Disorders in the Lymphatic System
Luke David Farrar
Introduction
Since the lymphatic system is an integral part of the body’s immune system, any issues with it can
lead to infections and disease. As well as containing lymphocytes, a type of white blood cell, to fight off
infections, the lymphatic system also acts as drainage for the body as it moves a fluid, now called lymph
after travelling through the lymphatic system, into the blood stream.
Some of the common disorders in the lymphatic system occur are lymphedema—a blockage leading
to a build-up of lymph, lymphadenitis—when a lymph node becomes infected by travelling through the
lymphatic system, and lymphoma, which is a type of cancer caused by white blood cells.
The Lymphatic System
Primarily a transportation system to bring lymph back into the blood stream through a network of
nodes and vessels that connect throughout the body. Additionally, there are 6 main organs in the system—
bone marrow, spleen, tonsils, mucous membranes, the thymus gland, and lymph nodes themselves. While
the lymphatic system is primarily for transport, it relies on muscle contractions to push lymph through the
system, so this process doesn’t occur where muscles are inactive. The system also produces specialised
white blood cells—covered further below.
, Lymph itself is collected from interstitial fluid (tissue fluid) which is located in between the cells of
all body tissue. This fluid, now entering the lymphatic system through lymph capillaries, is now referred to
as lymph. Interstitial fluid is mostly composed of plasma and is sometimes referred to as such, but also
contains nutrients and waste from metabolising cells. Also, while this fluid may contain some white blood
cells, it doesn’t contain any red blood cells since they are too large to enter the capillaries surrounding the
thin walls where the interstitial fluid is stored.
Once the lymph has diffused through the lymphatic system, the lymph collected from various places
in the body is emptied back into the central blood stream through the left or right subclavian vein. A
staggering 17 litres of the 20 litres collected daily is deposited back, whereas the other 3 litres travel through
a second system of lymphatic capillaries/veins. At this point, once the waste has been transported back, the
primary job of the lymphatic system has been completed.
Other than transportation and the production of white blood cells, the lymphatic system regulates
interstitial fluid pressure to increase the efficiency of substances, like gases, to the cell membrane.
Additionally, fat is transported from the digestive system and broken down so that they can fit through
capillaries and enter the blood stream.
Lymphocytes
T cells
Cells produced in the thymus gland with different roles. Cytotoxic cells locate cells infected with a
virus by the proteins they let off and attach themselves to the cell to rupture their cell membrane. Helper
cells latch onto b cells and activate a cell division to help with the production of antibodies. Once the other
cells have completed their job, regulatory t cells limit their response to infection, which prevents an
abnormal response in the immune system.
B cells
Produced in the bone marrow, it’s the b cells job to support t cells by providing antigens if they can
not locate it themselves. They also produce antibodies which are used to locate infected cells to be attacked
by the immune system or even remove it via blockage (the antibodies Y shape helps it latch onto the cell,
sometimes blocking off an important section of the virus and preventing mitosis).
Natural killer cells
These perform the same job as cytotoxic cells but can attack infected cells without the need for
activation by antibodies/b cells.
Organs
Categorised as a secretory unit in the body, glands play a huge part in the lymphatic system as they
secrete white blood cells. Organs, on the other hand, are simply defined as “a group of tissues in a living
organism that have been adapted to perform a specific function.” (organ | Definition, Types, & Facts, 2021)
The spleen
Filters old blood cells, helping to control the level of total blood cells, and fight blood-borne germs.
A soft, purple organ, and the largest in the lymphatic system, found in the ribcage. Despite its size, it is
possible to live without the spleen since the liver completes most of the same functions.
The thymus
A small gland located in the centre of the body behind the breastbone. T cells are produced in the
thymus, which are necessary for the body’s adaptive immune system to target foreign, unwanted cells. Once
a person has reached puberty, the thymus gland has produced all of the t cells necessary and begins to be
replaced by fat through adulthood until it becomes wholly fatty tissue.
Tonsils
These are small lumps of tissue at the back of the throat and naval cavity that prevent germs entering
the body through the mouth/nose. Many white blood cells are present on the tonsils which kill the germs
after they have been stuck to the exterior via ventilation.
Lymph nodes
Pea-sized glands located throughout the lymphatic system that produce white blood cells and filters
lymph to remove pathogens. When the body is fighting an infection, the lymph nodes may become visibly
swollen and irritative for around two weeks but is ultimately harmless.
Valves
