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PowerPoint® Lecture Slides
prepared by
Janice Meeking,
Mount Royal College
CHAPTER
17
Blood
Modified by:
Olga E. Vazquez
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Cardiovascular System
• Cardio = heart
• Vascular = blood vessels
• Consists of three interrelated components:
• Blood
• Heart
• Blood vessels
• We will now examine the blood.
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Topics Discussed Today
• Blood as connective tissue
• Physical characteristics and volume of blood
• Functions of blood
• Blood components
• Plasma
• Formed elements
• Hematopoiesis
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Blood
• Blood is unique from person to person
• Health care professionals routinely examine
and analyze its differences through various
blood tests to determine the causes of
different diseases.
• Hematology = study of blood
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Blood: An Overview
• Blood is the only fluid tissue in the
body.
• Even though it might seem like a
homogeneous liquid, the microscope
reveals 2 components:
• Cellular component
• Liquid component
• What type of tissue is blood classified
as?
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Blood: An Overview
• Blood is a specialized type of connective
tissue in which living blood cells, the formed
elements (cells), are suspended in a nonliving
fluid matrix called plasma.
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Blood: An Overview
• Blood cells carry oxygen and nutrients to our body’s
tissues, and remove Carbon Dioxide and other
wastes, and take them to places to be removed from
the body.
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Physical Characteristics and Volume
• Total blood volume: 8%
of body weight
• Average volume in
healthy males:
• 5-6 L (~ 1.5 gallons)
• Average volume in
healthy females:
• 4-5 L (1.05 to 1.32
gallons)
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Physical Characteristics and Volume
• Blood is more dense than water and about
5 times more viscous. Why?
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Viscosity
• Although plasma is mostly water, it also contains
other molecules such as electrolytes, proteins
(especially albumin and fibrinogen), and other
macromolecules.
• The addition of formed elements to the plasma
(red cells, white cells, and platelets) further
increases the viscosity. Of these formed
elements, red cells have the greatest effect on
viscosity under normal conditions.
• Temperature
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Functions
• Blood performs a number of functions, all
concerned in one way or another with:
• Distribution
• Regulation
• Protection
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Functions
• There are six functions:
1. Transportation
• O2 lungs → cells
• CO2 cells → lungs
• Nutrients → cells
• waste from cells → kidneys (excretion!)
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Functions
2. Defense
• White blood cells – fight disease
• blood proteins – antibodies (identification)
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Functions
3. Temperature regulation - absorbs and distribute
heat throughout body and skin
4. Prevents loss of blood – blood clots
5. Hormone movement – endocrine gland → cells
6. Regulates pH (our acid/base balance in our
bodies) – through buffers
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Components of Blood
• If a sample of blood is spun in a centrifuge, the
heavier formed elements are packed down by
centrifugal force and the less dense plasma
remains at the top.
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Components
• Bottom – erythrocytes
(what are they?)
• Erythro = red
• Buffy coat – whitish layer
present at the erythrocyteplasma junction
• Contains platelets and
leukocytes (white blood
cells)
• Plasma
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Plasma
• Makes up 55% of blood
• Although is made up of
about 90% water,
plasma contains over
100 different dissolved
solutes including gases,
hormones, waste, etc.
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Plasma
• Contains proteins
• Contains electrolytes
• Contains wastes to be taken away
• Contains water
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Components of Whole Blood
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Formed Elements
• The formed elements are
present in the buffy coat
and the bottom red layer.
• In other words the
formed elements are the
red blood cells, white
blood cells, and platelets
(platelets help form clots)
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Components of Whole Blood
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Figure 17.2
Formed Elements
• These cells have unusual features.
• Two of the three are not even true cells. Why?
• RBC’s have no nuclei or organelles, and
platelets are cell fragments. Only leukocytes are
true cells
• Most of the formed elements survive in the
bloodstream for only a few days.
• Most blood cells do not divide.
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Formed Elements
• Erythrocytes normally
constitute 45% of the total
volume of blood.
• This percentage is known
as hematocrit (“blood
fraction”).
• In males and females, this
percentage might differ:
• males: 47% ± 5%
• females: 42% ± 5%
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Formed Elements
• RBC or erythrocytes are involved in gas
transport
• Carry O2
• Carry 20% of CO2
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Formed Elements
• WBC or leukocytes have
many specialized
functions. Together with
platelets, leukocytes
contribute less than 1% of
blood volume.
• Immunity
• T cells, B cells,
neutrophils, macrophages
• Most abundant –
neutrophils
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Formed Elements
• Platelets
• Cell fragments
• Encourage clot formation
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Formed Elements Formation
• Hematopoiesis (hemato = blood, poiesis = to
make)
• Process in which formed elements of the blood
develop
• Erythropoiesis
• Leukopoiesis
• Before birth it occurs
• Yolk sac
• Later in the liver, spleen, thymus and lymph nodes
• Last 3 months of gestation in the red bone marrow
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Hematopoiesis
• During childhood (up to 5
years) occurs in the
epiphysis of almost all long
bones.
• In adults it occurs also in flat
and irregular bones such as
the skull, sternum, hip bone,
ribs, and vertebra.
• Formed element production
in adult’s long bones occurs
in the humerus and femur.
