What is the primary function of lymph nodes?

The primary function of lymph nodes is to filter lymph. Lymph nodes are integral components of the lymphatic system, which is responsible for maintaining fluid balance, filtering out pathogens, and supporting immune function. Lymph, a clear fluid that circulates through the lymphatic system, contains white blood cells that help fight infections.

As lymph passes through the lymph nodes, these nodes filter out harmful substances such as bacteria, viruses, and other foreign materials. They trap these pathogens and contain immune cells, particularly lymphocytes, which respond to infections by initiating immune responses. This filtering process is crucial for the body's defense mechanisms, helping to prevent the spread of infections throughout the body.

In contrast, the other functions listed do not pertain to lymph nodes. The transportation of blood is primarily the function of blood vessels, like arteries and veins. Hormonal regulation is managed by endocrine glands, and energy production occurs mainly within the body's cells through metabolic processes. Therefore, the role of lymph nodes in filtering lymph highlights their importance in maintaining the body’s immune health.