Final answer:
Lymphedema is the accumulation of interstitial fluid in tissues caused by a failure of the lymphatic system to drain excess fluid, leading to swelling and possible medical issues.
Step-by-step explanation:
Lymphedema Defined
Lymphedema is the accumulation of interstitial fluid in tissue that occurs when the lymphatic system is impaired. In a healthy system, about 20 liters of plasma is released into the interstitial space of the tissues each day due to capillary filtration, and the lymphatic system is responsible for draining excess fluid, roughly three liters, and returning it to the bloodstream. However, if the lymphatic system is damaged or blocked, this protein-rich interstitial fluid begins to accumulate in the tissue spaces, leading to the swelling known as lymphedema, which can have significant medical consequences.
Edema vs. Lymphedema
While edema refers generally to the accumulation of excess water in the tissues, often due to water leakage from blood capillaries and resulting in swollen limbs, tight skin, and the potential for 'pitting,' lymphedema specifically results from a failure of the lymphatic system to perform its function of fluid balance, leading to systemic or localized fluid retention.