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The Blood
Chapter 10
Composition and Function of Blood Components
Blood:
Transports everything that is carried from one
place to another in the body – nutrients, wastes
and body heat.
It is the only true FLUID tissue in the body
because it has both solid and liquid components
It is a complex connective tissue in which living
blood cells are suspended in a non-living fluid
matrix called PLASMA
Plasma:
The non-living fluid make-up of the blood – the
liquid component
Composition and Function of Blood Components
Erythrocytes:
Thickened portion of blood when put through a
centrifuge will separate from the plasma and
appear as a red mass at the bottom of the tube
Buffy Coat:
Thin, whitish layer between the formed elements
of the blood plasma (separates is from the
erythrocytes) it contains:
Leukocytes: White blood cells – protect the body
Platelets: Cell fragments that help in the blood-clotting
process
Composition and Function of Blood Components
Hematocrit:
Percentage of total blood volume
45 % of which is erythrocytes
White blood cells and platelets are less than 1%
Plasma makes up the remaining 55%
Composition and Function of Blood Physical Characteristics and Volume
 Blood:
Sticky, opaque fluid
Color depends on the amount of oxygen that it is carrying
 Scarlet = oxygen rich
 Dull red = oxygen poor
Heavier than water and 5 x thicker (viscous) because of its
formed elements
It is slightly alkaline with a pH of 7.35-7.45
The temperature of blood is slightly higher than body
temperature at approx. 100.4˚F
It accounts for 8% of body weight and its volume is
approximately 5-6 liters
Composition and Function of Blood Plasma
Approximately 90% water and is the liquid
part of blood.
Contains dissolved substances such as:
Nutrients
Metal Ions
Respiratory gases
Hormones
Plasma proteins
Various wastes and products of cell metabolism
Composition and Function of Blood Plasma
Plasma Proteins:
Most abundant solute in plasma
Made by the liver
Serve a variety of functions:
Albumin: contributes to osmotic pressure of blood,
helping to keep water in the bloodstream, clot blood
vessels when blood is lost through an injured blood
vessel, antibodies protect the body from pathogens.
Composition and Function of Blood Plasma
Composition of plasma changes as cells
remove or add substances to the blood
Homeostatic mechanisms help to keep it
relatively consistent
Example: when blood proteins drop to a low level
the liver will become stimulated to create more
proteins and when it becomes to acid or to basic
the respiratory system and kidneys take action to
bring it back to its pH balance
Helps to distribute body heat evenly through
the body
Composition and Function of Blood Formed Elements
 Erythrocytes make up most of the formed elements
in blood
Consist of 4-6 million red blood cells
Transport oxygen and help to transport carbon dioxide
 Leukocytes:
4,000-11,0000 white blood cells
Responsible for body defenses and immunity
Consist of Basophils, Neutrophils, Eosinohil, Lymphocytes
and Monocytes
 Platelets:
250, 000-500,000
Responsible for blood clotting
Composition and Function of Blood Formed Elements
 Erythrocytes:
Red Blood Cells (RBC’s)
Carry oxygen in blood to all cells of the body
Anucleate: have no nucleus
They contain very few organelles
Mature RBC’s in the blood are sacs of hemoglobin
molecules
Hemoglobin: Iron containing protein transports bulk of
oxygen carried in blood
They lack mitochondria and make ATP by anaerobic
mechanisms and do NOT use any of the oxygen they
are transporting
Composition and Function of Blood Formed Elements
 Erythrocytes:
Small cells shaped like flat disks with an indented
center
Their small size and shape provide a large surface
area relative to volume and make them ideal for gas
exchange
RBC’s outnumber white blood cells by 1000 to 1 and
contribute greatly to blood viscosity
Normally we have approximately 5 million RBC’s per
cubic millimeter blood – when this number increases
the blood viscosity increases and when the number
decreases the blood viscosity decreases making the
blood thin and flow rapidly
Composition and Function of Blood Formed Elements
 Erythrocytes:
The amount of hemoglobin in the blood stream will
determine how well the erythrocytes can perform
oxygen transport
The more hemoglobin molecules the RBC’s have the
more oxygen they can carry
A single RBC contains 250 million hemoglobin
molecules each of which can bind 4 molecules of
oxygen enabling the RBC to carry approximately 1
billion molecules of oxygen!
