About counter current mechanism

Click For Summary
SUMMARY

The countercurrent mechanism in the renal system is crucial for urine concentration, primarily occurring in the medullary collecting tubules. Water exits these tubules due to osmotic pressure, as the medulla is hyperosmotic. The vasa recta, which also traverses the hyperosmotic medulla, absorbs water through a balance of osmotic and hydrostatic pressures. The hydrostatic pressure from the bloodstream initially pushes water into the Bowman's capsule, but as blood moves away from the glomerulus, osmotic pressure becomes the dominant force, facilitating water reabsorption into the peritubular capillaries.

PREREQUISITES
  • Understanding of renal physiology and nephron structure
  • Knowledge of osmotic and hydrostatic pressure principles
  • Familiarity with the role of the glomerulus and Bowman's capsule
  • Basic concepts of urine formation and concentration mechanisms
NEXT STEPS
  • Research the role of the nephron in urine concentration
  • Study the mechanisms of osmotic and hydrostatic pressure in renal function
  • Explore the anatomy and function of the vasa recta
  • Learn about the effects of various hormones on renal water reabsorption
USEFUL FOR

Students of renal physiology, medical professionals, and anyone interested in the mechanisms of urine concentration and kidney function.

keep@science
Messages
8
Reaction score
0
As medulla is hyperosmotic with respect to medullary collecting tubules (I.e. main site for water absorption )water flows out of the collecting tubules and urine get concentrated ...But how it enters vasa
recta since vasa recta is also going through same hyperosmotic medulla ,how it absorbs The water ?
 
Biology news on Phys.org
This isn't my area of expertise, so take this with a grain of salt, but...

It's not just osmotic pressure that forces water out of the glomerulus and into the Bowman's capsule. It's also hydrostatic pressure (basically, plain old blood pressure). So the total (osmotic + hydrostatic) pressure gradient in the renal corpuscle pushes water and small molecules out of the bloodstream and into the urinary ultrafiltrate.

However, once the filtered blood passes out of the glomerulus, the hydrostatic pressure in the bloodstream drops and the osmotic pressure between the peritubular capillaries and the collecting tubules dominates the net direction of water flow. Since the blood in the peritubular capillaries is hyperosmotic compared with the collecting tubules, water flows back into the bloodstream, concentrating the urine.
 
  • Like
Likes jim mcnamara and berkeman
As child, before I got my first X-ray, I used to fantasize that I might have a mirror image anatomy - my heart on the right, my appendix on the right. Why not? (Caveat: I'm not talking about sci-fi molecular-level mirroring. We're not talking starvation because I couldn't process certain proteins, etc.) I'm simpy tlakng about, when a normal zygote divides, it technically has two options which way to form. Oen would expcet a 50:50 split. But we all have our heart on the left and our...

Similar threads

Replies
2
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 12 ·
Replies
12
Views
3K
Replies
5
Views
3K
Replies
1
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 40 ·
2
Replies
40
Views
3K
Replies
3
Views
4K
  • · Replies 17 ·
Replies
17
Views
5K
  • · Replies 2 ·
Replies
2
Views
1K