Cardiovascular System: The Blood
Dr. Michael P. Gillespie
Constituents Of Blood
 Blood is a connective tissue composed of a
liquid matrix called plasma that dissolves
and suspends various cells and fragments.
 Interstitial fluid is the fluid that bathes body
cells.
Functions of Blood
 Transportation – oxygen, carbon dioxide,
nutrients, hormones, heat, & waste products.
 Regulation – maintains homeostasis (ph,
heat, osmotic pressure).
 Protection – clotting, WBCs, & antibodies.
Physical Characteristics Of
Blood
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Blood is denser and more viscous than water.
The temperature is 38 degrees C (100.4 degrees F).
Slightly alkaline ph ranging from 7.35 to 7.45.
20% of the extracellular fluid (about 8% of total
body mass).
 The blood volume is 5 to 6 liters (1.5 gal) in an
average adult male and 4 to 5 liters (1.2 gal) in an
average adult female.
Withdrawing Blood
 Blood samples for laboratory testing are obtained in
various ways.
 Venipuncture (the most common method).
 A finger or heel stick is utilized for children and
people who must monitor their blood daily (I.E.
Diabetics).
 An arterial stick is utilized when the level of O2
must be determined.
Components Of Blood
 Whole blood has two components:
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Blood plasma, a watery liquid matrix that
contains dissolved substances.
Formed elements (cells and cell fragments).
 45% formed elements and 55% plasma.
Blood Plasma
 A straw-colored liquid which is about 91.5% water
and 8.5% solutes.
 Plasma proteins – maintain osmotic pressure.
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Albumins, globulins, and fibrinogen (synthesized by
hepatocytes).
Gamma globulins (antibodies 0r immunoglobulins).
 Electrolytes, nutrients, regulatory substances (i.E.
Enzymes and hormones), gases, & waste products
(urea, uric acid, creatinine, ammonia, and bilirubin).
Formed Elements
 RBCs.
 WBCs – perform many functions.
Formed Elements
 Platelets – cell fragments.
Formed Elements
 Hematocrit – the percentage of total blood occupied
by RBCs.
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Males have a higher hematocrit than females because
testosterone stimulates the production of erythropoeitin
(EPO).
Menstruation leads to lower values for females during
their reproductive years.
Anemia is a significant drop in the hematocrit.
Polycythemia is an.
Abnormally high percentage of RBCs.
Causes of Polycythemia
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Abnormal increase in RBC production.
Tissue hypoxia.
Dehydration.
Blood doping or use of Epoetin alfa (Procrit or
Epogen) by athletes.
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This increases the work load of the heart.
The increased #s of RBCs raise the viscosity of the
blood, which increases the resistance to blood flow. This
can cause high blood pressure and stroke.
Formation of Blood Cells
 Hemopoiesis (hematopoiesis) – the process by
which the formed elements of blood develop.
 Blood cells, macrophages, reticular cells, mast cells,
and adipocytes arise from the red bone marrow.
 Pluripotent stem cells in the bone marrow
reproduce themselves, proliferate and differentiate
into mature blood cells.
Two Types of Pluripotent Stem
Cells
 Myeloid stem cells.
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Give rise to red blood cells, platelets, monocytes,
neutrophils, eosinophils, and basophils.
 Lymphoid stem cells.
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Give rise to lymphocytes.
Generations Of Cell Lines In
The Development Of Blood
Cells
 Pluripotent stem cells – mesenchymal cells
which have the capacity to develop into
many different types of cells. They can
reproduce themselves.
 Progenitor cells – cannot reproduce
themselves.
 Precursor cells (blasts) – they develop into
the actual formed elements of the blood.
Hormones That Regulate Blood
Cell Development
 Hemopoietic growth factors – regulates
differentiation and growth of progenitor cells.
 Erythropoietin (EPO) from the kidneys – increases
the # of RBC precursors.
 Thrombopoietin (TPO) from the liver – stimulates
the formation of platelets.
 Colony-stimulating factors (CSFs) or interleukins
stimulate WBC formation.
Medical Uses of Hemopoietic
Growth Factors
 EPO is utilized in end stage kidney disease to
increase RBC formation.
 CSFs are utilized to stimulate WBC
formation in cancer patients undergoing
chemotherapy.
 Thrombopoietin helps induce platelet
formation in chemotherapy patients.
Red Blood Cells
 Red blood cells (RBCs) or erythrocytes:
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Contain hemoglobin – oxygen-carrying protein
which gives the cell its color.
Approximately 5 million RBCs are present per
microliter of blood.
Approximately 2 million RBCs are created and
destroyed per second.
RBC Anatomy
 Biconcave discs with a diameter of 7-8
micrometers.
 The plasma membrane is flexible, which allows
them to deform without rupturing as they squeeze
through capillaries.
 RBCs lack a nucleus and other organelles.
 RBCs cannot reproduce or carry on extensive
metabolic activities.
RBC Physiology
 With no nucleus, RBCs have more space
available for oxygen transport.
 RBCs lack mitochondria and generate ATP
anaerobically; Consequently, they do not use
up the oxygen they are transporting.
RBC Physiology
 The biconcave disc has a greater surface area
allowing greater diffusion of gas molecules.
 Hemoglobin binds to oxygen, carbon
dioxide, and nitric oxide (NO).
 NO causes vasodilation which enhances
oxygen delivery to cells.
RBC Life Cycle
 Red blood cells live only about 120 days.
