During urine formation filtrate moves 4 times between cortex and medulla

Filterate movement in the kidney
The filterate in the kidney moves multiple times between the cortex and medulla during the process of urine formation.

Initial filtration in the glomerulus
- The initial step of urine formation occurs in the glomerulus, a network of capillaries located in the renal cortex.
- Blood is filtered in the glomerulus to form the filterate, which contains water, ions, glucose, and waste products.

Reabsorption in the proximal convoluted tubule
- The filterate moves from the glomerulus to the proximal convoluted tubule, located in the renal cortex.
- In the proximal convoluted tubule, essential substances like glucose, amino acids, and ions are reabsorbed back into the bloodstream.

Loop of Henle and the medullary region
- The filterate then moves to the loop of Henle, which extends into the medulla of the kidney.
- The loop of Henle plays a crucial role in concentrating the urine by creating a concentration gradient in the medullary region.

Collecting duct in the cortex
- Finally, the filterate moves to the collecting duct, which is located in the renal cortex.
- The collecting duct further concentrates the urine by reabsorbing water back into the bloodstream, depending on the body's hydration status.

Summary
The filterate moves between the cortex and medulla multiple times to undergo filtration, reabsorption, and concentration processes essential for the formation of urine. This intricate process ensures that the body maintains proper fluid balance and eliminates waste products effectively.