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Human Anatomy,
First Edition
McKinley & O'Loughlin
Chapter 21:
Blood
1
Blood

Considered a connective tissue: contains
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Cells
a liquid ground substance (called plasma)
dissolved protein fibers.
About four times more viscous (or thicker)
than water.
Temperature of blood is about 1°C higher
than measured body temperature.
21-2
Blood

Whole blood can be separated:
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Liquid component
cellular components
machine called a centrifuge.
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blood is withdrawn from a vein and collected in a
centrifuge tube
tube is placed into the centrifuge, which then
spins it in a circular motion for several minutes
rotational movement separates the blood into
liquid and cellular components
21-3
4
Components of Blood
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Erythrocytes (or red blood cells)
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Buffy coat
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form the lower layer of the centrifuged blood
typically make up about 44% of a blood sample
makes up the middle layer
thin, slightly gray-white layer composed of cells called
leukocytes (or white blood cells) and cell fragments called
platelets
forms less than 1% of a blood sample
Plasma

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straw-colored liquid that rises to the top
generally makes up about 55% of blood
21-5
Components of Blood
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Erythrocytes and the components of the buffy coat
are called the formed elements.
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not “cells,” merely fragments broken off from a larger cell
Formed elements and the liquid plasma compose
whole blood.
21-6
7
Functions of Blood –
Transportation

Transports numerous elements and compounds
throughout the body.
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erythrocytes carry oxygen from the lungs to body cells and
then transport carbon dioxide from the cells back to the
lungs for expulsion from the body
blood plasma
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transports nutrients that have been absorbed from the GI tract
hormones secreted by the endocrine organs to their target cells
plasma
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carries waste products from the cells to organs such as the
kidneys, where these waste products are removed
21-8
Functions of Blood –
Regulation of Body Temp.

Regulates body temperature.
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plasma absorbs and distributes heat throughout
the body
for cooling the blood vessels in the dermis dilate
and dissipate the excess heat through the
integument
when the body needs to conserve heat, the
dermal blood vessels constrict, and the warm
blood is shunted to deeper blood vessels in the
body
21-9
Functions of Blood –
Regulation of pH Levels

pH is a measure of how alkaline or acidic a fluid is.
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Neutral pH is measured at exactly 7.
Acidic fluids (e.g., orange juice) are between 0 and 7.
Alkaline fluids (e.g., milk) are between 7 and 14.
Blood plasma contains compounds and ions that may
be distributed to the fluid among tissues (interstitial
fluid) to help maintain normal tissue pH.
Blood plasma pH is continuously regulated at a value
of 7.4 the pH level required for normal cellular
functioning.
21-10
Functions of Blood –
Maintenance of Fluid Levels
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Maintains normal fluid levels in the cardiovascular
system.
Prevents fluid loss.
Constant exchange of fluid between the blood plasma
and the interstitial fluid.
If too much fluid is absorbed in the blood, high blood
pressure results.
If too much fluid escapes the bloodstream and enters
the tissues, blood pressure drops to unhealthy low
levels, and the tissues swell with excess fluid.
21-11
Functions of Blood –
Maintenance of Fluid Levels

To maintain balance of fluid exchange between the
blood and the interstitial fluid, blood contains
compounds (such as salts and some proteins) to
prevent excess fluid loss in the plasma.
21-12
Functions of Blood –
Protection
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Leukocytes (white blood cells) help guard against
infection by mounting an immune response if a
pathogen or an antigen is found.
Plasma transports antibodies, which are molecules
that can immobilize antigens until a leukocyte can
completely kill or remove the antigen.
Platelets and blood proteins protect the body against
blood loss by forming blood clots on damaged
vessels.
21-13
Components of Plasma
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Complex mixture of water, proteins, and other
solutes.
When the proteins are moved from plasma, the
remaining fluid is termed serum.
Water makes up about 92% of plasma’s total volume.

