Why is the nephron loop called the countercurrent multiplier?
Because the blood flow through these capillaries is very slow, any solutes that are reabsorbed into the bloodstream have time to diffuse back into the interstitial fluid, which maintains the solute concentration gradient in the medulla. This passive process is known as countercurrent exchange.
Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some component, between two flowing bodies flowing in opposite directions to each other.
- countercurrent exchange. a biological mechanism designed to enable maximum exchange between two fluids. The mechanism's effect is dependent on the two fluids flowing in opposite directions, and having a concentration gradient between them.
- Peritubular capillaries surround the proximal and distal tubules, as well as the loop of Henle, where they are known as vasa recta. This blood leaves the glomerulus via the efferent arteriole, which supplies the peritubular capillaries.
- The first part of the nephron that is responsible for water reabsorption is the proximal convoluted tubule. Filtered fluid enters the proximal tubule from Bowman's capsule. Many substances that the body needs, which may have been filtered out of the blood at the glomerulus, are reabsorbed into the body in this segment.
A system in which energy is used to transport material across a membrane separating two countercurrent multiplier tubes connected at one end to form a hairpin shape; by this means a concentration can be achieved in the fluid in the hairpin bend, relative to the inflow and outflow fluids, which is much greater than the
- Countercurrent multiplication in the kidneys is the process of using energy to generate an osmotic gradient that enables you to reabsorb water from the tubular fluid and produce concentrated urine.
- Both penicillin G and carbenicillin were secreted by the proximal tubule of the rat nephron, but the latter was secreted at a lower rate than the former. A significant fraction of penicillin G was reabsorbed from the collecting ducts under conditions of maximal antidiuresis.
- Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some component, between two flowing bodies flowing in opposite directions to each other.
Fish also have an efficient transport system within the lamellae which maintains the concentration gradient across the lamellae. The arrangement of water flowing past the gills in the opposite direction to the blood (called countercurrent flow) means that they can extract oxygen at 3 times the rate a human can.
- Hemoglobin: The protein inside red blood cells (a) that carries oxygen to cells and carbon dioxide to the lungs is hemoglobin (b). Hemoglobin is made up of four symmetrical subunits and four heme groups. Iron associated with the heme binds oxygen.
- Gills are feathery organs full of blood vessels. A fish breathes by taking water into its mouth and forcing it out through the gill passages. As water passes over the thin walls of the gills, dissolved oxygen moves into the blood and travels to the fish's cells.
- Gills take oxygen out of the water and let water carry away carbon dioxide. Fish force water through their gills, where it flows past lots of tiny blood vessels. Oxygen seeps through the walls of those vessels into the blood, and carbon dioxide seeps out.
Updated: 26th November 2019