Term: (Re)absorb / Secrete

[letaps]

Hey.

When they say reabsorb or absorb, do they mean that substances move from the lumen into the interstitial space?

and

When they say secret, do they mean that substances move from the interstitial space to the lumen?

Thanks

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[byeh2004]

Correct me if I'm wrong guys

Reabsorption = movement out int. space
Secretion = movement into int. space

 

[cornpops21]

Reabsorption basically means to retain in the body. If you have Na+ in your kidney filtrate, it gets reabsorbed....meaning that it goes from the filtrate back into the plasma, causing it to be retained by the body and not excreted in the urine.

Secretion means to get rid of something. The body seeks to remove excess H+ ions in the blood by secreting them INTO the urinary filtrate.

There's a pretty good picture. All the arrows pointing TOWARDS the nephron tubules means that substance is being SECRETED into the filtrate.

The arrows pointing AWAY from the tubules means that substance is being REABSORBED and therefore retained by the body.

 

[spyderracing32]

I take it this is in reference to the kidneys, and I used to have confusion about this too. Absorb is to remove water/solute from the lumen of the nephron (retaining water), and secrete is the move water/solute into the lumen to be excreted as urine. Really confusing terminology, and the only way I remembered it was to just beat it into my head (its not brain surgery or anything though).