A lymph node is a small, bean-shaped structure that is part of the lymphatic system, and that plays a key role in immune response and defense against infections. The lymphatic system helps filter and drain lymph, a fluid that contains white blood cells and waste products, from various parts of the body.
Key points:
Structure and Location: Lymph nodes are typically small, ranging from a few millimeters to about 2 centimeters in size. They are distributed throughout the body and are often found in clusters. Common locations include the neck, armpits, groin, chest, and abdomen.
Function: Lymph nodes act as filters for lymph, trapping and removing foreign particles, such as bacteria, viruses, and abnormal cells (e.g., cancer cells). As lymph passes through the nodes, immune cells within them (including lymphocytes and macrophages) help detect and combat potential threats.
Swelling and Tenderness: When the body is fighting an infection, the associated lymph nodes may become enlarged, tender, or palpable. This is a common sign that the immune system is actively responding to an infection or inflammation in the nearby area.
Primary and Secondary Lymphoid Organs: Lymph nodes are considered secondary lymphoid organs, meaning they are sites where immune responses are initiated. Primary lymphoid organs, such as the bone marrow and thymus, are involved in the production and maturation of immune cells.
Immune System Surveillance: Lymph nodes play a crucial role in immune system surveillance, helping identify and respond to foreign invaders. They are part of a broader network of tissues and organs that collectively work to protect the body from infections and diseases.