536
UNIT FOUR
TABLE
14.6
|
Plasma Proteins
Protein
Percentage
of Total
Origin
Function
Albumin
60%
Liver
Helps maintain colloid
osmotic pressure
Globulin
36%
Alpha
globulins
Liver
Transport lipids and fat-
soluble vitamins
Beta
globulins
Liver
Transport lipids and fat-
soluble vitamins
Gamma
globulins
Lymphatic
tissues
Constitute the antibodies of
immunity
Fibrinogen
4%
Liver
Plays a key role in blood
coagulation
W
hen twenty-three-year-old maga-
zine editor Erin Zammett Ruddy
had a routine physical examination
in late 2001, she expected reassurance that her
healthy lifestyle had indeed been keeping her
healthy (±
gure 14A). After all, she felt great. What
she got, a few days later, was a shock. Instead
of having 4,500 to 10,000 white blood cells
per microliter of blood, she had more than ten
times that number—and many of the cells were
cancerous. Erin had chronic myeloid leukemia
(CML). Her red bone marrow was flooding her
circulation with too many granulocytes, most of
them poorly di²
erentiated.
Another type of leukemia is lymphoid, in
which the cancer cells are lymphocytes, pro-
duced in lymph nodes. Both myeloid and lym-
phoid leukemia can cause fatigue, headaches,
nosebleeds and other bleeding, frequent respi-
ratory infections, fever, bone pain, bruising, and
other signs of slow blood clotting. The symp-
toms arise from the disrupted proportions of the
blood’s formed elements and their malfunction
gure 14B).
Immature white blood cells increase the risk
of infection. Leukemic cells crowd out red blood
cells and their precursors in the red marrow,
causing anemia and resulting fatigue. Platelet
deficiency (thrombocytopenia) slows clotting
time, causing bruises and bleeding. Finally,
spread of the cancer cells outside the marrow
painfully weakens surrounding bone. Eventually,
without treatment, cancer cells spread outside
the cardiovascular system, causing other tissues
that would normally not produce white blood
cells to do so.
Leukemia is also classified as acute or
chronic. An acute condition appears suddenly,
symptoms progress rapidly, and without treat-
ment, death occurs in a few months. Chronic
forms begin more slowly and may remain unde-
tected for months or even years or, in rare cases,
decades. Without treatment, life expectancy after
symptoms develop is about three years.
Erin was diagnosed just as a new drug was ³
y-
ing through clinical trials. She became one of the
±
rst patients to take Gleevec, now standard treat-
ment for CML and several other cancers. Gleevec
speci±
cally targets cancer cells by nestling into ATP-
binding sites on a type of enzyme called a tyrosine
kinase, which blocks the message to divide. The
drug worked so well that it was approved in just ten
weeks. People with leukemia have other options
too, such as standard chemotherapies, and bone
marrow and stem cell transplants.
14.2
CLINICAL APPLICATION
Leukemia
FIGURE 14A
´“My´third´
bone marrow biopsy—you
never get used to the pain,”
said Erin Zammett Ruddy.
The drug Gleevec has treated
her leukemia. Bone marrow
biopsies are required at
regular intervals, even after
successful treatment, to be
certain that the disease has
not returned.
PRACTICE
28
List three types of plasma proteins.
29
How do albumins help maintain water balance between the
blood and the tissues?
30
Which of the globulins functions in immunity?
31
What is the role of ±
brinogen?
Gases and Nutrients
The most important
blood gases
are oxygen and carbon dioxide.
Plasma also contains a considerable amount of dissolved nitro-
gen, which ordinarily has no physiological function. Chapter
19 (pp. 762–766) discusses blood gases and their transport.
The
plasma nutrients
include amino acids, simple sug-
ars, nucleotides, and lipids absorbed from the digestive tract.
For example, plasma transports glucose from the small intes-
tine to the liver, where it may be stored as glycogen or con-
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