Men have a slightly higher hemoglobin content than
women
Composition and Function of Blood Formed Elements
 Erythrocytes:
Anemia: a decrease in the oxygen carrying ability of the
blood. Can result from lower than normal RBC’s or
abnormal or deficient hemoglobin content in the RBC’s
Sickle Cell Anemia: genetic disorder. Abnormal
hemoglobin forms and becomes spiky and sharp when
the RBC’s unload oxygen or when oxygen content is
lower than normal. This deformity causes them to rupture
easily and block the small blood vessels interfering with
oxygen delivery and causing pain. It is most common in
black people who live or have ancestors who lived in the
malaria belt of Africa
Composition and Function of Blood Formed Elements
Erythrocytes:
Polycythemia: An excessive or abnormal
increase in the number of erythrocytes
Results from bone marrow cancer or can be a
normal physiological response to living at a high
altitude
Major problem resulting from polycythemia is
that the viscosity of blood is increased causing
it to move slowly through our systems.
Composition and Function of Blood Formed Elements
Leukocytes:
White Blood Cells (WBC’s)
Less numerous than RBC’s
Crucial to defense of the body systems against
disease
The only complete cells in blood – containing a
nucleus, nuclei and the usual organelles
Perform a protective “army” that defends
against damage from bacteria, viruses,
parasites and tumor cells
Composition and Function of Blood Formed Elements
 Leukocytes:
Unlike RBC’s which are confined to the blood only
WBC’s can move in and out of the blood vessels
through a process called diapedesis.
The circulatory system is just their way of getting to the
areas where they are needed for inflammatory or
immune responses
They move to damaged or infected areas by responding
to certain chemicals that are released when a cell is
damaged
Positive chemotaxis: the capability to respond to the
damaged cells chemical release.
Composition and Function of Blood Formed Elements
Leukocytes:
Amoeboid Motion: the formation of flowing
extensions to move them through the vessels to
the damaged area by a diffusion gradient
Once the WBC’s have reached the damaged
cell they will form around the cell and destroy it
When WBC’s are called to action the body will
produce up to twice the normal WBC’s =
Leukocytosis. If leukocytosis is read in a
persons blood draw this indicates the body is
preparing for some bacterial or viral infection.
Composition and Function of Blood Formed Elements
Leukocytes
Leukopenia: is the opposite of leukocytosis and
means that the WBC count is lower than normal. This
may be caused by certain drugs like corticosteroids
(anti-inflammatory) or cancer fighting agents.
Leukemia: meaning “white blood”. The bone marrow
becomes cancerous and produces huge numbers of
WBC’s and continually releases them into the body.
This would not normally be a problem but the newly created
WBC’s are immature and cannot carry out their normal
functions allowing the body to become “prey” for bacteria
and viruses.
Composition and Function of Blood Formed Elements
Leukocytes:
White blood cells are categorized in two ways
depending on if they contain visible granules in
their cytoplasm or not.
Granulocytes: granule containing WBC’s
• They contain lobed nuclei which are rounded nuclear
areas connected by thin strands of nuclear material
• The granules in the cytoplasm contain neutrophils,
eosinophils and basophils
Composition and Function of Blood Formed Elements
 Leukocytes:
Neutrophils →
Granulocytes:
 Neutrophils: contain multibodied nucleus and fine
granules that respond to both acid and basic
stains. The cytoplasm will stain pink and the
nucleus will stain deep purple showing the different
lobes connected by nuclear material.
• They are phagocytes at sites of acute infections
 Eosinophils: have a blue red nucleus that
resembles and old fashion phone receiver and
have large brick red cytoplasmic granules
• Their numbers increase rapidly during allergies and
infections by parasitic worms.
Composition and Function of Blood Formed Elements
Leukocytes:
Granulocytes:
Basophils: the rarest of WBC’s contain large
histamine containing granules that stain dark blue
• Histamine is a inflammatory chemical that makes blood
vessels leak and attracts other WBC’s to the infected
area.
