Final answer:
The lymphatic system is responsible for returning 10-15% of the capillary filtrate to the blood, acting as a critical component for maintaining fluid balance and supporting the immune system by transporting lymph, which is essentially recycled blood plasma.
Step-by-step explanation:
10-15% of the capillary filtrate is returned to blood not directly but rather via the lymphatic system. The lymphatic system plays a critical role in maintaining fluid balance within the body by absorbing excess fluid, including proteins and waste products, which accumulates in the space between cells. This fluid is then transported through the lymphatic vessels to be eventually returned to the bloodstream. The capillaries of the lymphatic system are equipped with valves that ensure unidirectional flow, leading the fluid through larger lymphatic vessels and eventually draining it into the subclavian veins in the neck.
An essential function of the lymphatic system is the return of fluid, known as lymph, to the blood, effectively recycling the blood plasma. The process helps to prevent edema and supports the immune system by transporting lymphocytes. By returning filtrate from the capillaries to the venous blood, it contributes to the maintenance of blood volume and pressure, completing the circulatory cycle.