Final answer:
Lymph nodes are bean-shaped structures throughout the body that become palpable when swollen, indicating immune system activity, often due to infection or other conditions like lymphoma.
Step-by-step explanation:
The bean-shaped structures found throughout the body, with palpable groups in the groin, axilla, and neck, are called lymph nodes. Lymph nodes are a vital part of the immune system, and they can become enlarged when the body is fighting off an infection or in other circumstances such as a reaction to certain diseases like lymphoma.
The swelling of lymph nodes is a signal that the immune system is active, as the nodes filter lymph and store lymphocytes, which play a critical role in combating infections. When infections do not respond to treatment and swelling persists, it could point to more serious conditions such as cancer of the lymphocytes, known as lymphoma, which requires further medical evaluation including a biopsy.
Lymph nodes are surrounded by a tough capsule of connective tissue and have an internal structure that supports their function in immune responses. They are organized into compartments containing B cells, T cells, and other accessory cells of the adaptive immune system.These structures are an essential part of the lymphatic system.