Juxtamedullary nephron
Encyclopedia
A juxtamedullary nephron is a type of nephron
, found only in birds and mammals and not in other vertebrates. The "medullary" is referring to the renal medulla
, while the "juxta", (Latin: near), refers to the relative position of the renal corpuscle
, which in these nephrons is near the medulla. In other words, a "juxtamedullary nephron" is one where the renal corpuscle is close to the medulla, and the proximal convoluted tubule and its associated loop of Henle
occur at a deep position compared to most other nephrons.
This type of nephron is relatively rare, and only comprise 20-30% of the nephrons in the human kidney. However, in most depictions of the nephron, it is a juxtamedullary nephron which is depicted. The greater gradient in the deep medulla make this type of nephron do more "work" than more shallow nephrons, and their vertical nature makes them easier to illustrate. It is these nephrons which are responsible for the development of the osmotic gradients in the renal medulla, which are used to concentrate urine.
Nephron
The renal tubule is the portion of the nephron containing the tubular fluid filtered through the glomerulus. After passing through the renal tubule, the filtrate continues to the collecting duct system, which is not part of the nephron....
, found only in birds and mammals and not in other vertebrates. The "medullary" is referring to the renal medulla
Renal medulla
The renal medulla is the innermost part of the kidney. The renal medulla is split up into a number of sections, known as the renal pyramids. Blood enters into the kidney via the renal artery, which then splits up to form the arcuate arterioles. The arcuate arterioles each in turn branch into...
, while the "juxta", (Latin: near), refers to the relative position of the renal corpuscle
Renal corpuscle
In the kidney, a renal corpuscle is the initial blood-filtering component of a nephron. It consists of two structures: a glomerulus and a Bowman's capsule. The glomerulus is a small tuft of capillaries containing two cell types. Endothelial cells, which have large fenestrae, are not covered by...
, which in these nephrons is near the medulla. In other words, a "juxtamedullary nephron" is one where the renal corpuscle is close to the medulla, and the proximal convoluted tubule and its associated loop of Henle
Loop of Henle
In the kidney, the loop of Henle is the portion of a nephron that leads from the proximal convoluted tubule to the distal convoluted tubule. Named after its discoverer F. G. J...
occur at a deep position compared to most other nephrons.
This type of nephron is relatively rare, and only comprise 20-30% of the nephrons in the human kidney. However, in most depictions of the nephron, it is a juxtamedullary nephron which is depicted. The greater gradient in the deep medulla make this type of nephron do more "work" than more shallow nephrons, and their vertical nature makes them easier to illustrate. It is these nephrons which are responsible for the development of the osmotic gradients in the renal medulla, which are used to concentrate urine.
