BLOOD
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I. Functions of Blood
A. There are five functions of the blood
1. The transport of dissolved gases,
nutrients, hormones, and metabolic wastes.
2. The regulation of the pH and
electrolyte composition of interstitial
fluids throughout the body.
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3. The restriction of fluid losses through
damage vessels or at other injury
sites/blood clotting.
4. Defense against toxins and pathogens.
5. The stabilization of body temperature.
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B. The composition of
Blood
1. Blood contains plasma and formed
elements.
2. Plasma contains dissolved proteins.
Because these proteins are in solutions,
plasma is slightly denser than water.
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3. Formed elements are blood cells (red or
white) and cell fragments (cell platelets) that
are suspended in the plasma.
4. Red blood cells (RBC’s) or erythrocytes
transport oxygen and carbon dioxide.
5. The less numerous white blood cells
(WBC’s) or leukocytes are cells involved with
body’s defense mechanisms.
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6. Platelets are pieces of cytoplasm that
contain enzymes and are important to blood
clotting.
7. Together the plasma and formed elements
constitute whole blood.
8. The volume of blood varies from 5-6 liters in
the cardiovascular system of an adult man and
from 4-5 liters in an adult woman.
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9. BUT, when a woman is pregnant she
can have up to an extra liter of blood.
10. Whole blood components may be
separated, or fractionated.
11. Whole blood contains 55% plasma
and 45% formed elements.
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12. The plasma composition is:
Plasma proteins 7%
other solutes 1%
Water
92%
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13. The formed elements compositions
is:
Platelets and WBC’s
Red blood cells
.1%
99.9%
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C. Plasma
1. Plasma contains lots of dissolved
proteins.
2. Albumins make up 60% of the
proteins. Albumins contribute to osmotic
concentration of plasma, transports lipids
and steroid hormones.
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3. Globulins make up 35% of the
proteins in plasma. Globulins transport
ions, hormones, and lipids and also have
immune functions.
4. Antibodies are also called
immunoglobulins
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5. Fibrinogen makes up 4% of the
proteins in plasma. Fibrinogen is
essential component of clotting.
6. The fluid left after the clotting proteins
are removed is known as serum.
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7. The liver makes more than 90% of the
plasma proteins, including all the albumins,
fibrinogen and most of the globulins.
8. Because the liver is the primary source of
plasma proteins, liver disorders can alter the
composition and functional properties of the
blood.
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II. Formed Elements
A. The major types of cells in blood are
RBC, WBC and platelets.
B. The production of formed elements
1. The process of hemopoesis
produces formed elements.
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2. Embryonic blood cells appear in the
bloodstream during the third week of
development.
3. These embryonic cells differentiate into stem
cells.
4. Stem cells are cells that haven’t
differentiated into a particular cell. See page
358.
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C. Red Blood Cells
1. RBC’s contain the pigment
hemoglobin, which binds and transports
oxygen and carbon dioxide. RBC’s are
the most abundant blood cells.
2. A single drop of blood contains some
260 million RBC’s.
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3. RBC’s are specialized to transport oxygen
and carbon dioxide within the bloodstream.
4. The unusual shape of a RBC has two
important reasons 1- it gives each RBC a large
surface area to increase diffusion and 2- it
enables RBC’s to bend, flex and squeeze
through capillaries.
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5. An RBC is exposed to severe physical
stresses. A single round trip of the circulatory
system usually takes less than 1 minute.
6. Because of all this stress a single RBC’s has
a life of about 120 days.
7. You are making about 3 million new RBC’s
EACH second!
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8. Red blood cell formation or
erythropoesis occurs in red bone marrow.
9. Red bone marrow or myeloid tissue is
located in the vertebrae, sternum, ribs,
scapulae, pelvis and proximal limb bones.
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10. Other marrow areas contain a fatty
tissue known as yellow bone marrow.
11. Under extreme stimulation, such as
blood loss areas of yellow marrow can
convert to red marrow, increasing the
rate of RBC formation.
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III. RBC’s and blood Types
A. Antigens are substances that can
trigger an immune response, a defense
mechanism that protects you from
infection.
