Final answer:
Lymph flow is driven by the pressure differential caused by fluid leak from blood capillaries into the interstitial space, moving through lymphatic vessels aided by their contractions and skeletal muscle movements.
Step-by-step explanation:
The primary reason for the flow of lymph is due to the pressure differential created by the leakage of fluid from the blood capillaries into the interstitial spaces.
As fluid accumulates in the interstitial space, it becomes what is known as lymph. The lymph then enters tiny lymphatic capillaries and is transported through the lymphatic vessel network to eventually empty into the venous bloodstream at two major veins located in the upper chest region.
Two contributing factors to the movement of lymph through the lymphatic vessels are:
The contractions of the lymphatic vessels themselves.
The external forces applied by skeletal muscle contractions during body movements, which help push the lymph through the vessels.
Additionally, lymphatic vessels contain numerous valves that ensure lymph flows in one direction, preventing backflow. The movement of lymph is crucial as it helps to filter out pathogens at lymph nodes and supports overall bodily fluid balance and immune defense mechanisms.