water facilitates the transport of materials in the plasma
21-14
Plasma Proteins
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The next most abundant materials in plasma
are the plasma proteins.
Make up about 7% of the plasma.
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6 and 8 grams of protein in a volume of 100
milliliters of blood (referred to as g/dl)
The plasma proteins include:
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albumins
globulins
fibrinogen
regulatory proteins
21-15
Plasma Proteins – Albumins
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Smallest and most abundant of the plasma proteins.
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make up approximately 58% of total plasma proteins
Regulate water movement between the blood and
interstitial fluid.
Albumins act as transport proteins that carry ions,
hormones, and some lipids in the blood.
21-16
Plasma Proteins – Globulins
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Second largest group of plasma proteins, forming
about 37% of all plasma proteins.
Smaller alpha-globulins and the larger beta-globulins
primarily bind, support, and protect certain waterinsoluble or hydrophobic molecules, hormones, and
ions.
Gamma-globulins: Also called immunoglobulins or
antibodies.
Produced by some of our defense cells to protect the
body against pathogens that may cause disease.
21-17
Plasma Proteins – Fibrinogen
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Makes up about 4% of all plasma proteins.
Responsible for blood clot formation.
Following trauma to the walls of blood vessels,
fibrinogen is converted into long, insoluble strands of
fibrin, which is the essence of a blood clot.
21-18
Plasma Proteins – Regulatory
Proteins
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Form a very minor class of plasma proteins.
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<1% of total plasma proteins
Include enzymes to accelerate chemical reactions in
the blood and hormones being transported
throughout the body to target cells.
21-19
Solutes
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Plasma is an extracellular fluid (ECF).
 it includes all body fluids that are not found inside
cells
Plasma is somewhat like interstitial fluid, in that
 both have similar concentrations of nutrients,
waste products, and electrolytes
Concentration of dissolved oxygen is higher in plasma
than in interstitial fluid, because the cells take up and
use the oxygen from the interstitial fluid during
energy production.
21-20
Solutes
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Difference in concentration ensures that
oxygen will continue to diffuse from the
blood into the tissues.
Difference in concentration ensures that
carbon dioxide will readily diffuse from
the interstitial fluid into the blood,
where it will be carried to the lungs and
discharged from the body.
21-21
Formed Elements in the Blood
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Erythrocytes
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Leukocytes
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make up more than 99% of formed elements
primary function is to transport respiratory gases in the
blood
make up less than .01% of formed elements
contribute to defending the body against pathogens
Platelets
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make up less than 1% of formed elements and
help with blood clotting
21-22
Hematocrit
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Percentage of erythrocytes in the blood.
Values vary slightly and are dependent on age and sex.
Adult males range between 42% and 56% .
Females range from 38% to 46%.
Childrens’ hematocrit ranges also vary and differ from adult
values.
Altitude can affect the hematocrit.
 body compensates by making more erythrocytes
 more erythrocytes in the blood can carry more oxygen to the
tissues
21-23
24
Erythrocytes
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Mature erythrocytes lack nuclei.
Transport oxygen and carbon dioxide to and from the
tissues and the lungs.
Lack of nuclei enables them to carry respiratory
gases more efficiently.
21-25
26
Hemoglobin in Erythrocytes
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Every erythrocyte is filled with approximately 280
million molecules of a red-pigmented protein called
hemoglobin.
Transports oxygen and carbon dioxide, and is
responsible for the characteristic bright red color of
arterial blood.
Hemoglobin that contains no oxygen has a deep red
color that is perceived as blue because the blood
within these veins is observed through the layers of
the skin and the subcutaneous tissue.
21-27
Hemoglobin in Erythrocytes
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Each hemoglobin molecule consists of four protein building
blocks, called globins.
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All globin chains contain a nonprotein (or heme) group:
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Alpha (a) chains
Beta (b) chains.
ring shaped
an iron (Fe) ion in its center.
Oxygen binds to these iron ions for transport in the blood.
Each hemoglobin molecule:
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four iron ions
is capable of binding four molecules of oxygen.
21-28
Hemoglobin in Erythrocytes
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Oxygen binding is fairly weak
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Oxygen binds to the hemoglobin
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ensures rapid attachment and detachment of oxygen with
hemoglobin.
when the erythrocytes pass through the blood vessels of the lungs.
It leaves the hemoglobin
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when the erythrocytes pass through the blood vessels of body
tissues.
21-29
30
Erythrocyte Life Cycle
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No organelles, therefore can not sustain itself.
Finite life span of about 120 days.
Daily:
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Are phagocytized by liver and spleen.
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About 1% of oldest RBCs are removed
By macrophages
Some components saved, some discarded
21-31
32
Erythrocyte Life Cycle
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Some components saved, some discarded
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Heme group:
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Converted to biliverdin (green pigment)
Then converted to bilirubin
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In bile, produced by liver
Bile enters the digestive tract
 Helps emulsify fat
 Bilirubin modified and removed via urine and feces
Iron:
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Transported by transferrin to liver
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Transferred to ferritin for storage
Ferritin can be transported to red bone marrow
21-33
Blood Types
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Determined by membrane proteins in the RBC cell
membrane.
Called surface antigens (agglutinogens).
