describe the main structures of the nephron and their functions
Nephron The nephron (from Greek νεφρός – nephros, meaning "kidney") is the microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and an encompassing Bowman's capsule. The renal tubule extends from the capsule. The capsule and tubule are connected and are composed of epithelial cells with a lumen. A healthy adult has 0.8 to 1.5 million nephrons in each kidney. Blood is filtered as it passes through three layers: the endothelial cells of the capillary wall, its basement membrane, and between the foot processes of the podocytes of the lining of the capsule. The tubule has adjacent peritubular capillaries that run between the descending and ascending portions of the tubule. As the fluid from the capsule flows down into the tubule, it is processed by the epithelial cells lining the tubule: water is reabsorbed and substances are exchanged (some are added, others are removed); first with the interstitial fluid outside the tubules, and then into the plasma in the adjacent peritubular capillaries through the endothelial cells lining that capillary. This process regulates the volume of body fluid as well as levels of many body substances. At the end of the tubule, the remaining fluid—urine—exits: it is composed of water, metabolic waste, and toxins.
Cellular waste product H2O also diffuses out of the cell into the blood stream, from where it is excreted in the form of perspiration, water vapor in breath, or urine from the kidneys. Water, along with some dissolved solutes, are removed from blood circulation in the nephrons of the kidney and eventually excreted as urine.[12]
Cilium The functioning of motile cilia is strongly dependent on the maintenance of optimal levels of fluid bathing the cilia. Epithelial sodium channels ENaC that are specifically expressed along the entire length of cilia apparently serve as sensors that regulate fluid level surrounding the cilia.[12][14]
Blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells.[1]