Lymphology Association of North America (LANA) Practice Exam

Which of the following is NOT a function of the lymphatic system?

1. Return of water and protein to the cardiovascular system

2. Absorption of fat and fat-soluble vitamins

3. Immunological function

4. Return of water and protein to the interstitium

The correct answer is: Return of water and protein to the interstitium

The lymphatic system serves several critical functions in maintaining overall fluid balance, nutrient absorption, and immune defense within the body. While it is responsible for returning excess fluid and proteins from interstitial spaces back to the cardiovascular system, the statement that the lymphatic system functions to return water and protein to the interstitium is not accurate. The primary role of the lymphatic system is to drain excess interstitial fluid, thereby preventing edema, and to return that fluid to the bloodstream. This process actually helps maintain homeostasis within tissue environments. The system also plays a vital role in absorbing dietary fats and fat-soluble vitamins through specialized lymph vessels known as lacteals located in the intestinal villi. Additionally, it is integral to the body’s immunological functions, as it transports immune cells and facilitates the removal of pathogens. Thus, the assertion that the lymphatic system returns water and protein to the interstitium misses the mark, as its function primarily involves returning this fluid to the cardiovascular system, making it the correct answer to identify as not a function of the lymphatic system.