Composition and Function of Blood Formed Elements
Leukocytes
The second type of WBC is Agranulocytes:
They lack visible cytoplasmic granules and their
nuclei are closer to normal looking
They include lymphocytes and monocytes
Lymphocytes: have large dark purple nucleus that
occupies most of the cells volume. They are slightly
larger than RBC’s and are found in the lymphatic
tissues where they play important roles in immune
response.
Composition and Function of Blood Formed Elements
 Leukocytes:
Agranulocytes:
 Monocytes: largest of the WBC’s
• They resemble larger lymphocytes except for their abundant
amounts of cytoplasm and indented nucleus.
• When they migrate to tissues they change into macrophages
with huge appetites and fight chronic infections such as
tuberculosis.
Composition and Function of Blood Formed Elements
 Platelets:
Are not cells but are fragments of bizarre multinucleate
cells called Megakaryocytes which rupture and release
thousands of anucleate pieces that seal themselves off
from surrounding fluids.
These platelets appear as dark staining irregularly
shaped bodies scattered among other blood cells
They are important for the blood clotting processes that
occurs in vessels when they are ruptured or broken.
Hematopoiesis (blood cell formation)
The formation of blood cells occurs in the
red bone marrow or Myeloid tissue which
is found mostly in the flat bones of the
adult skeleton.
Each type of blood cell is produced in
different numbers in response to changing
body needs and different stimuli.
Once they are produced and mature they
will be discharged into the blood vessels
that surround the area
Hematopoiesis (blood cell formation)
Hemocytoblast: the stem cell from which
all formed elements will come from
The development of the cells will differ and
once they are designated to a specific
body area/blood pathway they cannot
change
There are two types of stem cells which
are produced by the hemocytoblasts:
Lymphoid stem cell
Myeloid stem cell
Hematopoiesis (blood cell formation)
 Lymphoid stem cell: produces lymphocytes
 Myeloid stem cell: can produce all other classes
of formed elements
 Since RBC’s are anucleate they cannot
synthesize proteins, grow or divide so as they
age they become brittle and fragment/fall apart
in approximately 100-120 days
 Their remains will then be eliminated by
phagocytes in the spleen, liver and other body
tissues
Hematopoiesis (blood cell formation)
 The lost cells are replaced by the division of the
hemocytoblasts within the red bone marrow.
 The developing RBC’s can divide many times
and synthesize large amounts of hemoglobin
 When enough hemoglobin has been built up the
nucleus and other organelles are ejected and
the cell collapses inward becoming a young
RBC or reticulocyte because it still contains
some endoplasmic reticulum.
Hematopoiesis (blood cell formation)
Reticulocytes enter the bloodstream and
begin transporting oxygen and within 2
days of being released in the bloodstream
they will get rid of the remaining ER and
become fully functional erythrocytes
The development from a hemocytoblast to
a mature RBC takes approximately 3-5
days.
Hematopoiesis (blood cell formation)
 Erythropoietin: the hormone which controls the
production of erythrocytes.
 Normally we have small amounts of erythropoietin in our
blood circulation at all times and RBC’s are constantly
being produced.
 The liver produces some of this hormone but most of it is
made in the kidneys
 When blood levels and oxygen decline for any reason
the kidneys release their erythropoietin which targets the
red bone marrow and stimulates it to produce more
RBC’s
 If there is excessive amounts of oxygen in the blood
stream the amount of erythropoietin released will be
decreased.
Hematopoiesis (blood cell formation)
 The formation of leukocytes and platelets is also
stimulated by hormones.
 Colony Stimulating Factors (CSF’s) and
Interleukins are what prompt the red bone
marrow to turn out leukocytes and enhance the
ability of mature leukocytes to protect the body.
 Chemical signals in the body found in
inflammatory conditions also stimulate
leukocytes to be produced or be enhanced.
