Renal corpuscle is the initial component of the nephron filtration, consisting of two structures, one glomerulus and Bowman’s capsule. Glomerulus is a small intertwined group of fine blood vessels that receives blood from the renal circulation. The blood pressure in the glomerulus provides the driving force of solutes that seep into the space made by Bowman’s capsule. Damage to the glomerulus may result in a condition known as glomerulonephritis. Bowman’s capsule is a double cup-shaped membrane surrounding the glomerulus. Also known as the glomerular capsule, Bowman’s capsule is composed of a thin layer made of visceral specialized cells called podocytes and parietal outer layer made of simple squamous epithelium.
Renal tubules are the tubes that are based on the Bowman’s capsule in the cortex, the loop through the renal medulla and then back to the cortex and connected to the pipeline system of collection. Each renal tubule is divided into a proximal tubule, loop of Henle and distal convoluted tubule. The proximal tubule has microvillus a brush border, which increases the surface area for absorption.
The nephrons are classified into two general types: cortical nephrons and juxtamedullary nephrons, based on the location of the renal corpuscles associated with them. The renal corpuscles of cortical nephrons are present in the renal cortex surface, while the juxtamedullary nephrons are close to the renal medulla. Any damage to these nephrons can affect its function and result in serious kidney disease. Now that you know what the nephrons and what is composed, let’s move to the function of nephrons.
Function of the nephron
The function of nephrons in the kidney is mainly concerned with filtration, reabsorption and secretion of various solutes, carbohydrates and glutamate. The blood entering the glomerulus is separated by space in the Bowman’s capsule of two layers of cells and a basement membrane. The basement membrane is composed of collagen fibers and glycoproteins. The mesh like structure of this collagen fiber filters blood through a process known as ultrafiltration. Most small molecules in the blood can pass through the membrane, however, it prevents large proteins such as blood cells and molecules pass through them. Approximately 70 percent of water and solutes are removed from blood plasma as it passes through the glomeruli. Many useful substances such as glucose and amino acids are also filtered by this process. Now, these molecules are absorbed back into the body by a process known as selective reabsorption to maintain electrolyte levels in the body.
The filtrate entering the proximal tubule of the nephron and is reabsorbed into the peritubular capillaries. All essential substances such as glucose, vitamins, amino acids and ions are actively transported back into the blood. Microvillus provides a large surface and thus facilitate effective absorption. Now, the solute concentration of the blood in the capillaries surrounding the nephron increases as these substances are added back to them. To balance electrolyte levels, a large amount of water flows back to the blood in the proximal tubule by a process known as osmosis.
The function of the loop of Henle is to concentrate the salts that are excreted in urine. An area of high solute concentration in the bone is created. Members of Henle are permeable to certain ions and solutes and water is reabsorbed in the collecting ducts which pass through this area. Ramus is more permeable to the salts, compared to water and active absorption of salts causes more water to be pushed through the downstream portion, resulting in the formation of concentrated urine. Pour in the distal convoluted tubule, which maintains the pH levels in urine and blood. The fluid is passed into the collecting duct where the ultrafiltration is carried out again. It then passes into the ureters and bladder to be removed from the body.
This was all about the function of nephrons in the kidney. These small tubes are able to perform complex functions of the body to keep it running smoothly. Improper operation or damage to any of these structures can lead to various kidney diseases.