Download B. Structure

Objective 9
Leukocytes
A. Normal Values – less than 1% of total blood volume (rememebr
the picture of the test tube!)
Adults:
4800 – 10,800 leukocytes /mm3 blood (higher
values in newborns, infants and children)
B. Structure:

are nucleated

contain organelles

diameters range from 8 – 24 m

may contain cytoplasmic granules (agranulocytes vs. granulocytes)
Granulocyte
Agranulocyte
In what structural ways are leukocytes different than erythrocytes?
In what functional ways are leukocytes different than erythrocytes?
Where do they do
their jobs?
Diapedesis – leukocytes leave capillary and enter tissue
Chemotaxis – follow chemical signals to site of infection in the tissue
C. Leukocyte Classes
Granulocytes:
Neutrophil (also called a polymorphonuclear cell)

diameter = 10-12 m

cytoplasmic granules stain pale lavender

lobed nuclei (3-6 lobes)
% of total leukocytes: 50-70%

Granules contain lysosomal
enzymes and defensins
Neutrophils are quick acting
phagocytes (1st responders)
Typical Neutrophil
They are quick but weak!
Immature Cell - Band
Eosinophil

diameter = 10-14 m

large granules which stain red (major basic protein)

bilobed nucleus

represent 2-4% of the total WBC count
Granules contain digestive
enzymes
Are antiparasitic
Phagocytize immune
complexes
Anti-allergy
Basophil

diameter = 8-10m

large granules which stain blue

U or S shaped nucleus

0.5 – 1% of total WBC
Granules contain:
histamine which induces inflammation and
vasodilation
heparin
an anticoagulant
2. Agranuloctes: lack visible cytoplasmic granules
Lymphocyte:

diameter 5-8 m (small), 10-12 m (medium) or 14-17 m (large)

20-25 % of the total WBC count

large, deep blue or slightly indented nucleus

thin rim of pale blue cytoplasm
T lymphocyte (T cells)
fight antigens directly
B lymphocytes (B cells)
divide to produce plasma
cells that secrete
antibodies
Monocytes




diameter = 18 m
nucleus is U shaped or kidney shaped
abundant pale blue cytoplasm
3 – 8 % of the total WBC
Are phagocytes – slow but strong
Develop into macrophages when
they migrate into connective tissue
Leukopoiesis is the
production of leukocytes

all leukocytes can be
made in red bone
marrow from
hemocytoblasts

lymphocytes can be
made in either red
bone marrow or
lymphoid tissues

the production of
lymphocytes is
stimulated by
interleukins and by
colony stimulating
factors (CSFs)
Objective 10
Leukopenia
White Blood Cell Disorders
circulating WBC count <4000/mm3 blood in adults
increases the susceptibility to infection
causes include bone marrow depression or destruction,
often due to drugs, radiation, infection, or autoimmune
conditions
Leukocytosis
circulating WBC count is >11,000/mm3 blood in affected
adults; is accompanied by bleeding, weight loss,
liver/spleen/lymph node enlargement or immunosupression;
suspect primary bone marrow disease
causes include infection, inflammation, malignancy,
allergic reactions, autoimmune disorders, genetic disorder,
extreme stress, other causes
Leukemia
Cancer in which an excessive
number of white blood cells
is produced
Classification:
Acute
disease progresses
rapidly
Chronic
disease progresses
slowly
Myelocytic
involves cells in the
myeloid pathway
Lymphocytic
involves cells in the
lymphocytic pathway
Causes:
cancer in which an abnormally high
number of WBCs are produced
Symptoms
anemia, fever, bruising/bleeding, bone
pain
Acute lymphocytic leukemia
Chronic lymphocytic leukemia
Infectious Mononucleosis
B lymphocytes are infected and proliferate in an
uncontrolled manner
signs include sore throat, fever, enlarged lymph
nodes. Enlarged spleen, lethargy, fatigue
cause:
Epstein Barr Virus
Objective 11
Platelets
A. Structure

are cell fragments

discoid in shape; diameter is 2-4 m

major internal proteins are actin and myosin
What are actin and myosin used for?

contraction
cytoplasmic storage granules:
 granules
dense granules
contain fibrinogen, factor V, factor VII, von
Willibrands factor, platelet factor 4 and
PDGF
contain serotonin, Ca2+, adenosine nucleotides
(ATP and APD), thromboxane A2 (a
prostaglandin)
B. Function:
Hemostasis
C. Platelet Production
platelets are produced in red bone marrow from
megakaryotyctes

Production is regulated by thrombopoietin and interleukins

Production takes 4-5 days; life span is 5-10 days
Average adult values:
150,000-400,000/mm3
blood
An additional 1/3rd is stored in the spleen