1. Cell membranes contain surface
antigens, substances that the body’s
immune defenses recognize as “normal.”
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2. A person’s blood type is determined by the
presence or absence of specific antigens in the
blood.
3. The surface antigens of RBC’s are often
called agglutinogens.
4. Three particular important antigens are A, B
and Rh.
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Blood types
Antigens
Antibodies
A
B
AB
O
RH+
RH-
A
B
A B
--+
------
B
A
--A, B
---+
-
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5. See chart page 352 to view break
down of blood types.
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Antibodies and cross-reactions
1. Blood type is checked before an individual
gives or receives blood. If someone is given
the wrong blood type he/she will die.
2. Plasma contains antibodies, or agglutinins that
will attack the surface antigens on foreign cells.
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3. When an antibody meets its specific antigen,
a cross reaction occurs. Initially the RBC’s
clump together this is called agglutination.
They may also break up or hemolyze.
4. Clumps and fragments of RBC’s under
attack form drifting masses that can plug small
vessels in the kidneys, lungs, heart, or brain.
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5.
To avoid this the donor and the
recipient must be compatible in blood
type and Rh factor.
6. Rh- has no antigens BUT it has
antibodies against Rh+
Rh+ has + antigens BUT NO antibodies.
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6. IF a women was Rh- and her unborn
child was Rh+ there is a possibilities that
her body will attack the unborn child
because the child is + and destroy the
child. This usually does not happen with
the first child.
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C. White Blood Cells
1. White blood cells, also known as
leukocytes can be distinguished from
RBC’s because each has a nucleus and
does not have hemoglobin.
2. WBC’s help defend the body from
pathogens and remove toxins, wastes and
abnormal or damaged cells.
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3. WBC’s are divided
into two groups on
the basis of their
appearance after
staining 1granulocytes (lots of
granules) 2agranulocytes (not
many if any granules)
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D. WBC circulation and
movement
1. WBC’s do not circulate for extended
periods.
2. WBC’s are sensitive to chemicals,
radiation.
3. Circulating WBC’s have four
characteristics:
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a. Have amoeboid movement.
B b. Migrate out of the bloodstream.
c. Attracted to specific chemical stimuli, they
are called positive chemotaxis.
d. Neutrophils, eosinophils and monocytes are
capable of phagocytosis.
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E. General Functions
1. Neutrophils, eosinophils, basophiles
and monocytes contribute to the body’s
nonspecific defenses of the immune
system.
2. Lymphocytes are the cells responsible
for specific immunity.
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3. 50-70% of the circulating WBC’s are
Neutrophils. They are usually the first of
the WBC’s to arrive at an injury site.
They are very active phagocytes, and
specialize in attacking and destroying
bacteria. They have a short life span of
only 10 hours
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4. 2-4% of WBC’s are eosinophils and
are similar to Neutrophils. But they
generally ignore bacteria and cellular
debris. They are attracted instead to
foreign compounds that have reacted
with circulating antibodies. They increase
during an allergic reaction or a parasitic
worm infection.
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5. Less than 1% of WBC’s are basophiles.
They migrate to sites of injury and cross the
capillary wall to accumulate within the damaged
tissue. They prevent blood clotting.
6. 2-8% of WBC’s are monocytes and they are
about 2 the size of a RBC. They stay in the
circulatory system for about 24 hours before
entering the peripheral tissue.
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7. 20-30% of WBC’s are lymphocytes
and they are about the same size of a
RBC. They continuously migrate from the
bloodstream to the peripheral tissue and
back. They protect the body and its
tissues. They attack both foreign cells
and abnormal cells of the body and
secrete antibodies into the circulation.
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F. The differential count and
changes in WBC profiles
1. The normal range for each cell is on
page 357.
2. Certain disorders or diseases will be
discovered examining the blood.
3. Leukopenia indicates inadequate
numbers of WBC’s.
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4. Leukocytosis refers to excess numbers
of WBC’s.
5. Leukemia is cancer of blood forming
tissues.
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