There is a gradient of solutes in the interstitial fluid from the renal cortex through the medulla, known as the medullary osmotic gradient. The juxtamedullary nephrons establish and maintain this gradient using countercurrent mechanisms with loops extending deep into the medulla. These nephrons also use countercurrent mechanisms to regulate urine volume and concentration. The interaction between the descending and ascending limbs of the nephron loop creates an osmotic gradient through countercurrent multiplication. This gradient facilitates water reabsorption from the tubular fluid in the descending limb and the active transport of solutes like sodium in the ascending limb.

In contrast, countercurrent exchange occurs in the limbs of the vasa recta capillaries surrounding the nephron loop. These capillaries exchange solutes and water between the blood and the interstitial fluid, maintaining the osmotic gradient.

Dehydration induces the posterior pituitary to release antidiuretic hormone (ADH), resulting in the reabsorption of water in the late distal tubule and collecting ducts. As a result, urine is produced in small volumes, about four times more concentrated than blood plasma.

Do Capítulo 29:

article

Now Playing

29.18 : Formation of Concentrated Urine

The Urinary System

497 Visualizações

article

29.1 : Introduction to Urinary System

The Urinary System

582 Visualizações

article

29.2 : External Anatomy of the Kidney

The Urinary System

282 Visualizações

article

29.3 : Internal Anatomy of the Kidney

The Urinary System

352 Visualizações

article

29.4 : Blood and Nerve Supply to the Kidney

The Urinary System

200 Visualizações

article

29.5 : Nephrons

The Urinary System

610 Visualizações

article

29.6 : Renal Corpuscle

The Urinary System

362 Visualizações

article

29.7 : Renal Tubule and Collecting Duct

The Urinary System

308 Visualizações

article

29.8 : Physiology of Urine Formation

The Urinary System

750 Visualizações

article

29.9 : Glomerular Filtration

The Urinary System

377 Visualizações

article

29.10 : Glomerular Filtration: Net Filtration Pressure

The Urinary System

377 Visualizações

article

29.11 : Glomerular Filtration Rate and its Regulation

The Urinary System

883 Visualizações

article

29.12 : Tubular Reabsorption and Secretion

The Urinary System

151 Visualizações

article

29.13 : Reabsorption and Secretion in the PCT

The Urinary System

296 Visualizações

article

29.14 : Reabsorption and Secretion in the Loop of Henle

The Urinary System

304 Visualizações

See More

JoVE Logo

Privacidade

Termos de uso

Políticas

Pesquisa

Educação

SOBRE A JoVE

Copyright © 2025 MyJoVE Corporation. Todos os direitos reservados