of oxgen
Homeostatic Imbalances
1) Anemia – Decrease in the
oxygen-carrying ability of the
of the blood.
2) Sickle Cell Anemia (SCA) –
Genetic defect leads to
abnormal hemoglobin which
becomes sharp and
produces a sickle shaped
RBC.
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Leukocytes (White Blood Cells)
• Crucial in the body’s defense against
disease
• These are complete cells, with a nucleus
and organelles
• Able to move into and out of blood vessels
(diapedesis)
• Can respond to chemicals released by
damaged tissues or infection (positive
chemotaxis)
• Can move by amoeboid motion
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Leukocyte Levels in the Blood
• Normal levels are between 4,000 and 11,000 cells per
millimeter cubed.
• Abnormal leukocyte levels
– Leukemia “White Blood”
• Bone marrow becomes cancerous
• Huge #’s of WBC’s are produced at a rapid pace but are
immature and ineffective
– Leukocytosis (Normal response to infectious threats)
• Above 11,000 leukocytes/mm3
• Generally indicates an infection (bacterial or viral) in body
– Leukopenia
• Abnormally low leukocyte level
• Commonly caused by certain drugs (corticosteriods &12
anticancer agents)
Types of Leukocytes
• Granulocytes
– Granules in their
cytoplasm can be
stained
– Include neutrophils,
eosinophils, and
basophils
• Agranulocytes
– Lack visible cytoplasmic
granules
– Include lymphocytes
and monocytes
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Granulocytes
• Neutrophils
– Multilobed nucleus with fine granules
– Active phagocytes at active sites of
infection
– Increase rapidly during short term
infection
• Basophils
– Have histamine-containing granules
(vasodilators)
– Initiate inflammation
• Eosinophils
– Large brick-red cytoplasmic granules
– Found in repsonse to allergies and
parasitic worms
– Play a complex role in allergy attacks
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Agranulocytes
• Lymphocytes (B & T)
– Nucleus fills most of the cell
– B produce antibodies
– T involved in graft rejection,
fighting tumors and viruses
via direct cell attack.
• Monocytes
– Largest of the white blood cells
– Function as active phagocytes
that eventually become
macrophages in tissues (Longterm “clean up team”)
– Important in fighting chronic
infection (Ex. Tuberculosis)
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Platelets
• Not considered complete cells but cell fragments
• Derived from ruptured multinucleate cells
(megakaryocytes)
• Needed for the clotting process
• Normal platelet count = 300,000/mm3
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Hematopoiesis
• Blood cell formation
• Occurs in red bone
marrow (epiphyses of
humerus and femur)
• All blood cells are derived
from a common stem cell
(hemocytoblast)
• Hemocytoblast
differentiation
– Lymphoid stem cell
produces lymphocytes
– Myeloid stem cell produces
other formed elements
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Fate of Erythrocytes
• Young RBC’s have a nucleus, the DNA directs
the formation of hemoglobin.
• Once mature, organelles are ejected.
• Unable to divide, grow, or synthesize proteins
(no DNA)
• Wear out in 100 to 120 days, become rigid and
fall apart
• When worn out, are eliminated by phagocytes in
the spleen or liver
• Lost cells are replaced by division of
hemocytoblasts
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Control of Erythrocyte Production
• Rate is controlled by a hormone (erythropoietin)
• Kidneys produce most erythropoietin as a
response to reduced oxygen levels in the blood
• Homeostasis is maintained by negative
feedback from blood oxygen levels
• Leukocytes (WBC’s) & Platelets are stimulated
by colony stimulating factors (csf) and
interleukins.
• Thrombopoeitin also stimulates an increase of
platelets.
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Control of Erythrocyte Production
Figure20
10.5
Hemostasis
• Stoppage of blood flow
• Result of a break in a blood vessel
• Hemostasis involves three phases
1. Vascular spasms- Immediate response is
vasoconstriction. They narrow the blood
vessel decreasing blood less.
2. Platelet Plug Forms- Platelets become
“sticky” and cling to the damaged site.
3. Coagulation – Meshwork of fibrin forms the
basis of the clot.
