Key Questions for
Understanding the Blood
What substances does blood
transport through blood vessels?
 Nutrients
 Wastes
 Body heat
2. Blood is the only fluid body
tissue.
What are formed elements? What
is plasma?
 Formed elements are living cells
 Plasma is a nonliving fluid matrix
What are erythrocytes?
 Erythrocytes are red blood cells that
function in oxygen transport
What is the buffy coat? What are
leukocytes? What are platelets?
 The buffy coat is a thin, whitish layer
formed at the junction of formed
elements and plasma
 Leukocytes are white blood cells that
act in various ways to protect the
body
 Platelets are cell fragments that
function in the clotting process
Percentages of Blood Volume by
components:
Plasma: 55%
Red Blood Cells: 44.2%
Leukocytes and Platelets: <1%
What are plasma proteins? Where
are they made?
 Plasma proteins are the most
abundant solutes in plasma. They are
made in the liver.
How do red blood cells differ from
other blood cells?
 Red blood cells are anucleate; that is,
they do not have a nucleus
What is hemoglobin?
 Hemoglobin is an iron-containing
protein that transports most of the
oxygen carried in the blood.
How many molecules of O2 can
each RBC carry?
 Each RBC can carry 1 billion
molecules of oxygen
 12-18 grams of hemoglobin are found
in each 100 mL of blood
What is anemia? What 2 conditions
can cause anemia?
 Anemia is a decrease in the oxygencarrying ability of the blood.
 Anemia is caused by lower than
normal numbers of RBC’s or abnormal
or deficient hemoglobin content
Who usually suffers from sickle-cell
anemia? Why?
 Black people who live in the malaria
belt of Africa, and their descendents,
usually suffer from sickle-cell anemia.
 The same gene that causes sickling
makes red blood cells infected with
malaria die and prevents them from
multiplying
What is polycthemia?
 Polycthemia is an excessive or
abnormal increase in the number of
erythrocytes caused by bone marrow
cancer or living at high altitudes
 This is a problem because of
increased blood viscosity
What is diapedesis?
 Diapedesis is the ability to slip into
and out of the blood vessels from
cells of the body.
Describe leukocytosis.
 Leukocytosis is a total WBC count
above 11,000 cells per cubic
millimeter, which indicates that a
bacterial or viral infection is beginning
in the body
What are the causes and symptoms
of leukemia?
 When bone marrow becomes
cancerous and huge numbers of
WBC’s are “turned out” rapidly, the
body becomes sensitive to bacteria
and viruses because the WBC’s are
incapable of normal activities.
Differentiate between the 2 major
groups of white blood cells
Granulocytes
Agranulocytes
1. neutrophils: phagocytes at 1. lymphocytes: stay in
sites of acute infection
lymphatic tissue, play a role
in the immune response
2. eosinophils: # increases
during allergies and
infections by parasitic worms
3. basophils: contains
histamine, which attracts
other WBC’s to the
inflammatory site
2. monocytes: become
macrophages that fight
chronic infections
Where does hematopoiesis occur?
 Hematopoiesis occurs in the myeloid
tissue of red bone marrow
 In adults, it occurs in the flat bones of
the skeleton and the proximal
epiphyses of the humerus and femur
What are hemocytoblasts?
 Hemocytoblasts are stem cells that
reside in red bone marrow, which can
develop into any of the formed
elements
Definition of Hemostasis:
 Hemostasis is the stoppage of blood
flow
3 phases of hemostasis:
1. Platelet plug forms: platelets stick to
broken blood vessels
2. Vascular spasms occur: spasms
narrow the blood vessel, decreasing
blood loss
3. Coagulation occurs: enzymes are
released to activate clotting
How long does clotting normally
take?
 3 to 6 minutes
2 Steps that speed up the clotting
process:
1. Placing a sterile gauze over the
wound, which provides a rough
surface for platelet adhesion
2. Applying pressure fractures cells,
which increases the release of
thromboplastin
What is a thrombus? Why are they
undesirable?
 A thrombus is a clot that develops
and persists in an unbroken blood
vessel.
 If large enough, it may prevent blood
flow beyond the blockage
What is an embolus? When does it
become a problem?
 An embolus is a thrombus that floats
freely in the bloodstream. It becomes
a problem when it lodges in a blood
vessel too narrow to pass through.
What causes undesirable clotting?
 Anything that roughens the
endothelium of a blood vessel and
encourages clinging of platelets
causes undesirable clotting
What is hemophilia? How can it be
controlled?
 Hemophilia is a hereditary bleeding
disorder that results from a lack of
any of the factors needed for clotting.
It can be controlled through injections
of genetically engineered clotting
factors.
What is an antigen? What is
agglutination?
 An antigen is a substance that the
body recognizes as foreign. It
stimulates the release of antibodies to
attack it.
 Agglutination is building of antibodies
to RBC’s, which causes them to clog
in blood vessels.
Which antigens are inherited for
each of the four blood types?
Blood Type
Antigens
Blood Received
AB
A,B
A, B, AB, O
A
A, anti-B
A, O
B
B, anti-A
B, O
O
anti-A, anti-B
O
Describe the procedure for testing
an individual’s ABO blood type:
1. Test blood by mixing it with 2
different types of immune serum—
anti-A and anti-B
2. Agglutination of the sample with 1,
both, or neither of the sera
determines blood type