Most common group: ABO blood group
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Two antigens: A and B
ABO blood types:
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Type A: have the A surface antigen
Type B: have the B surface antigen
Type AB: have both the A and the B surface antigens
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Type O: have neither the A or the B surface antigen.
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21-34
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Blood Types
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Antibodies (agglutinins) to the surface
antigens are in the plasma
ABO group has anti-A antibodies and
anti-B antibodies
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Type
Type
Type
Type
A: have anti-B
B: have anti-A
AB: has neither anti-A or anti-B
O: has both anti-A and anti- B
21-36
Antibodies
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An antibody interacts with a specific antigen.
The ABO blood group has both anti-A and anti-B
antibodies that react with the surface antigen A and
the surface antigen B, respectively.
The antibodies in your blood plasma do not recognize
the surface antigens on your erythrocytes.
21-37
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Blood Types
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Rh blood type
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Based on another surface antigen
Called either Rh or D
Rh positive (Rh+): has the antigen
Rh negative (Rh-): does not have the
antigen
21-40
Blood Types
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Rh blood type
Antibody only present with exposure to Rh+
blood (the antigen)
Only people with Rh- blood can have the
antibody
Erthryroblastosis fetalis: Rh+ antibodies in
plasma of an Rh- mother can cross the
placenta
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RhoGAM: prevent antibody development
21-41
Leukocytes
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Leukocytes help initiate an immune response and
defend the body against invading pathogens.
Leukocytes are true “cells” in that they contain a
nucleus and cellular organelles.
Leukocytes also differ from erythrocytes in that they
are about 1.5 to 3 times larger, and they do not
contain hemoglobin.
21-42
21-43
Leukocytes
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The five types of leukocytes are divided into two
distinguishable classes—granulocytes and
agranulocytes—based upon the presence or absence
of visible organelles termed specific granules.
21-44
Leukocytes – Granulocytes
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Neutrophil
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Eosinophils have reddish, or pink-orange granules in their
cytoplasm.
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60–70% of the total number of leukocytes
constitute about 2–4% of the total number of leukocytes
nucleus usually has two lobes, which are connected by a thin
strand
Basophils are
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1.5 times larger than erythrocytes
least numerous of the granulocytes
constitute about 0.5–1% of the total number of leukocytes
always exhibit a bilobed nucleus and abundant blue-violet granules
in the cytoplasm
21-45
21-46
Leukocytes – Agranulocytes
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Agranulocytes are leukocytes that have such small
granules in their cytoplasm that they are frequently
overlooked upon casual observation—hence the
name agranulocyte.
Agranulocytes include both lymphocytes and
monocytes.
21-47
21-48
Leukocytes – Agranulocytes Lymphocytes
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T-lymphocytes (T-cells)
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B-lymphocytes (B-cells)
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manage and direct an immune response
some directly attack foreign cells and virusinfected cells
stimulated to become plasma cells and produce
antibodies
Natural killer cells (NK cells)
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attack abnormal and infected tissue cells
21-49
21-50
Leukocytes – Agranulocytes Monocytes
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Up to three times the diameter of an erythrocyte.
Constitute about 3–8% of all leukocytes.
Nucleus is kidney-shaped or U-shaped.
Macrophages phagocytize bacteria, cell fragments,
dead cells, and debris.
21-51
Platelets
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Irregular, membrane-enclosed cellular
fragments
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about 2 micrometers in diameter (less than onefourth the size of an erythrocyte).
In stained preparations, they exhibit a dark
central region.
Sometimes called thrombocytes.
Continually produced in the red bone
marrow by cells called megakaryocytes.
21-52
21-53
Platelets
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Severe trauma to a blood vessel causes
the blood to coagulate, or clot.
Components in the plasma produce a
web of fibrin that traps erythrocytes
and platelets in the web to halt blood
flow.
21-54
Hemopoiesis
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Also called hematopoiesis
Production of the formed elements of
blood
Occurs in red bone marrow
21-55
Hemopoiesis
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Begins with hemopoietc stem cells
Called Hemocytoblast
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Pluripotent cells
Produce two cell lines
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Myloid line
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Everything but lymphocytes
Lymphoid line
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lymphocytes
21-56
21-57
Hemopoiesis
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Influenced by a number of hormones and
growth factors
Colony-stimulating factors:
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Multi-CSF: RBCs,granulocytes,monocytes, platelets
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GM-CSF: granulocytes, monocytes
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From myloid stem cell
From progenitor cell
G-CSF: granulocytes
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From myeloblast cells
21-58
Hemopoiesis
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Colony-stimulating factors: contined
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M-CSF: monocytes
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From monoblasts
Thrombopoietin: megakaryocytes and
platelets
Erythropoietin: hormone from the kidney,
RBC’s
21-59
Hemopoiesis
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Erythropoiesis: from progenitor cell
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Reticulocyte: loses all organelles
Thrombopoiesis
Leukopoiesis
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Granulocyte maturation: from myeloblast
Monocyte maturation: from monoblast
Lymphocyte maturation: from lymphoid stem cell
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B-lymphoblast
T-lymphoblast
21-60
21-61