537
CHAPTER FOURTEEN
Blood
Plasma lipids include fats (triglycerides), phospholipids,
and cholesterol. Lipids are not water soluble and plasma is
almost 92% water, so these lipids are carried in the plasma
by joining with proteins, forming lipoprotein complexes.
PRACTICE
32
Which gases are in plasma?
33
Which nutrients are in plasma?
Nonprotein Nitrogenous Substances
Molecules that contain nitrogen atoms but are not proteins
comprise a group called
nonprotein nitrogenous substances
(NPNs). In plasma, this group includes amino acids, urea,
uric acid, creatine (kre
ah-tin), and creatinine (kre-at
ı˘-nin).
Amino acids come from protein digestion and amino acid
absorption. Urea and uric acid are products of protein and
nucleic acid catabolism, respectively, and creatinine results
verted to fat. If blood glucose concentration drops below the
normal range, glycogen may be broken down into glucose,
as described in chapter 13 (p. 509).
Recently absorbed amino acids are also carried to the liver.
Here they may be used to manufacture proteins or deaminated
and used as an energy source (see chapter 18, p. 704).
Another way that leukemia treatment is
improving is refining diagnosis by identifying
the proteins that leukemia cells produce. This
information is used to predict which drugs are
most likely to be effective and which will cause
intolerable side eF
ects or not work in particular
individuals. ±or example, some people with acute
lymphoblastic leukemia (ALL), diagnosed on the
basis of the appearance of the cancer cells in a
blood smear, do not respond to standard chemo-
therapy. However, DNA microarray (also called
DNA chip) technology revealed that the cells of
patients who do not improve produce diF
erent
proteins than the cancer cells of patients who
do respond to the drugs used to treat ALL—the
nonresponders have a diF
erent form of leukemia,
called mixed-lineage leukemia. These people
respond to diF
erent drugs.
As for Erin, she went oF
Gleevec to have a
baby and is doing well. If her leukemia should
return, and if Gleevec becomes ineF
ective, she
will have newer drugs to try that bind more
strongly to cancer cells or that ²
t slightly altered
resistant cancer cells.
(a)
FIGURE 14B
Leukemia and blood cells. (
a
) Normal blood cells (700
×
). (
b
) Blood cells from a person with granulocytic leukemia, a type of myeloid
leukemia (700
×
). Note the increased number of leukocytes.
(b)
As a rule, blood gases are evaluated using a fresh sample of whole
blood obtained from an artery. This blood is cooled to decrease the
rates of metabolic reactions, and an anticoagulant is added to pre-
vent clotting. In the laboratory, the levels of oxygen and carbon diox-
ide of the blood are determined, the blood pH is measured, and the
plasma bicarbonate concentration is calculated. Such information is
used to diagnose and treat disorders of circulation, respiration, and
electrolyte balance. Appendix B (p. 941) lists average values for these
laboratory tests.
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