I need help with bio:Kidney

[joonkimdds]

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Hello~!

I have questions about kidney.

K+ is secreted, Na+ and water are reabsorbed.
What others can be secreted or reabsorbed? and where does that happen?


I learned that descending loop of henle is where water can be absorbed. What happen in ascending loop? and is decending loop the only place that water can be absorbed or can it happen in other places such as proximal/distal convoluted tubule and collecting tubule?

Basically i know different components of nephron and but I don't know what happens at where. For example, I don't know what happens in proximal convoluted tubule. All I learned is that secretion and reabsorption happen there, but what is being secreted and reabsorbed is not taught in my class.


My books only talk about general idea like what I wrote above, K+,Na+, water and hormones but it doesn't talk about other details and so I need some help 😉

 

[razblo]

Also water can be reabsorbed in the collecting duct, depending on if ADH (antidiuretic hormone) is released or not.

 

[joonkimdds]

Also water can be reabsorbed in the collecting duct, depending on if ADH (antidiuretic hormone) is released or not.

Thanks for the pic.

I got some questions about this pic.

1) Is water permeability of decending loop not depending on ADH?
if so, ADH only affect in the area of collecting duct?
And I learned that water absorption with ADH happens when Na+ is absorbed, so I guess Na+ absorption also takes place in the collecting duct?


2)I thought K+ are always secreted in opposite direction of Na+. I see K+ and Na+ being absorbed to the same direction. If that's what's really happening in ascending loop, where does K+ secretion happen?

3) what do we need to know about the area of convoluted tubule?
I know that proximal convoluted tubule is ciliated so I am assuming that most of absorption takes place there.


I will try to read and search more to find answers to my own questions, too.

 

[achilles2]

Thanks for the pic.

I got some questions about this pic.

1) Is water permeability of decending loop not depending on ADH?
if so, ADH only affect in the area of collecting duct?
And I learned that water absorption with ADH happens when Na+ is absorbed, so I guess Na+ absorption also takes place in the collecting duct?


2)I thought K+ are always secreted in opposite direction of Na+. I see K+ and Na+ being absorbed to the same direction. If that's what's really happening in ascending loop, where does K+ secretion happen?

3) what do we need to know about the area of convoluted tubule?
I know that proximal convoluted tubule is ciliated so I am assuming that most of absorption takes place there.


I will try to read and search more to find answers to my own questions, too.

that pic is a GROSS over simplification, the kidney has many parts each with there own unique ion transport properties.

The net effect is absorption of Na+ and excretion of K+, however, various parts may actually pump Na+ into the lumen or blood and vice versa.

Most K+ excretion occurs in the collecting duct (this is where K+ sparing diuretics work) also where aldosterone makes its presence felt, it increases water channels so h20 can escape back into the blood (increases blood pressure)

Most re-absorption occurs in the proximal tubules however, the distal tubules also can absorb (distal tubuals is where carbonic acid diuretics work).

Renin I think has no direct effect on the kidney instead it causes the angiotension cascade to initate which ultimately releases aldostrone from the adrenal cortex and that then acts on the kidney.....spironolactones can competitvely inhibit aldosterone and is another possible diuretic.


Renal system is VERY complicated heres the cliffs notes:
1) most reabsorption (glucose and such) occurs in the proximal tubules
2) heavy proteins like albumin should NOT be filted into the lumen of the kideny you got major problems if they do lol
3) amino acids can diffuse into the lumen and are reabsorpted in the proximal tubules
4) as you approach the medulla of the kidney the ion concentration increases
5) spirolactones compete with aldosterone in the collecting duct
6) kidney re-absorbs Na+ and excretes K+
7) Na+/K+ ATPase sets up the ion gradiants that drive pretty much all the transport in the kidney
8) water transport is passive it follows the ionic concentration
9) in stress situations and low blood pressure the kidney secretes renin which ultimately releases aldosterone from the adrenal cortex which acts as an anti-duretic
10) in conditions of excessive blood glucose, the kidney can not re-absorp all the glucose at the tubules and you will lose glucose in urine, water will follow as its transport is passive thus excessive glucose can act as a diuretic (see that diabetes insipidious condition)

 

[joonkimdds]

achilles2//
thanks for great info.
But I am not sure about ADH explanation of cliff notes.
In my human physiology and general bio2, I learned that aldosterone helps reabsorption of Na+ and ADH increases water permeability to reabsorb water.

But I guess what's really important here is
1) most reabsorption takes place in PCT.
2) water is reabsorbed to increase concentration of urine at descending loop of henle.
3) K+ secretion, Na+ and water reabsorption happens at collecting duct with help of hormones.


I will look for the info about ADH that you wrote about and come back~

 

[razblo]

I know it's not the greatest representation of the neprhon but he was asking about the Loop of Henle, so I thought I'd post a power point slide from my physiology class that might help him visualize it.

 

[achilles2]

achilles2//
thanks for great info.
But I am not sure about ADH explanation of cliff notes.
In my human physiology and general bio2, I learned that aldosterone helps reabsorption of Na+ and ADH increases water permeability to reabsorb water.

But I guess what's really important here is
1) most reabsorption takes place in PCT.
2) water is reabsorbed to increase concentration of urine at descending loop of henle.
3) K+ secretion, Na+ and water reabsorption happens at collecting duct with help of hormones.


I will look for the info about ADH that you wrote about and come back~

WOW I am an IDIOT!!!! I confused ADH (vasopressin) with renin😱

good catch before i screwed over everyone lol

ADH first off is made in the hypothamlus and stored in the posterior pituatary and yeah it does have direct effects by V2 receptors on the kidney


Whoa my bad good save👍