Describe the structure and function of nephron

Nephrons: The Functional Units of the Kidney. Nephrons take a simple filtrate of the blood and modify it into urine. Nephrons are the “functional units” of the kidney; they cleanse the blood and balance the constituents of the circulation. Each kidney is made up of over one million nephrons that dot the renal cortex, giving it a granular appearance when sectioned sagittally. Many changes take place in the different parts of the nephron before urine is created for disposal. The term forming urine will be used hereafter to describe the filtrate as it is modified into true urine. The principle task of the nephron population is to balance the plasma to homeostatic set points and excrete potential toxins in the urine. They do this by accomplishing three principle functions—filtration, reabsorption, and secretion. They also have additional secondary functions that exert control in three areas: blood pressure (via production of renin), red blood cell production (via the hormone EPO), and calcium absorption (via conversion of calcidiol into calcitriol, the active form of vitamin D). Tubular parts of a Nephron – converts the filtrate into urine • The Bowman’s capsule / Glomerular capsule: The Bowman’s capsule (also called the glomerular capsule), is the beginning of a nephron. It surrounds the glomerulus. It is a double walled cup, It is composed of inner visceral and outer parietal layers. Parietal (outer) layer of glomerular capsule is simple squamous epithelium. Visceral (inner)...

Learning Objectives • Describe the structure and function of each region of the mammalian nephron (glomerulus, Bowman’s capsule, proximal convoluted tubule, Loop of Henle, distal convoluted tubule, and collecting duct) • Recognize the roles of active/passive transport, osmotic gradients, and countercurrent exchange in nephron function • Explain integrated hormonal regulation of water/ion regulation by the mammalian kidney The information below was adapted from Although the kidneys are the major osmoregulatory organ, the skin and lungs also play a role in the process. Water and electrolytes are lost through sweat glands in the skin, which helps moisturize and cool the skin surface, while the lungs expel a small amount of water in the form of mucous secretions and via evaporation of water vapor. Kidneys: The Main Osmoregulatory Organ The kidneys, in mammals, are a pair of bean-shaped structures that are located just below and posterior to the liver in the peritoneal cavity. The adrenal glands sit on top of each kidney and are also called the suprarenal glands. Kidneys filter blood and purify it. All the blood in the human body is filtered many times a day by the kidneys; these organs use up almost 25 percent of the oxygen absorbed through the lungs to perform this function. Oxygen allows the kidney cells to efficiently manufacture chemical energy in the form of ATP through aerobic respiration. The filtrate coming out of the kidneys is called urine. Kidneys filter the blood, ...

2. The Juxta-Medullary Nephrons These make up about 15% of the total number and are found in the inner third of the cortex. This nephron is large and works only under conditions of stress. What is the Structure of Nephron? There are 1.3 million nephrons in each human kidney. Here we describe the structure of nephron with the help of diagrams now. The nephron comprises three parts., 1.Glomerulus The glomerulus has a diameter of about 200 m. It is formed by the invagination of a tuft of capillaries into a dilated blood vessel. At the blind end of the nephron, the capillaries are supplied by an “afferent arteriole” and drained by a smaller “efferent arteriole.” The afferent arteriole breaks up into about fifty capillary loops and forms the glomerular tuft, which lies within Bowman’s capsule, a double-walled epithelial sac. Each nephron begins with a tuft of 6-8 renal blood capillaries that are probed into the end of a tubule. This structure is named “Glomerulus.” Mesangial cells are shared by two capillaries that are next to each other. In these places, the base membrane forms a sheath that both capillaries share. The cells are contractile and play a role in regulating “glomerular filtration.” They also secrete various substances, take up “immune complexes,” and are involved in the production of glomerular disease. The glomerular membrane permits the free passage of neutral substances up to 4 nm in diameter and almost excludes those with diameters greater than 8 nm. 2.Bowman’...

Nephrons: • The nephron is the functional unit of the kidney. • It is composed of a renal corpuscle and a renal tubule. Structure of nephrons: • Nephrons are basic filtering units of kidneys. • Each kidney possesses a large number of nephrons (approx. 1-1.5 million). • The components of the nephron: • Glomerulus, • Bowman's capsule • Long renal tubule. Functions of nephron: • The blood enters the kidney through the renal artery (which branches into capillaries associated with the glomerulus). • Water and solute are transferred to Bowman's capsule. • In the proximal convoluted tubule, glucose and salts are selectively reabsorbed. • Now filtrate moves down into the loop of Henle. • And then move upward to the distal convoluted tubule and finally into the collecting duct.