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Checking Understanding
• Explain why blood is classified as a connective tissue
• What is the average blood volume in human adult?
• What are the two components of the blood?
• Why blood is more viscous than water?
• List three major functions of blood and provide an example of
each.
• Name the formed elements. Why are they elements instead of
cells?
• What is the hematocrit? What is the normal value?
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Red Blood Cells
• Erythrocytes
• Erythro =
• Cyte =
• The erythrocyte is an excellent example of
complementarity of structure and function.
• Each structural characteristic contributes to its
gas transport functions.
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Structural Characterstics
• Its small size and
biconcave shape
provides 30% more
surface area than other
spherical cells. Why is
this important?
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Structural Characteristics
• No nucleus (anucleate) or
organelles
• The red blood cell carries a
protein called “hemoglobin”
that carries the oxygen to our
body parts.
• Hemoglobin is made partly
with iron.
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Structural Characteristics
• Major function of RBC is to
transport hemoglobin.
• Erythrocytes are over 97%
hemoglobin. This is why RBC
could be called “bags” of
hemoglobin.
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Hemoglobin
• It’s the protein that makes RBC red.
• Binds easily and reversibly to oxygen
• Oxygen moves in the blood bound to
hemoglobin
• Normal values of hemoglobin
• 14-20 g/100ml in infants
• 13-18 g/100ml in adult males
• 12-16 g/100ml in adult females
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Hemoglobin
• A single RBC contains about 250 million
hemoglobin molecules.
• So, each RBC can hold about 1 billion
molecules of O2.
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Erythropoiesis
• Erythropoiesis needs to be controlled so there is
a balance between RBC production and
destruction.
• New cells are made at a rate of more than 2
million per second in healthy people.
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Erythropoietin
• Hormone effects:
• Hormones produced in the kidney and liver
• Stimulates red bone marrow to increase rate of
cells
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Homeostasis: Normal blood oxygen levels
1 Stimulus:
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
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Figure 17.6, step 1
Homeostasis: Normal blood oxygen levels
1 Stimulus:
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
2 Kidney (and liver to
a smaller extent)
releases
erythropoietin.
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Figure 17.6, step 2
Homeostasis: Normal blood oxygen levels
1 Stimulus:
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
2 Kidney (and liver to
3 Erythropoietin
a smaller extent)
releases
erythropoietin.
stimulates red
bone marrow.
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Figure 17.6, step 3
Homeostasis: Normal blood oxygen levels
1 Stimulus:
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
4 Enhanced
erythropoiesis
increases RBC
count.
2 Kidney (and liver to
3 Erythropoietin
a smaller extent)
releases
erythropoietin.
stimulates red
bone marrow.
Copyright © 2010 Pearson Education, Inc.
Figure 17.6, step 4
Homeostasis: Normal blood oxygen levels
1 Stimulus:
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
5 O2- carrying
ability of blood
increases.
4 Enhanced
erythropoiesis
increases RBC
count.
2 Kidney (and liver to
3 Erythropoietin
a smaller extent)
releases
erythropoietin.
stimulates red
bone marrow.
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Figure 17.6, step 5
Analyzing
• How might your hematocrit change if you
move from a town at sea level to a high
mountain village?
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Destruction of Erythrocytes
• Red blood cells have a useful life span of 100
to 120 days, after which they become trapped
and fragment in smaller circulatory channels,
particularly in those of the spleen.
• In the red pulp of the spleen, RBC rupture when
they try to squeeze through because of their
fragile old membrane.
• For this reason, the spleen is sometimes called
the “red blood cell graveyard
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Anemia
• Any decrease in blood’s oxygen-carrying
capacity is known as anemia.
• Causes:
• Insufficient number of RBC
• Low hemoglobin content
• Abnormal hemoglobin
• One of the major effects of anemia is the greatly
increased work load on the heart.
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Human Blood Groups
• RBC’s have antigens (identifiers) on them.
• The presence or absence of these antigens
tell us what blood type we have.
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Markers on RBC
• If there are no blood type
antigens, you have type O
blood.
• If you have B type antigens,
you have type B blood.
• If you have A type antigens,
you have A type blood.
• What about people with type
AB blood?
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People that carry
the “D” antigen
are Rh +. If they
do not have the
antigen, they are
Rh-
ABO Markers
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Rh Factor
• There are 45 different types of Rh agglutinogens.
• Three of which (C, D, and E) are common
• About 85% of Americans are Rh positive, which
means they carry the D antigen.
• Presence of the Rh agglutinogens on RBCs is
indicated as Rh+
• As a rule, a person’s ABO and Rh blood groups
are reported together, for example, O+, A-, and
so on.
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Rh Factor and Pregnancy
• Rho GAM
• Injection of anti-Rh antibodies given soon after
every delivery, miscarriage, abortion-binds
• Inactivates fetal Rh antigens so mother’s
immune system doesn’t respond
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Checking Your Understanding
• What is the main function of RBC?
• What organ is the red blood cell graveyard?
• Mrs. D has type A blood and is Rh+. So, she has A+
blood. What antigens (ID markers) are carried on her
blood?
• Mrs. D’s husband has type A- blood. What does this
mean?
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