Hematopoiesis (blood cell formation)
Exposure to bacteria or toxins will also
stimulate macrophages and lymphocytes
to release CSF’s and interleukins which
will pull together WBC’s to fight off the
attack
Thrombopoietin: Hormone which
accelerates the production of platelets
Hemostasis
 The stopping of blood flow because of some
type of damage to the endothelium of the blood
vessel wall
 A very fast response which is localized to a
particular area
 Involves three phases that occur in a rapid
sequence:
Vascular spasms
Platelet plug formation
Coagulation
Blood clotting
Hemostasis
Steps of Hemostasis:
Platelets are repelled by an intact endothelium.
When the endothelium is broken the underlying
collagen fibers are exposed and the platelets
become “sticky” and cling to the damaged area.
These platelets will then release chemicals to
attract more platelets to the area.
As more and more platelets accumulate a small
mass called a platelet plug or white thrombus is
formed.
Hemostasis
Steps of Hemostasis:
Once anchored the platelets release serotonin
which causes the blood vessel to go into
spasms.
These spasms narrow the blood vessel at that
point, decreasing the blood flow until clotting
can occur.
At the same time the injured tissues release
thromboplastin which will play an important role
in the clotting process.
Hemostasis
 Steps of Hemostasis:
PF3: a phospholipid that coats the surfaces of the
platelets will interact with thromboplastin and calcium
ions to form an activator that triggers the “clotting
cascade”
PF3 the prothrobin activator converts prothrobin present
in plasma to thrombin – an enzyme
Once this occurs the thrombin will join soluble fibrinogen
proteins and create long hairlike molecules of insoluble
fibrin
Fibrin then forms a “mesh” trap for RBC’s to form the
basis of a blood clot.
Within an hour of this the clot will begin to react and
squeeze serum from the mass and pull the ruptured
edges of the blood vessel together.
Hemostasis
Normal blood clotting occurs within 3-6
minutes and as quickly as it is started it
can stop so that widespread clotting does
not occur – which would make the blood
hard.
Applying pressure to a wound will help to
speed up the clotting process.
Disorders of Hemostasis
Undesirable clotting:
For unknown reasons sometimes clots will form
in intact blood vessels – most commonly the
legs.
Thrombus: a clot that develops and persists in
an unbroken blood vessel
If it is large enough it may block the vessel and
prevent blood flow to the cells beyond the
blockage
Embolus: a thrombus that breaks away from the
blood vessel wall and floats freely in the blood
stream.
Disorders of Hemostasis
Undesirable clotting:
An embolus is usually not a problem unless it
gets lodged in a blood vessel that is too narrow
for it to pass through.
Possible causes of undesirable clotting may be:
Anything that roughens the endothelium of a blood
vessel and encourages clinging of platelets such as
severe burns, physical blows or an accumulation of
fatty material.
Slow flowing blood or blood pooling is a risk factor
especially in people who are unable to move
Disorders of Hemostasis
Bleeding Disorders:
The most common cause of abnormal bleeding
is platelet deficiency or thrombocytopenia =
decreased number of platelets
Thrombocytopenia: result of an insufficient
number of circulating platelets
Petechia: small purple colored blotches on the
skin that indicate small vessel breakages that
can occur with normal movement.
Usually arises from conditions where the myeloid
tissue is suppressed, bone marrow cancer, radiation
or certain drugs.
Disorders of Hemostasis
Bleeding Disorders:
When the liver cannot synthesize its usual
clotting factors severe bleeding may occur.
Vitamin K is used by the liver to produce these
clotting factors and may be deficient, causing
the severe bleeding. If so then vitamin K
supplements will solve the problem.
If liver function is severely impaired (Hepatitis,
Cirrhosis, etc.) then blood transfusions will help.
Disorders of Hemostasis
Bleeding Disorders:
Hemophilia: Hereditary bleeding disorder that
results from a lack of any of the factors that are
present during clotting.
With hemophilia a simple cut or scratch will
bleed for a prolonged period of time and could
potentially be life threatening.
If the bleeding is occurring internally in the
joints it will be painful and they could become
disabled.
Disorders of Hemostasis
Bleeding disorders:
Hemophiliacs are given transfusions of fresh
plasma or injections of the clotting factor they
are missing in order to stop the bleeding
episodes.
Because of their need for transfusions and lack
of clotting factors hemophiliacs can become
victims of AIDS and Hepatitis more easily
because they cannot defend as well against the
viruses.
