Lymphology Association of North America (LANA) Practice Exam

What is the main purpose of the lymphatic system?

1. To transport oxygen to tissues

2. To support digestion

3. To collect and return interstitial fluid to the bloodstream

4. To produce hormones

The correct answer is: To collect and return interstitial fluid to the bloodstream

The primary purpose of the lymphatic system is to collect and return interstitial fluid to the bloodstream. This system plays a crucial role in maintaining fluid balance within the body. As blood circulates, some plasma escapes into the tissues, leading to the formation of interstitial fluid. The lymphatic vessels collect this excess fluid and transport it back to the blood, thus preventing swelling and ensuring that the body's tissues are properly hydrated. Additionally, the lymphatic system is involved in transporting white blood cells and waste products, playing an essential role in the immune response and helping to filter out harmful substances. This fluid not only contributes to the overall fluid homeostasis but also aids in the absorption of dietary fats and fat-soluble vitamins from the digestive system through specialized lymph vessels known as lacteals. In contrast, the other functions listed—transporting oxygen, supporting digestion, and producing hormones—are not the primary roles of the lymphatic system. While oxygen transport is a function of the circulatory system, digestion is supported by other systems such as the gastrointestinal tract, and hormone production is primarily associated with the endocrine system. Therefore, the lymphatic system is specifically vital for maintaining fluid balance and immune function in the body.