 Macrophages in the spleen and liver remove dead
RBCs through phagocytosis.
 Hemoglobin is broken down into its globin and
heme portions.
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Globin is broken down into amino acids, which are
reused for proteins.
Heme is converted into the yellow-orange pigment
bilirubin.
Reticulocyte Count
 The rate of eryhtropoiesis is measured by a
reticulocyte count.
 Low “retic” count – could indicate a shortage
of erythropoietin due to a nutritional
deficiency or leukemia.
 High “retic” count – could indicate a good
response to previous blood loss, iron therapy,
or illegal use of Epoetin by an athlete.
White Blood Cells
 White blood cells (WBCs) or leukocytes
have a nucleus and do not contain
hemoglobin.
 Classified as either granular or agranular.
Types Of White Blood Cells
 Eosinophil
 Basophil
 Neutrophil
 Small lymphocyte
 Monocyte
Numbers Of WBCs
 RBCs outnumber WBCs by about 700:1.
 There are approximately 5000 – 10,000 cells per
microliter of blood.
 Leukocytosis – an increase in the number of WBCs
due to stresses such as microbes, strenuous
exercise, anesthesia, or surgery.
 Leukopenia – a decrease in the number of WBCs
due to radiation, shock, or chemotherapy.
Functions Of WBCs
 The WBCs combat pathogens by
phagocytosis and other immune responses.
 WBCs leave the bloodstream by emigration.
Functions Of WBCs
 Neutrophils and macrophages are active in
phagocytosis.
 Phagocytes are attracted to inflamed tissues
through a process called chemotaxis.
 Phagocytes release the enzyme lysozyme,
which destroys certain bacteria.
Functions Of WBCs
 Eosinophil – release histamines. Respond to
allergic responses and parasitic infection.
 Basophil – liberate heparin, histamine, and
serotonin. They intensify the inflammatory
reaction and are involved in hypersensitivity
(allergic) reactions.
Functions Of WBCs
 Neutrophil – active in phagocytosis and
ingest bacteria and dead matter. They
respond to bacteria and fungi.
 Lymphocyte – “soldiers” of the immune
system.
 Monocyte – turn into macrophages and clean
up cellular debris after an infection.
Differential WBC Count
 Utilized to detect infection, inflammation,
poisoning, blood disorders, effects of
chemotherapy, allergic reactions, and
parasitic infections.
Significance Of High & Low
WBC Counts
WBC Type
High Count
Low Count
Neutrophils
Bacterial
infection, burns,
stress,
inflammation
Viral infection,
leukemia
Radiation, drug
toxicity, B12
deficiency, SLE
Lymphocytes
Prolonged
illness,
immunosuppress
ion, cortisol tx.
Significance Of High & Low
WBC Counts
Monocytes
Eosinophils
Basophils
Viral or fungal
infection,
chronic diseases
Allergic rx.,
parasites,
autoimmune dis.
Allergic rx.,
cancers,
hypothyroidism
Bone marrow
suppression,
cortisol tx.
Drug toxicity,
stress
Pregnancy,
ovulation, stress,
hyperthyroidism
Platelets
 The hormone thrombopoietin influences the
production of platelets (thrombocytes).
 Platelets help stop blood loss by forming a
platelet plug.
Complete Blood Count (CBC)
 A test that screens for anemia and various
infections.
 Counts of RBCs, WBCs, platelets,
hematocrit, and a differential white blood
cell count are included.
Blood Clotting
 Serum is a straw colored liquid and the gel is
called a clot.
 The process of gel formation is called
clotting or coagulation.
 Clotting factors are involved in the
coagulation cascade.
Blood Clotting
 Normal clotting requires vitamin K, which is
produced by bacteria in the intestines.
 Dissolution of a clot is called fibrinolysis.
 Anticoagulants (heparin & Warfaring a.K.A.
Coumadin) are utilized for patients at risk of
forming a blood clot.
Intravascular Clotting
 Thrombosis – clotting in an unbroken blood vessel.
 Thrombus – the clot itself.
 Embolus – a blood clot, bubble of air, fat from
broken bones, or a piece of debris transported by
the bloodstream.
 Pulmonary embolism – when an embolus lodges in
the lungs.
ABO Blood Group
 Type A blood - RBCs display only antigen A.
 Type B blood – RBCs display only antigen B.
 Type AB blood – RBCs display both antigens A &
B.
 Type O blood – RBCs display neither antigen A or
B.
ABO Blood Group
 The blood plasma contains isoantibodies or
agglutinins that react with A or B antigens if
mixed.
 You do not have the antibodies that react
with the antigens of your own RBC type, but
you most likely have the antibodies for
antigens your own blood lacks.
Rh Blood Group
 People with Rh antigens in their blood are Rh
positive and people without the Rh antigen
are Rh negative.
 Normally, plasma does not contain anti-Rh
antibodies.
Rh Blood Group
 If an Rh- person receives Rh+ blood
transfusion, he or she will start to make
antibodies that will remain in the blood.
 The next time he or she receives Rh+ blood,
the antibodies will cause hemolysis of the
donated blood.
Hemolytic Disease Of The
Newborn
ABO Blood Group Interactions
Characteristics
A
B
AB
O
Antibody Anti-B
in plasma
Antigen on A
RBCs
Anti-A
Neither
Both
B
A&B
Neither
Donors
B, O
A, B,
AB, O
None
O
A, O
Hemolysis B, AB
A, AB
A, B, AB