Page 315 - Anatomy and Physiology of Farm Animals, 8th Edition

300 / Anatomy and Physiology of Farm Animals

is a lipid‐soluble essential vitamin whose and these join to form larger vessels resem-
bling veins. The direction of lymph flow is
normal intestinal absorption requires bile
VetBooks.ir salts. If the liver is diseased or the bile duct from small lymphatics to large ones. The
largest of the lymphatic vessels join with
is obstructed, the resultant lack of bile in
the gut reduces the absorption of lipids large veins just cranial to the heart, and
and vitamin K. Bacteria in the mammalian here all lymph returns to the blood. Edema
intestine also synthesize absorbable vita- is an abnormal accumulation of fluid
min K. within the interstitial space. Blockage of
Dicumarol is a toxic form of a general lymphatic vessels can produce edema
class of compounds known as coumarins. within the area normally drained by those
Dicumarol, found in spoiled sweet clover lymphatics.
hay or silage, is antagonistic to vitamin K Lymph is a clear, colorless liquid some-
and reduces the synthesis of vitamin K‐ what similar to blood plasma, from which
dependent clotting factors, including it is derived. Lymph usually contains
prothrombin. Dicumarol inhibits the numerous lymphocytes, inorganic salts,
clotting of blood and sweet clover poisoning glucose, proteins, and other nitrogenous
is the hemorrhagic condition resulting substances. Neutrophilic leukocytes are
from excessive dicumarol ingestion. not normally present in great numbers
Clinical signs are related to reductions in except during acute infections.
the ability of blood to clot. Small cuts or Lymph derived from the intestine during
bruises may result in bleeding that is digestion may contain large quantities of
difficult to stop. Warfarin is another lipids, giving it a milky appearance. This
coumarin and vitamin K antagonist that milky lymph, called chyle, results from the
is used commercially in rodent poisons. absorption of lipids into the lacteals, the
small lymphatics of the intestine.

Lymph
Serous Fluids
Normally there is very little net egress of
fluid as blood flows through capillaries. Serous fluids in the body cavities include
Recall that the capillaries are relatively peritoneal, pleural, and pericardial fluid.
impermeable to plasma proteins, and these Normally, these fluids are present as a thin
generate an effective osmotic force to film that reduces friction between apposed
retain fluid within the vessels. However, surfaces and lack any significant cellular
there is a relatively small net loss of both content. Inflammation or infection of the
protein and fluid from capillaries. These serous membranes causes increased pro-
are normally taken up by a system of small duction of serous fluids and can result in a
lymphatic vessels, and the resultant fluid cellular exudate in the body cavity associ-
is lymph. ated with the serous membrane. Examples
Lymphatic vessels begin as blind‐ending are pleuritis (pleurisy), peritonitis, and
vessels similar in structure to capillaries, pericarditis.