Nephron Function and Lymphatic System: Roles and Processes

Operation of the Nephron

Filtration of blood occurs as it passes through the glomerulus. Substances pass into the renal tubule, small molecules but not large molecules or cells. This process forms the primary urine.

Reabsorption of useful substances, such as glucose, amino acids, and over 90% of the water, takes place along the renal tubule.

Secretion of noxious substances, such as urea or some mineral salts, from the capillaries into the renal tubule, continues along the entire duct, so that inside it, concentrated urine is formed. This is drained into a collecting duct, common to many nephrons, which flows into the renal pelvis. As a result of the process, blood from the kidneys, via the renal veins, is cleansed of waste products.

Average Domestic

Interstitial fluid is formed when blood is in the capillaries. This liquid lacks red blood cells, as they cannot pass through the walls of the capillaries. It is the fluid that bathes the cells, allowing them to take in nutrients and dump their waste.

Lymph is formed from interstitial fluid and drains into collector tubes through which it circulates, and which form the body's second circulation system, the lymphatic system.

Lymphatic System

Lymph vessels are small-diameter collector pipes that have a large number of valves that prevent the retreat of the lymph, and whose terminus is a closed sac.

Lymph nodes, interspersed along the route of the lymphatic vessels, are involved in defending the body. They produce lymphocytes, blood cells for defense, and store macrophages, which phagocytize pathogenic microorganisms and malignant cells. They are distributed throughout the body, being very abundant in the armpits, neck, and groin.

Collector terminals: The thoracic duct receives lymph from three-quarters of the body and lymphatic dilation stems from a tank called Pecquet's cystern. The right lymphatic duct collects lymph from the right upper limb. Lymph returns to the venous system from the thoracic duct and right lymphatic duct to the left and right subclavian veins, respectively.

Roles of the Lymphatic System

• Maintain liquid balance in the internal environment.
• Provide a circulatory circuit.
• Take part in defending the body.