Editing Loop of Henle (section)

==Structure==
The loop of Henle can be divided into four parts:
*Thin [[descending limb of loop of Henle]]
:The thin descending limb has low permeability to ions and [[urea]] while being highly permeable to water. The loop has a sharp bend in the [[renal medulla]] going from descending to ascending thin limb.
*[[Thin ascending limb of loop of Henle]]
:The thin ascending limb is impermeable to water, but it is permeable to ions.
*[[Ascending limb of loop of Henle]]
:Sodium (Na<sup>+</sup>), [[potassium]] (K<sup>+</sup>) and [[chloride]] (Cl<sup>−</sup>) ions are reabsorbed from the urine by [[secondary active transport]] by a [[Na–K–Cl cotransporter]] (NKCC2).  The electrical and concentration gradient drives more reabsorption of Na<sup>+</sup>, as well as other [[cation]]s such as [[magnesium]] (Mg<sup>2+</sup>) and [[calcium]] (Ca<sup>2+</sup>).
*Cortical thick ascending limb
:The [[renal cortex|cortical]] thick ascending limb drains urine into the [[distal convoluted tubule]].<ref name=Kaplan.Physio />
The tissue type of the loop is simple [[squamous epithelium]]. The "thick" and "thin" terminology does not refer to the size of the lumen, but to the size of the epithelial cells.<ref>Human Anatomy 7th edition (p.705)</ref> The loop is also sometimes called the nephron loop.{{Citation needed|date=July 2023}}

===Blood supply===
[[File:Countercurrentmultiplier.jpg|thumb|Counter current multiplier diagram]]
The loop of Henle is supplied by blood in a series of straight capillaries descending from the cortical efferent arterioles. These capillaries (called the [[Straight arterioles of kidney|vasa recta]]; ''recta'' is from the [[Latin language|Latin]] for "straight") also have a [[countercurrent exchange#Countercurrent multiplier|countercurrent multiplier]] mechanism that prevents washout of solutes from the medulla, thereby maintaining the medullary concentration. As water is osmotically driven from the descending limb into the [[interstitium]], it readily enters the capillaries. The low bloodflow through the vasa recta allows time for osmotic equilibration, and can be altered by changing the resistance of the vessels' efferent arterioles.{{Citation needed|date=June 2011}}

As well, blood in the vasa recta still has large proteins and ions which were not filtered through the glomerulus. This provides an [[oncotic pressure]] for ions to enter the vasa recta from the interstitium.{{Citation needed|date=June 2011}}

The main function of the loop of Henle is to absorb water and sodium chloride from the filtride which preserving water and produces highly concentrated urine.<ref>{{Cite web |last=MD |first=Dr Liji Thomas |date=2016-07-25 |title=The Loop of Henle |url=https://www.news-medical.net/health/The-Loop-of-Henle.aspx#:~:text=Its%20main%20function%20is%20to,organism,%20producing%20highly%20concentrated%20urine. |access-date=2025-03-05 |website=News-Medical |language=en}}</ref>{{Citation needed|date=June 2011}}