Urinary System: Structure, Function and Osmoregulatory Function of Kidney
Urinary System of Humans
Structure of Kidney
The longitudinal segment of the kidney indicates two regions. The renal cortex is the outer/external piece of the kidney and it is dark red in color. The renal medulla is the internal/interior piece of the kidney and is light red in color. The renal medulla consists of several cone-shaped areas known as renal pyramids. Renal pyramids venture into a funnel-shaped pit known as the renal pelvis, which is the base of the ureter.
Function of Kidney
i) Pressure Filtration
ii) Selective Re-absorption
In this stage, about 99% of the glomerular filtrate is reabsorbed into the blood capillaries surrounding the renal tubule. It occurs via osmosis diffusion and dynamic transport. Some water and most of the glucose is reabsorbed from the proximal tangled tubule. Here, salts are reabsorbed by dynamic transport, and after that water follows by osmosis. The dropping limb of the circle of Henle permits the reabsorption of water while the ascending limb of Loop of Henle allows the reabsorption of salts. The distal tangled tubule again permits the reabsorption of water into the blood.
iii) Tubular secretion
After the above-mentioned stages, the filtrate present in renal tubules is known as urine. It moves into gathering ducts and then into the pelvis.