CHAPTER 8
Blood and Hemopoiesis
143
SYNOPSIS 8-1
Life Spans, Counts, and Sizes of Blood Cells
Leukocytes
: Total number count is 4,500 to 11,000/mm
3
.
Erythrocytes
: Life span is about 120 days, count is 4,200,000 to 5,900,000/mm
3
(male 4,500,000–5,900,000/mm
3
; female
4,200,000–5,400,000/mm
3
); size is 7 to 8
μ
m (in diameter).
Platelets (thrombocytes)
: Life span is 8 to 12 days, count is 150,000 to 400, 000/mm
3
; size is 1 to 4
μ
m.
Monocytes
: Duration in circulation is a few hours to a few days before differentiating (a macrophage’s life span is up to
several months); count is 200 to 900/mm
3
; size is 12 to 15
μ
m.
Lymphocytes
: Life span is a few days to years; count is 1,000 to 4,000/mm
3
; size is 6 to 12
μ
m.
Neutrophils
: Duration in circulation is a few hours, life span is about 8 days; count is 3,500 to 7,000/mm
3
; size is 9 to 12
μ
m.
Eosinophils
: Life span is uncertain, likely a few days; count is 50 to 450/mm
3
; size is 9 to 14
μ
m.
Basophils
: Life span is uncertain, likely a few days; count is 0 to 200/mm
3
; size is 8 to 10
μ
m.
Clinical lab blood counts measure
total number
count of white blood cells ([WBCs] leukocytes/mm
3
) and
differential
counts
(percent of each type of leukocyte [Table 8-1]).
Absolute numbers
of WBCs can be calculated by multiplying total
number/mm
3
times percent of each type of leukocyte.
Shift to left
: Increase in number of immature leukocytes (especially neutrophils in band forms), which suggests high
demand because of infection or acute infl ammation (normal range of band leukocyte is 2%–6%).
Shift to right
: Absence of immature leukocytes in differential count of leukocytes.
Figure 8-7A.
Eosinophil, blood smear.
Wright stain,
3
754; inset
3
1,569
Eosinophils
have a two- to three-lobed (segmented) nucleus,
numerous
specif c
(
eosinophilic
)
granules
, and a few
azuro-
philic
granules
in the cytoplasm.
SpeciF c granules
contain
acid hydrolases
,
peroxidase
,
histaminase
,
basic protein
and
eosinophil cationic proteins
, which have antihelminthic
properties.
Azurophilic granules
contain mainly
lysosomal
enzymes
. Normally, the bone marrow contains a large
reserve pool of eosinophils (and other granulocytes) ready
for deployment on demand. Eosinophils have a life span of
a few days in circulating blood, although they can survive
longer in the tissues. They are commonly found in the con-
nective tissue of the digestive tract. Some of the granules
in eosinophils are highly toxic to parasitic worms such as
schistosomes. Eosinophils also play a role in moderating
infl
ammation resulting from an allergic reaction. They selec-
tively ingest and degrade antigen-antibody complexes and
also degrade histamine, therefore limiting infl
ammation.
D. Cui
Eosinophil
Neutrophil
Eosinophil
A
D. Cui
Neutrophil
Basophil
Neutrophil
Basophil
B
Figure 8-7B.
Basophil, blood smear.
Wright stain,
3
754; inset
3
1,569
Basophils
are the least numerous in the blood circulation,
comprising less than 1% of the leukocytes. It is therefore
difF cult to F nd them in normal blood smears. They have a
two- to three-lobed nucleus and large granules in the cyto-
plasm. These granules stain deep violet with Wright stain
and are distributed unevenly in the cytoplasm.
Specif
c gran-
ules
in basophils contain
heparin
,
histamine
,
peroxidase
,
and
eosinophil and neutrophil chemotactic ±actors
(attracts
eosinophils and neutrophils to the site).
Azurophilic gran-
ules
are also present in basophils. Basophils have a similar
function to mast cells in connective tissue. They contrib-
ute to allergic reactions by releasing histamine and heparin
to produce infl
ammation at the allergic reaction site. (±or
details, see ±ig. 4-4B).
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