Lymph node
Lymph nodes are small, bean-shaped structures that play a crucial role in the body's immune system, as part of the lymphatic system. They serve as filters for lymph fluid, containing specialized immune cells that help combat infections by trapping pathogens. Located throughout the body, particularly in the neck, armpits, and groin, lymph nodes can become swollen during infections or injuries as they work to filter out toxins and pathogens. This swelling may serve as a visible indicator that the immune system is actively responding to a threat.
Lymph nodes are also significant in cancer diagnoses, as cancerous cells can spread through the lymphatic system, leading to conditions like Hodgkin's lymphoma. Doctors often evaluate lymph nodes by performing biopsies to determine the presence of cancer cells, which can indicate the severity of cancer and its potential spread. Understanding the function and significance of lymph nodes can provide insights into both immune responses and cancer progression, illustrating their importance in maintaining health and diagnosing illnesses.
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Subject Terms
Lymph node
A lymph node is a small gland found in the body. Lymph nodes are part of the lymphatic system, which is an important part of the immune and circulatory systems. The lymphatic system rids the body of harmful toxins and wastes. It also transports lymphatic, or lymph, fluid, which contains white blood cells that aid in fighting infection, throughout the body. Lymph nodes play a prominent part in cancer diagnoses. Because the lymph network travels throughout the body, it provides an efficient means for cancerous cells to spread. If a lymph node is infected, the lymph network can transport cancerous cells to other parts of the body. Testing lymph nodes for cancer is one way doctors grade the severity of certain cancers.
Background
Italian physician Gaspare Aselli first noticed the lymphatic system in 1622. He was studying a dog and found that a set of anatomical objects resembling veins became milky in color after the dog ate. He called the milky fluid inside the veins chyle.
In 1650, English scientist John Pecquet acknowledged lymphatic tubes and lymph nodes as separate structures. He also discovered the cisterna chyli, the largest lymph vessel in the body. At this time, however, Pecquet still believed that the lymphatic system was a subset of the circulatory system. It was not until his contemporary, Olaus Rudbeck, began studying the lymphatic system that physicians realized the lymphatic system was a separate system of the body. Many physicians then began to study the lymphatic system.
Over time, physicians realized that overly swollen lymph nodes caused pain and discomfort. They experimented with various methods of draining swollen lymph nodes. Eventually, they developed precise treatments for a variety of illnesses related to swollen, painful lymph nodes.
Modern research has revealed a number of other functions of the lymphatic system. It showed that the lymphatic system produces white blood cells known as T cells (T lymphocytes) and B cells (B lymphocytes), which travel through the bloodstream helping the body fight infections. The lymphatic system also creates natural killer cells, which sit near important areas of the body to defend them against invading pathogens.
Overview
Lymph nodes are small, bean-shaped filters for lymph fluid. They are made of lymphatic tissue and are covered in a tough shell of connective tissue that allows liquid to pass through them. Lymph nodes help filter blood and contain specialized immune cells that help fight infection. Additionally, lymph nodes can trap potential pathogens, giving the body's immune system time to adapt to any new threats. Once an immune response has been formulated, the body can attack the trapped samples and destroy them. It can then send antibodies or other defense measures through the lymphatic system to other parts of the body.
The human body contains hundreds of lymph nodes. They are found in every part of the body, including the groin, neck, and head. Lymph nodes are not found in equal distribution. Areas where more blood flow is required demand a greater concentration of lymph nodes to filter blood and lymph fluid. The greatest number of lymph nodes are found in the neck, armpits, and groin.
When lymph nodes are filtering blood and lymph fluid, they retain any infected or impure fluid. During an infection or injury, lymph nodes may retain more fluid than normal. This can cause lymph nodes to become swollen. In areas with a high concentration of lymph nodes, the nodes can sometimes be seen protruding from the skin. Visible lymph nodes can be a sign that something is wrong with the body. Even if no other symptoms are present, swollen lymph nodes can mean that the body is working hard to filter a pathogen or other toxins out of the blood.
While lymph nodes are usually a hard line of defense against sickness, they can occasionally cause certain illnesses to spread. Cancer is a disease that causes irregular cells to replicate uncontrollably. When cancer infects the lymph nodes, it begins to disable the lymphatic system. Cancerous cells use the lymph nodes to spread throughout the body. Cancer reaches the lymph nodes in one of two ways: It spreads to the lymph nodes, or it develops in an infected lymph node. Cancer that develops in a lymph node is called Hodgkin's lymphoma, also known as Hodgkin's disease. Enlarged lymph nodes can be a sign of Hodgkin's lymphoma. Usually, a surgeon removes a part of the lymph node to check it for cancer cells in a process called a biopsy. If left unchecked, Hodgkin's lymphoma can spread through the entire lymphatic system and into other organs.
Other forms of cancer sometimes spread to the lymph nodes. When an aggressively spreading cancer takes root in a lymph node, it can begin to produce cancerous cells directly into the lymphatic system. This gives the cancerous cells a pathway to the entire body. Cancer growing in multiple places is much more difficult to treat than cancer growing in a single location.
Some doctors use a cancer's proximity to a lymph node as a means to address its severity. If a cancer is far from major lymph nodes, it will be more difficult for the cancer to spread. This cancer is usually removed with simple surgery. However, if the cancer is located close to lymph nodes, a greater chance exists that the cancer has spread and may be growing in other parts of the body.
Doctors cannot tell if a lymph node is infected by simply looking at it. Instead, when a surgeon attempts to remove the cancer, they will often remove a nearby lymph node. This lymph node can then be biopsied by a laboratory to check for cancerous cells. If cancer has spread into the lymphatic system, doctors will often prescribe chemotherapy, radiation, or other treatments to combat it.
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