306 Chapter 13
Plasma (^)
(55% of (^)
total (^)
volume) (^)
(^) Erythrocytes Thrombocytes (^)
(platelets) (^)
Formed (^)
elements (^)
(45% of
total (^)
volume) (^)
(^) Neutrophil Basophil Eosinophil Lymphocyte Monocyte (^)
Test tube
(^)
(^)
containing
Leukocytes
(^)
whole blood (^)
Figure 13- 1 The major components of blood.
(^) ®
Learning
Cengage ©
as a waste product of cellular metabolism, to the lungs to be
expelled from the body. Blood carries nutrients, ions, and
water from the digestive tract to all cells of the body. It also
transports waste products from the body’s cells to the sweat
glands and kidneys for excretion.
Blood transports hormones from endocrine glands to
target organs in the body. It also transports enzymes to
body cells to regulate chemical processes and chemi-cal
reactions. Blood helps regulate body pH through buffers
and amino acids that it carries. The normal pH of blood is
slightly basic (alkaline) at 7.35 to 7.45. Blood plays a role
in the regulation of normal body tem-perature because it
contains a large volume of water (the plasma), which is an
excellent heat absorber and coolant.
Blood helps to regulate the water content of cells
through its dissolved sodium ions; thus, it plays a role in
the process of osmosis. It is through the clotting mecha-
nism that blood helps prevent fluid loss when blood ves-
sels and tissues are damaged. Finally, blood plays a vital
role in protecting the body against foreign microorgan-isms
and toxins through its special combat-unit cells, the
leukocytes.
The Classification of Blood Cells
and The Composition of Plasma
The most common classification of the formed elements or
cells of blood is:
A. Erythrocytes or red blood cells (RBCs), which make
up about 95% of the volume of blood cells.^
B. Leukocytes or white blood cells (WBCs) are divided
into two subcategories: the granular leukocytes and
the agranular or nongranular leukocytes.^
- The granular leukocytes have granules in their
cytoplasm when stained with Wright’s stain.
There are three types:^
a. Neutrophils (NOO-troh-fillz), which make
up 60% to 70% of WBCs
b. Eosinophils (ee-oh-SIN-oh-fillz), which
make up 2% to 4% of WBCs
c. Basophils (BAY-soh-fillz), which make
up^ 0.5% to 1% of WBCs^ - The agranular or nongranular leukocytes do not
show granules in their cytoplasm when stained
with Wright’s stain.