Kokko and Rector Model

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The Kokko and Rector model is a theory explaining the mechanism of generation of a gradient in the inner medulla of the kidney. Unlike earlier theories explaining the mechanism using counter current mechanism (as is the case in the outer medulla), the driving force for salt reabsorption is stated to be urea accumulation. It has been proved that counter current mechanism cannot be the case in the inner medulla, since there are no salt pumps, and the cell membrane is too permeable to salt.[ clarification needed ]

Kidney internal organ in most animals, including vertebrates and some invertebrates

The kidneys are two bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about 11 centimetres (4.3 in) in length. They receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder.

Cell membrane Biological membrane that separates the interior of a cell from its outside environment

The cell membrane is a biological membrane that separates the interior of all cells from the outside environment which protects the cell from its environment consisting of a lipid bilayer with embedded proteins. The cell membrane controls the movement of substances in and out of cells and organelles. In this way, it is selectively permeable to ions and organic molecules. In addition, cell membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity and cell signalling and serve as the attachment surface for several extracellular structures, including the cell wall, the carbohydrate layer called the glycocalyx, and the intracellular network of protein fibers called the cytoskeleton. In the field of synthetic biology, cell membranes can be artificially reassembled.

Semipermeable membrane membrane which will allow certain molecules or ions to pass through it by diffusion

A semipermeable membrane is a type of biological or synthetic, polymeric membrane that will allow certain molecules or ions to pass through it by diffusion—or occasionally by more specialized processes of facilitated diffusion, passive transport or active transport. The rate of passage depends on the pressure, concentration, and temperature of the molecules or solutes on either side, as well as the permeability of the membrane to each solute. Depending on the membrane and the solute, permeability may depend on solute size, solubility, properties, or chemistry. How the membrane is constructed to be selective in its permeability will determine the rate and the permeability. Many natural and synthetic materials thicker than a membrane are also semipermeable. One example of this is the thin film on the inside of the egg.

Contents

History

It has been proposed by JP Kokko and FC Rector Jr in 1972. [1]

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References

  1. Kokko, Juha P; Rector Jr, Floyd C (1972). "Countercurrent multiplication system without active transport in inner medulla". Kidney International. 2 (4): 214–23. doi:10.1038/ki.1972.97. PMID   4657922.

Further reading

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