Post written by Ramesh Venkatraman
Breast cancer among
women is on the rise across the world and also in India. In this 3-part article
we will look at the lymphatic system and its role in human health (part-1), lymphadema
following breast cancer therapy (part-2),and in part-3 we will look at some
simple and natural methods in managing lymphadema, a common condition that
occurs in women post breast cancer therapy.
The circulatory
system:
Before we look at the lymphatic system, let us briefly look at the normal blood circulatory system in humans. The circulatory system consisting of the blood vessels and blood (along with its constituents) plays a vital role in carrying oxygen and nutrients to the various parts of the body and also in transporting and removing waste products of metabolism. The actual exchange of substances (food and waste) occurs at the level of the capillary beds (a dense minute network of blood vessels). The capillaries are microscopically minute blood vessels made up of only one layer of cells. The capillary walls are so thin that they are actually translucent - It is this “thinness” that makes it possible for substances such as oxygen, glucose, and waste materials to quickly (an easily) pass through their walls, while on their way to or from tissue cells.
Before we look at the lymphatic system, let us briefly look at the normal blood circulatory system in humans. The circulatory system consisting of the blood vessels and blood (along with its constituents) plays a vital role in carrying oxygen and nutrients to the various parts of the body and also in transporting and removing waste products of metabolism. The actual exchange of substances (food and waste) occurs at the level of the capillary beds (a dense minute network of blood vessels). The capillaries are microscopically minute blood vessels made up of only one layer of cells. The capillary walls are so thin that they are actually translucent - It is this “thinness” that makes it possible for substances such as oxygen, glucose, and waste materials to quickly (an easily) pass through their walls, while on their way to or from tissue cells.
The lymphatic circulation:
While the exchange of substances mostly takes place through the circulatory system, certain large substances that cannot enter or return through the micro pores of the capillary including excess of fluid and large-sized protein molecules forms what is called the lymph or lymphatic fluid. Due to the pumping action of the heart, blood pressure is created and blood oozes out of the capillaries into the spaces between tissue cells - In the tissues this fluid is called interstitial fluid or tissue fluid. Most of this fluid goes back into the circulatory system via the same capillary pores. The remainder of the interstitial fluid enters the lymphatic circulatory system flows through the lymphatic ducts and finally is returned back to the circulatory system.
Once the interstitial fluid enters into the lymphatic system it is called lymph. The lymphatic system is made up of a network of tubes similar to the blood vessels but with one major difference. These tubes are “blind-ended” i.e. they are unidirectional; the lymphatic fluid does not take the circular route of blood (going round and round). The lymphatic capillaries are similar to the blood capillaries in that they are also made up of a single layer of cells but differ from the capillaries in the size of their micro pores - These pores are larger and allow larger molecules to enter inside and eventually return back to the general blood circulation.
From the lymphatic capillaries, the lymph flows through progressively enlarging vessels lymphatic venules, followed by lymphatic veins. Finally the lymph is emptied into two large lymphatic ducts called the right lymphatic duct and the thoracic duct. 75% of the lymph is emptied into the thoracic duct and the remaining is emptied into the right lymphatic duct. From these ducts, the lymph is emptied into the large veins present in the neck region from where they go back into the general circulation. The lymphatic vessels appear like a string of beads traversing across the body. The bead like appearance is caused by the presence of valves that help the one way flow of lymph.
While the exchange of substances mostly takes place through the circulatory system, certain large substances that cannot enter or return through the micro pores of the capillary including excess of fluid and large-sized protein molecules forms what is called the lymph or lymphatic fluid. Due to the pumping action of the heart, blood pressure is created and blood oozes out of the capillaries into the spaces between tissue cells - In the tissues this fluid is called interstitial fluid or tissue fluid. Most of this fluid goes back into the circulatory system via the same capillary pores. The remainder of the interstitial fluid enters the lymphatic circulatory system flows through the lymphatic ducts and finally is returned back to the circulatory system.
Once the interstitial fluid enters into the lymphatic system it is called lymph. The lymphatic system is made up of a network of tubes similar to the blood vessels but with one major difference. These tubes are “blind-ended” i.e. they are unidirectional; the lymphatic fluid does not take the circular route of blood (going round and round). The lymphatic capillaries are similar to the blood capillaries in that they are also made up of a single layer of cells but differ from the capillaries in the size of their micro pores - These pores are larger and allow larger molecules to enter inside and eventually return back to the general blood circulation.
Image Source: http://en.wikipedia.org/wiki/File:Illu_lymphatic_system.jpg
From the lymphatic capillaries, the lymph flows through progressively enlarging vessels lymphatic venules, followed by lymphatic veins. Finally the lymph is emptied into two large lymphatic ducts called the right lymphatic duct and the thoracic duct. 75% of the lymph is emptied into the thoracic duct and the remaining is emptied into the right lymphatic duct. From these ducts, the lymph is emptied into the large veins present in the neck region from where they go back into the general circulation. The lymphatic vessels appear like a string of beads traversing across the body. The bead like appearance is caused by the presence of valves that help the one way flow of lymph.
Lymph nodes and function:
Scattered along the pathway of the lymphatic system are
several clusters of lymph nodes. These lymph nodes filter the lymphatic fluid
as they traverse across the lymphatic system. This filtering function of the
nodes plays an extremely important role of removing dead cells, abnormal,
cancerous cells, and bacteria. Without this important biological filtration
function dangerous bacteria, cancerous cells etc. would enter the circulatory
system and play havoc causing life-threatening infections and diseases. The
fact is that in spite of such robust in-built protection infections and
diseases do occur.
End of Part-1. In Part-2 we will look at infections of the lymph nodes
in general and lymphadema post breast cancer therapy in particular. Click here to go to Part-2
Extremely informative. Easy to relate to for any layman/woman. Infections of lymph nodes ...?? look forward to this section.
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