Thin ascending limb of loop of Henle
Encyclopedia
The thin ascending limb of loop of Henle is a sub-portion of the loop of Henle
in the juxtamedullary nephron
of the kidney
. The thin ascending limb is impermeable to water
, and is also permeable to ions in particular Na and Cl. As filtrate passes up through this limb, the solute concentration of the surrounding medulla
decreases because more water is leaking into surrounding plasma, and increases the solute concentration within the loop of Henle. However, because this segment is also permeable to solutes, ions and other small particles can pass through the limb and enter the extracellular fluid (ECF) which causes the solute concentration of the ECF to rise, and thus causes the solute concentration within the loop of Henle to decrease. How the mechanism of the ascending loop of Henle decides how much water and/or solutes to reabsorb depends on the state of the body at the time. These molecules will flow down their concentration gradient. For example, if the body is dehydrated, more water will flow out of the loop of Henle and be reabsorbed back into the blood. (Information from Marieb, E. N. 2010. Human Anatomy and Physiology, 8th Ed. Pearson Benjamin Cummings.)
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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...
in the juxtamedullary nephron
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....
of the kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
. The thin ascending limb is impermeable to water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
, and is also permeable to ions in particular Na and Cl. As filtrate passes up through this limb, the solute concentration of the surrounding medulla
Medulla
Medulla refers to the middle of something and derives from the Latin word for marrow. Its anatomical uses include:* Medulla oblongata, a part of the brain stem* Renal medulla, a part of the kidney* Adrenal medulla, a part of the adrenal gland...
decreases because more water is leaking into surrounding plasma, and increases the solute concentration within the loop of Henle. However, because this segment is also permeable to solutes, ions and other small particles can pass through the limb and enter the extracellular fluid (ECF) which causes the solute concentration of the ECF to rise, and thus causes the solute concentration within the loop of Henle to decrease. How the mechanism of the ascending loop of Henle decides how much water and/or solutes to reabsorb depends on the state of the body at the time. These molecules will flow down their concentration gradient. For example, if the body is dehydrated, more water will flow out of the loop of Henle and be reabsorbed back into the blood. (Information from Marieb, E. N. 2010. Human Anatomy and Physiology, 8th Ed. Pearson Benjamin Cummings.)
Histology
As in the descending limb, the epithelium is simple squamous epitheliumSimple squamous epithelium
A simple squamous epithelium is a single layer of flat cells in contact with the basal lamina of the epithelium. This type of epithelium is often permeable and occurs where small molecules pass quickly through membranes via filtration or diffusion...
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