How the Lymphatic System
VESSELS: These are a system of ducts that collect fluid
from the body tissues, deliver it to the filtering lymph nodes and
transport it to the heart, where it rejoins the body's main
circulatory system. Lymphatic vessels start as microscopic
tubes in the spaces between cells and branch into larger vessels
throughout the body. Like veins, the vessels contain valves
that help maintain the flow of lymph back to the heart.
Located behind the breastbone, the twin lobed thymus gland
converts lymphocytes into more specialized T lymphocytes. Most
of this work is completed by puberty after which the thymus begins
oval structures that trap invading bacteria and viruses are
distributed along the network of lymph vessels and in the clusters
around the neck, armpit and groin. In response to infection
lymphocytes in the gland divide and proliferate. This is why
your neck glands swell when you have a throat infection. Each
node has vessels leading in and out of the gland and its own blood
These oval pads of tissue at the back of the throat protect
against infection of the upper respiratory tract. Tonsils
sometimes become infected by the very microorganisms they fight.
Doctors may remove the tonsils, if infections recur and/or resist
This fist sized spongy organ breaks down worn out red blood
cells and produces some of the lymphocytes and other infection
fighting components of the immune system.
MARROW: The soft fatty inner part of a bone, the marrow
produces all of the body's red blood cells and platelets and most of
the white blood cells.