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Blood Clotting
• Blood usually clots within 3 to 6 minutes
• The clot remains as endothelium regenerates
• The clot is broken down after tissue repair
Fibrin Clot
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Homeostatic Imbalances in Clotting
• Thrombus
– A clot in an unbroken blood vessel, often legs
– Can be deadly in areas like the heart
(coronary thrombosis)
• Embolus
– A thrombus that breaks away and floats freely
in the bloodstream
– Can later clog vessels in critical areas such as
the brain (cerebral embolus may = stroke)
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Bleeding Disorders
• Thrombocytopenia
– Platelet deficiency
– Even normal movements can cause bleeding from
small blood vessels that require platelets for clotting
– Petechiae – small purplish blotches on skin
– May be caused by decrease in vitamin K –
needed for clotting factors or from any
condition that suppresses the bone marrow.
• People at risk for clots monitor K levels
• Hemophilia- “bleeder’s disease”
– Hereditary bleeding disorder
– All normal clotting factors are missing
– Given transfusions of fresh plasma or purified
clotting factors.
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Blood Groups and Transfusions
• Large losses of blood have serious
consequences
– Loss of 15 to 30 percent causes weakness
– Loss of over 30 percent causes shock, which can be
fatal
• Transfusions are the only way to replace blood
quickly
• Transfused blood must be of the same blood
group
• Blood can be stored for approximately 35 days
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Human Blood Groups
• Blood contains genetically determined
proteins (antigens) embedded in the
plasma membranes of RBC’s
• A foreign protein (antigen) may be
attacked by the immune system
• Blood is “typed” by using antibodies found
in plasma that will cause blood with certain
proteins to clump (agglutination)
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Human Blood Groups
• There are over 30 common red blood cell
antigens (proteins)
• The most vigorous transfusion reactions
are caused by ABO and Rh blood group
antigens
• Mis-match can lead to severe kidney
damage and shutdown
• Not immediately fatal
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ABO Blood Groups
• Based on the presence or absence of two
antigens (inherited from Mom and Dad)
– Type A – Genes are AA or AO
– Type B – Genes are BB or BO
– Type AB (co-dominant) – Genes are AB
• The lack of these antigens is called
type O (recessive) – Genes are OO
• Antibodies form against the antigens not present
in the blood.
– Example: Type A blood has RBC’s with the A antigen
and Anti-B Antibodies
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Rh Blood Groups
• Named because of the presence or absence of
one of eight Rh antigens
• Determines whether the blood type is positive or
negative.
• Most Americans are Rh+ (RBC’s carry the Rh
antigen)
• Problems can occur in mixing Rh+ blood into a
body with Rh– blood
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Rh Dangers During Pregnancy
• Danger is only when the mother is Rh–
and the father is Rh+, and the child inherits
the Rh+ factor
• The mismatch of an Rh– mother carrying
an Rh+ baby can cause problems for the
unborn child
– The first pregnancy usually proceeds without
problems
– The immune system is sensitized after the
first pregnancy
– In a second pregnancy, the mother’s immune
system produces antibodies to attack the Rh+
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blood (hemolytic disease of the newborn)
Blood Typing
• Blood samples are mixed with anti-A and
anti-B serum
• Coagulation or no coagulation leads to
determining blood type
• Typing for ABO and Rh factors is done in
the same manner
• Cross matching – testing for agglutination
of donor RBCs by the recipient’s serum,
and vice versa
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Blood
Typing
Universal donor
is OUniversal
receiver is AB+
Figure34
10.8
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Developmental Aspects of Blood
• Sites of blood cell formation
– The fetal liver and spleen are early sites of blood cell
formation
– Bone marrow takes over hematopoiesis by the seventh
month
• Fetal hemoglobin differs from hemoglobin
produced after birth - it has a greater ability to pick
up oxygen
• Fetal Hb is broken down & replaced with regular
RBC’s
• Jaundice results in the inability to beak down the
Hbf quickly enough. If untreated can cause brain
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damage, lights and sunshine is the treatment.
Homeostatic Imbalances
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