Answer:
The 3 main function of kidney are ultrafiltration, reabsorption, and excretion.
Explanation:
The 3 functions of the kidney are ultrafiltration, reabsorption, and excretion. The kidney is the excretory organ of the body and maintains the osmotic balance. The nephrons are the unit of the kidney. They are smaller tubules and have 2 parts - cortical nephrons and juxtamedullary nephrons. The cortical nephrons present in the cortex part and the juxtamedullary nephrons are present in the medulla of the kidney. Nephrons have a different section that takes part in the urine formation. These are - glomerulus surrounded by bowman's capsule, PCT, Loop of Henle's, DCT, and Collecting tubule. In the glomerulus the afferent and efferent arterioles are present. The afferent arterioles carry oxygenates blood along with glucose, amino acids, urea, salts into the kidney. Here due to more pressure, the blood diffuses those materials into kidneys. The entire nephron is surrounded by blood vessels. Thus the materials carried by blood filtered into the kidney. These filtered materials come to PCT / proximal convoluted tubule. Here 80 % absorption occurs. All the essential materials again reabsorbed by the blood vessels to the tissues. Then the rest of the salt and water enters into descending limb of the loop of Henle. Here the water is reabsorbed again to the bloodstreams. The remaining water and salts go to DCT through the ascending limb of LH. In the distal convoluted tubule less absorption occurs. Here urea, water, salts are stored and go down to collecting duct. These water and urea is the end product after ultrafiltration and selective reabsorption. These are stored again in the urethra and when it fills, pass out in the form of urine. Besides this kidney secretes ADH, renin, angiostatin hormone which helps in maintaining the homeostasis of the body.
