Lymph Nodes

What are the functions of lymph nodes and where are they located in the body? The lymphatic system is a collection of tissues, ducts, nodes (glands), and organs that collect and filter excess tissue fluid (lymph), then return it to the bloodstream. The lymphatic system is a vital part of the body’s defense system.

What is lymph?
It is a clear, yellow liquid that moves through the arteries of the body. Lymph fluid circulates through the tissues to cleanse them and hold them firmly in place.

Lymph is formed when fluid moves out of the capillary beds in tissues due to hydrostatic pressure. About 10% of blood volume is converted into lymph.

The composition of lymph is almost similar to blood plasma, and most of its volume (about 95%) consists of water. 5% of the remaining volume of lymph consists of proteins, lipids, carbohydrates (mainly glucose), various ions and some types of cells (mainly lymphocytes). Keep in mind that the composition of lymph can vary depending on where it is produced in the body. For example, chyle (lymph produced in the digestive tract) is rich in fat.

An average adult produces between 3 and 4 liters of lymph per day. Although this amount can be different during illness.

Their Function


In fact, lymph glands or lymph nodes are the first line of defense of the body’s immune system and protect the body against invaders such as bacteria or viruses that can make you sick. These lymph nodes are small, round or bean-shaped. Lymphatic vessels (tubes like veins) connect the lymph nodes to each other. These channels transport lymph fluid.


There are many white blood cells in the nodes. These blood cells help neutralize foreign agents such as bacteria and protect the body against harmful microbes.

There are two types of lymphocytes:
B cells: B cells produce antibodies that attach to microbes and let the immune system know that it needs to destroy these microbes.
T cells: T cells have various functions. Some of them kill germs, while others regulate immune cells. T cells allow the body to know when to produce more or less of certain immune cells. Memory T cells are a type of T cell that remain inactive after an infection and become active again when faced with the same infection.


Structure of lymph nodes

The length of lymph nodes varies from about 0.1 to 2.5 cm. They are enclosed in a capsule and there is a depression on their surface (along one of the longitudinal axes) called the hilum. The hilum is the point where the ducts that carry nutrients and lymphocytes enter the lymph node and the ducts that leave the lymph node. Afferent ducts enter the lymph nodes through the capsule, and efferent ducts leave these glands through the hilum. The first one takes the lymph from the peripheral and non-central areas to the glands, while the second one takes the filtered lymph out of the glands and returns it to the blood circulation.

Where are they located in the body?
On average, an adult has about 400 to 450 different lymph nodes spread throughout the body. However, most of them are inside the abdomen. Also, the human body has a large number of lymph nodes in the neck, groin and chest.

What is the cause of swollen lymph nodes?


Swollen lymph nodes are usually the result of a bacterial or viral infection. They play a vital role in the immune system’s fight against infections. They like a strong monitoring and surveillance system, monitor the entry of any foreign agent into the body and report to the immune system as soon as possible.

These glands become larger in infectious conditions and contain more immune cells. The reason for this prominence is the increase in the number of white cells to fight foreign agents. Neck, armpit and groin lymph nodes are usually earlier and more affected by infection than other lymph nodes, and swelling occur more often in them. In most cases, with the subsidence of inflammation and infection in the body, the lymph nodes also return to their original state.

By roya

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