Blood Groups and Transfusions
 The body can lose up to 15% of its blood without
too many problems.
 If blood loss is between 15-30% pallor (white
coloring) or weakness can occur
 Losses over 30% will cause severe shock and
can be fatal.
 Blood transfusions can be given to replace this
lost blood. For transfusions blood is collected
from a donor and mixed with an anticoagulant to
prevent clotting. This blood can then be stored
for approximately 35 days until its needed.
Blood Groups and Transfusions
Blood Groups:
People have different blood groups and if a
transfusion is given with mismatched blood it
can be fatal.
The plasma membrane of an RBC has
genetically determined proteins (Antigens) that
identify you as unique!
Because the body normally recognizes antigens
as a foreign body it will defend against it – thus
making a transfusion with the wrong blood type
fatal.
Blood Groups and Transfusions
Blood Groups:
Agglutination: the binding of the antibodies on
the surface of the antigens which will cause
RBC’s to clump together.
After agglutination occurs the foreign RBC’s will
rupture and release hemoglobin into the
bloodstream. This will cause a decrease in the
ability to carry oxygen to areas of the body.
In severe cases of mismatched transfusions the
hemoglobin molecules may block the kidney
tubules and cause kidney failure.
Blood Groups and Transfusions
Blood Groups:
Treatment to prevent kidney damage is to
infuse alkaline fluids to dilute and dissolve the
hemoglobin along with diuretics which will flush
it out of the body through urine.
There are over 30 different RBC antigens in
humans allowing each persons blood cell to be
classified into different blood groups.
The antigens of the ABO and Rh blood groups
cause the most vigorous transfusion reactions.
Blood Groups and Transfusions
 Blood Groups:
ABO blood groups: based on which of two antigens,
type A or type B, you inherit.
Absence of both of these antigens results in a type O
blood.
Presence of both will lead to type AB
If you only have antigen A you will have type A blood
and if only antigen B is present you will have type B
blood.
You will build up antibodies to antigen A or antigen B
depending on which you are missing.
Blood Groups and Transfusions
Rh Blood groups:
Named because one of the Rh antigens
(antigen D) was originally found in rhesus
monkeys then later found in humans.
Most Americans are Rh positive which means
we carry the Rh antigen in our RBC’s.
Anti-Rh antibodies are not automatically formed
and present in the blood of Rh- individuals
If an Rh- receives Rh+ blood shortly after the
transfusion their immune system becomes
sensitized and will produce antibodies against
the foreign blood type.
Blood Groups and Transfusions
 Rh Blood Groups:
Hemolysis: rupture of the RBC’s that creates antigens
will not occur with the first transfusion because it takes
time for the body to react and begin its antibody
production. Every time after the first the body will react
to the transfusion and attack and rupture the donated
RBC’s
An important reaction occurs when Rh- women are
carrying Rh+ babies. The first child born will be healthy
but because the mother is sensitized by the Rh+ antigen
that have passed through the placenta to her
bloodstream she will form Rh+ antibodies unless she
gets treated with RhoGAM shortly after giving birth.
RhoGAM is an immune serum that prevents the
sensitization and decreases her immune response to
the Rh+
Blood Groups and Transfusions
Rh Blood Groups:
Hemolytic disease of the newborn: if the mother
is not treated with the RhoGAM then with her
next pregnancy her body will send out the Rh+
antibodies and destroy the babies RBC’s. The
baby will be anemic and become hypoxic (lack
of oxygen). Brain damage and death could
occur if fetal transfusions are not done before
birth to provide more RBC’s to transport
oxygen.
Blood Groups and Transfusions
Blood typing:
In order to make sure that an accurate and safe
transfusion is made both the recipient and
donor’s blood type must be determined.
To determine blood type a blood draw is taken
and mixed with two different types of immune
serum – anti-A and anti-B
Agglutination will occur when the RBC’s of a
group A person are mixed with the anti-A serum
and likewise when group B is mixed with anti-B
Blood Typing
Go to the link below and read the statement
on blood typing and do the activity linked
with it.
http://nobelprize.org/medicine/educational/la
ndsteiner/readmore.html
Developmental Aspects of Blood