Help plz on kidney function.

[whawha]

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I know this is quite basic stuff. But, I just don't seem to understand this statement even after reading so many times.

On the bottom of page 190 of Cliff Bio, it says, (in Secretion section)

"As the filtrate passes through the proximal tubule and, later, through the distal tubule, additional material from the interstitial fluids joins the filtrate. This added material, which originates from the capillary network surrounding the nephron, is selectively secreted into the convoluted tubule by both passive and active transport mechanisms"

Can someone explain the red-highlighted part? Shouldn't be "secreted into the interstitial fluid"?

 

[yumi43]

the additional material from the interstitial fluids will be secreted into the convoluted tubule as water is being reabsorbed by the body, creating more concentrated urine.

 

[Valigator00]

I know this is quite basic stuff. But, I just don't seem to understand this statement even after reading so many times.

On the bottom of page 190 of Cliff Bio, it says, (in Secretion section)

"As the filtrate passes through the proximal tubule and, later, through the distal tubule, additional material from the interstitial fluids joins the filtrate. This added material, which originates from the capillary network surrounding the nephron, is selectively secreted into the convoluted tubule by both passive and active transport mechanisms"

Can someone explain the red-highlighted part? Shouldn't be "secreted into the interstitial fluid"?

I think you are misreading the sentence. The capillary network releases the stuff (minerals, ions etc.) it does not want into interstitium. Once it gets to interstitium, it is selectively dumped into the nephron (either passively or through active transport). What ever material does not go to the nephron, goes through the lymph system.

 

[whawha]

Thank you all for replying... I still don't get this especially when looking at this picture in my book... Thank you again guys...

 

[whawha]

Thank you all for replying... I still don't get this especially when looking at this picture in my book... Thank you again guys...

My question from that diagram is, why are arrows pointing outward if it says "secreted into the convoluted tubule" ?

 

[whawha]

Is nephron not proximal and distal convoluted tubules....?

 

[Valigator00]

Is nephron not proximal and distal convoluted tubules....?

Nephron is the whole thing (proximal, loop of henle, distil, collecting duct). The arrows are pointing out, because certain materials such as h20 and Sodium Ions want to get into the blood system so things like blood pressure can be regulated. Think of kidney as an excretory organ. Body wants the good stuff while getting rid of the bad stuff. Secretion occurs in both ways. Hope this helps

 

[whawha]

Nephron is the whole thing (proximal, loop of henle, distil, collecting duct). The arrows are pointing out, because certain materials such as h20 and Sodium Ions want to get into the blood system so things like blood pressure can be regulated. Think of kidney as an excretory organ. Body wants the good stuff while getting rid of the bad stuff. Secretion occurs in both ways. Hope this helps

So, basically, those arrows are representing "reabsorption" step? Not secretion step? Then, where do secretions take place? (like from where to where?)

 

[whawha]

Oh, I think I know what I was thinking incorrectly. In Cliff, it has 1. Filtration 2. Secretion 3. Reabsorption

I thought those 1,2 and 3 represented the order, but I guess not. It should be filtration, reabsorption and secretion........ right?

 

[Valigator00]

So, basically, those arrows are representing "reabsorption" step? Not secretion step? Then, where do secretions take place? (like from where to where?)

Yes those are reabsorbtions. Secretion takes place throughout the nephron, but mostly in the distil convoluted tubule and collecting duct.

 

[whawha]

Can you tell me what is secreted out?

In Kaplan BB, I read,

"The nephron secretes susbstances such as acids, bases, and ions like potassium and phosphate from the interstitial fluid into the filtrate by both passive and active transport. Materials are secreted from the peritubular capillaries into the nephron tubule"

This sounds like, nephron secretes all those stuff into itself to me....

 

[Valigator00]

Can you tell me what is secreted out?

In Kaplan BB, I read,

"The nephron secretes susbstances such as acids, bases, and ions like potassium and phosphate from the interstitial fluid into the filtrate by both passive and active transport. Materials are secreted from the peritubular capillaries into the nephron tubule"

This sounds like, nephron secretes all those stuff into itself to me....

That doesn't make sense to me. I read it as well in Kaplan BB. Just understand that nephron is responsible for putting good things (glucose, certain salts, aa) into blood. I takes bad things from blood (urea). I think Kaplan bb could have worded that part a little bit better.

 

[whawha]

That doesn't make sense to me. I read it as well in Kaplan BB. Just understand that nephron is responsible for putting good things (glucose, certain salts, aa) into blood. I takes bad things from blood (urea). I think Kaplan bb could have worded that part a little bit better.

Yeah,,,that statement was straight from the book...you said that secretion particularly occurs in distal tubule and collecting duct,,, but it seems reabsorption occurs in collecting duct tho...

 

[Valigator00]

Yeah,,,that statement was straight from the book...you said that secretion particularly occurs in distal tubule and collecting duct,,, but it seems reabsorption occurs in collecting duct tho...

Blood reabsorbs most of the stuff in proximal tubule. Blood reabsorbs material along the rest of nephron, just not to the extent that it does in proximal tubule.

Nephron reabsorbs materials mainly in distil convoluted tubule and collecting duct.

secretion=to give away
reabsorbtion=to take

 

[whawha]

Blood reabsorbs most of the stuff in proximal tubule. Blood reabsorbs material along the rest of nephron, just not to the extent that it does in proximal tubule.

Nephron reabsorbs materials mainly in distil convoluted tubule and collecting duct.

secretion=to give away
reabsorbtion=to take

I am still a little confused,,, I got all the reaborption part in which kidney functions to conserve all the good things for our body. But, still confused by the term "secretion"...what exactly does nephron secrete..

I will just try to read it again and understand it. thank you so much tho 🙂

 

[whawha]

Where is the main area for secretion??

I am reading Cambell and Destroyer. Destroyer says, the distal convoluted tubule is the main area for secretion of K+ and H+ by active transport and NH3 by diffusion. But if you look at the picture that I provided, it doesn't seem true.

In proximal tubule, secretion of NH3 and H+ occurs where as secretion of H+ and K+ occurs in distal tubule....

 

[dentrilla]

hey sorry this is a lil off topic but i'm just wondering why Cliff's doesn't have that much info on human physio.. i'm assuming we have to know all the systems of the human body.

Guess every1's using kaplan BB / wiki for that?

 

[Valigator00]

hey sorry this is a lil off topic but i'm just wondering why Cliff's doesn't have that much info on human physio.. i'm assuming we have to know all the systems of the human body.

Guess every1's using kaplan BB / wiki for that?

Very true... don't rely on cliffs for physio in my opinion.

 

[dentrilla]

Very true... don't rely on cliffs for physio in my opinion.

yah im just hoping kaplan covers physio with the amount of detail that is required!