disease is not treated early on, it may
become more difficult to cure the disease.
The best way to prevent Lyme disease is
to stay away from places with ticks.
Ticks often live in shady, wooded areas.
People also can use an insect spray to
keep ticks away. If ticks do land on the
skin, people should remove them immediately.
#More to explore
Bacteria • Disease, Human • Tick and
Mite
Lymphatic
System
Humans and many other animals have a
lymphatic system, which helps the body
to fight disease. In this way the lymphatic
system is a part of the immune
system. The lymphatic system also carries
fluid throughout the body. In this
way it is a part of the circulatory system.
Major parts of the lymphatic system
include the lymphatic vessels, the lymph
nodes, and cells called lymphocytes. The
spleen, the tonsils, the appendix, bone
marrow, and the thymus also belong to
the lymphatic system.
Lymphatic Vessels
Lymphatic vessels run throughout the
body. These vessels collect extra fluid
from the body’s tissues. This fluid is
called lymph. Lymph carries wastes and
The lymphatic system fights disease and
carries fluid throughout the body.
BRITANNICA STUDENT ENCYCLOPEDIA Lymphatic System 189
certain nutrients, especially proteins.
Lymph flows from the lymphatic vessels
into the blood at a vein near the heart.
Lymphatic vessels also collect foreign
substances, called antigens, from the
tissues. Antigens include such things as
bacteria and viruses, which can cause
disease.
Lymph Nodes and Other
Organs
Lymph nodes, or lymph glands, are
small, bean-shaped organs. The human
body has thousands of lymph nodes.
They are found at certain points along
the lymphatic vessels. They are clustered
in such places as the neck, the armpits,
the knees, and the groin. Lymph nodes
remove antigens from the lymph.
Lymph nodes also hold antigen-fighting
cells called lymphocytes.
Other organs of the lymphatic system
also contain lymphocytes. The spleen
sits behind the stomach. It filters antigens
from the blood. The tonsils trap
antigens in the throat. The appendix
and other areas in the intestines trap
antigens, too.
Lymph vessels and blood vessels both carry white blood cells. But lymph vessels carry
lymph, not blood. They also carry nutrients that would not fit inside small blood vessels.
190 Lymphatic System BRITANNICA STUDENT ENCYCLOPEDIA
Lymphocytes
Lymphocytes are white blood cells. They
begin in bone marrow, which is a soft
tissue inside the bones. Some lymphocytes,
called B cells, develop in the bone
marrow. Other lymphocytes, called T
cells, travel to the thymus to develop
further. The thymus is a pyramid-shaped
organ that lies beneath the breastbone.
Lymphocytes travel through the lymph
and the blood. They collect in the
lymph nodes and other lymphatic
organs. They work to destroy antigens
that could harm the body.
#More to explore
Blood • Circulatory System • Immune
System
Lynx
Lynx are wild cats that live in the forests
of Europe, Asia, and northern North
America. They are known for their sharp
vision.
Lynx are about 30 to 40 inches (80 to
100 centimeters) long, without the short
tail. They weigh 20 to 45 pounds (9 to
20 kilograms). Lynx have long legs and
large, furry paws that help them move
through snow. Their thick fur helps to
keep them warm in cold weather. The
fur is yellowish brown to gray, with
darker brown and black patches. It is
bushy on the neck. The ears and tail
have black hair at the tip.
Lynx live alone or in small groups. They
hunt at night. Lynx eat birds and small
animals. Some lynx, such as the Eurasian
lynx, will eat larger prey such as deer.
Canadian lynx eat mostly snowshoe
hares. Lynx like to sneak up on their
prey rather than chase it down.
Lynx are good swimmers and climbers.
They also can make great leaps. Lynx are
generally silent, except during the mating
season.
Lynx are closely related to the bobcat
and the caracal. The bobcat is also called
the bay lynx. It is common to many
parts of the United States and has yellowish
brown fur tinged with red. Its fur
also has black spots. The caracal is sometimes
called the Persian, or desert, lynx.
It is found in hills, deserts, and plains of
Africa, the Middle East, and Asia. It has
a reddish brown coat.
#More to explore
Cat
Lynx have large paws that help the animals
move through snow.
BRITANNICA STUDENT ENCYCLOPEDIA Lynx 191
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