Page 303 - Anatomy and Physiology of Farm Animals, 8th Edition

288 / Anatomy and Physiology of Farm Animals

• Compare and contrast the components 9. Assistance with the defense of the body
of serum versus plasma.
against disease by providing antibodies,
VetBooks.ir • What are the major contributors to cells, and other factors of body defense
(see Chapter 16)
plasma osmolality and oncotic pressure?
Integrate this knowledge with Chapter 23
to determine how normal renal physiology Blood consists of cells and other cell‐
helps maintain these constituents and like formed elements suspended in a fluid
normal blood pH. called plasma. Some of its functions are
specific to individual cells; for example,
erythrocytes are primarily responsible
ingle‐celled organisms that live in sea- for the transport of oxygen. Other func-
Swater have an external environment tions, such as assisting with body defense,
that provides all the needs of the organ- involve a variety of blood cells and other
isms, such as food, disposal of excreted plasma components. Blood volume is the
wastes, and relatively constant conditions total amount of blood in an animal’s body,
for maintenance of life. As the complexity including formed elements and plasma.
of organisms increases, the problem of Typical values given as a percentage of
supplying each cell with a proper environ- body weight are 7 to 9%. Lean, muscular,
ment becomes more acute. Higher forms athletic animals tend to have higher per-
of animals have developed circulating centages than animals with more body
blood, and the fluids derived from it, as a fat. (Specific gravity is an index, or ratio,
means of maintaining a relatively constant of the weight of a substance to the weight
environment for all cells. of an equal volume of water. A specific
gravity greater than 1 means that an equal
volume of the substance weighs more
Blood than water, at 1 g/mL. Blood and plasma
have slightly higher specific gravities than
water, primarily because of the blood
Most of the functions of blood are included cells and proteins, but the slight differ-
in the following list:
ence is usually disregarded when estimat-
1. Distribution of nutrients absorbed from ing blood or plasma volumes based on
the digestive tract body weight.)
2. Transport of oxygen from the lungs to A large number of plasma proteins are
cells throughout the body suspended in the plasma, and electrolytes
+
3. Transport of carbon dioxide from (e.g., Na , K , and Cl ) and other substances
−
+
metabolizing cells to the lungs (e.g., glucose and urea) are dissolved in
4. Transport of waste products from the plasma. While there are some minor
metabolizing cells to the kidneys for species differences (e.g., adult ruminants
excretion typically have slightly lower values for
5. Transport of hormones from endocrine blood glucose than other mammals), the
glands to target cells values in Table 15‐1 are typical normal
6. Assistance in body temperature control ranges for the major chemical constitu-
by transporting heat from deeper struc- ents of mammalian plasma.
tures to the surface of the body Plasma is a subdivision of a larger body
7. Assistance in maintaining a constant fluid compartment known as extracellular
pH of body fluids by providing chemical fluid, or ECF (see Chapter 2). Interstitial
buffers fluid, fluid outside of cells but not within
8. Assistance with the prevention of exces- vessels, is the other subdivision of the ECF
sive loss of blood from injuries by provid- compartment. The primary difference
ing proteins and other factors necessary between interstitial fluid and plasma is that
for blood coagulation plasma contains a much higher concentration