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🧬 NEET Biology❓ Question

ADH, renin, aldosterone, ANF: I keep mixing which raises or lowers blood volume. Any clean way?

Aarav Kulkarni11th Sample

13 Oct 2026 · 1 min read

I am writing the regulation of kidney function section as a flowchart and I have now redrawn it four times because I keep mixing arrows.

What I have so far:

  • Osmoreceptors sense a change in body fluid volume/ion concentration, then ADH from the neurohypophysis helps water reabsorption in the latter part of the tubule, so less urine.
  • If GFR/blood flow falls, JG cells release renin, then angiotensinogen → angiotensin I → angiotensin II.
  • Angiotensin II is a vasoconstrictor, increases GFR and stimulates the adrenal cortex to release aldosterone.
  • Aldosterone: Na⁺ and water reabsorption in the distal tubule.
  • ANF from the atria... this is where it breaks. I know it lowers BP but I can't place it in the flowchart.

Questions: Is ANF a part of the same loop as the renin-angiotensin pathway or a different one? Does ADH also affect blood pressure or only water? And NCERT's last section has micturition, the other organs (lungs, liver, skin) and disorders (uremia, renal calculi, glomerulonephritis, dialysis) in a long paragraph; any short way to remember them?

I'm one of those people who needs a list for everything, so a table or numbered chain would help a lot 🙏

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8 answers & replies

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  • [+]Tanvi Deshmukh12thSample· 7d ago

    Table!!! You're going to love this 😍

    HormoneMade byTriggered byWhat it does
    ADHmade in hypothalamus, released from posterior pituitarybody fluid loss / high osmolarity (osmoreceptors)more water reabsorbed from the distal parts of the tubule, prevents diuresis; also constricts blood vessels, which can raise BP and GFR
    ReninJG cells of the kidneyfall in GFR / blood flow / BPconverts angiotensinogen → angiotensin I (then ACE → angiotensin II)
    Angiotensin IIformed in bloodreninvasoconstriction, raises GFR, stimulates aldosterone release
    Aldosteroneadrenal cortexangiotensin IINa⁺ and water reabsorbed in distal tubule, BP and GFR go up
    ANFatrial wall of the heartincreased blood flow to atria / high BPvasodilation, lowers BP, checks the renin-angiotensin mechanism
    • [+]Aarav Kulkarni11thSample· 6d agoAuthor

      Tanvi this table is going on my wall. Thank you!!

  • [+]Pooja Iyer12thSample· 7d ago

    My mnemonic: ADH = A Dramatic Hold (holds water), Aldosterone = Adrenal medulla's Little Dose of Sodium → okay so the medulla part is my bad rhyme but you get the idea 😅 Aldosterone makes the kidney hold sodium, and where Na⁺ goes water follows, so the volume goes up. ANF is the opposite team, "A Nice Fix" that relaxes the vessels when the atria get stretched.

    • [+]Zoya Khan12thSample· 7d ago

      Pooja, quick correction before Aarav puts it into the flowchart: aldosterone is from the adrenal cortex, not the medulla. The medulla makes adrenaline and noradrenaline. Tanvi's table has it right (and Angiotensin II is what tells the cortex to release it).

  • [+]Rahul DubeyDropperSample· 7d ago

    How I finally stopped redrawing: two directions only.

    Falling pressure / volume → kidney senses it → renin → Ang II → vasoconstriction + aldosterone → salt and water held → pressure goes up. ADH joins in from the brain side to hold water.

    Rising pressure / stretched atria → ANF → vessels dilate → pressure comes down, and it acts as a check on the renin pathway so the system doesn't overshoot.

    So to answer your question: ANF isn't a part of the renin loop, it's the opposing brake on it. Put it on the other side of the flowchart with the arrows pointing down. And yes ADH affects BP also (vasoconstriction), but its main job is water.

    • [+]Aarav Kulkarni11thSample· 6d agoAuthor

      Okay so ANF is the brake, not a part of the loop. Moved it to the other side of the page, and the whole page finally looks calm 😭 Thanks Rahul bhaiya

  • [+]Farhan ShaikhDropperSample· 6d ago

    Micturition + other organs, in the short form I use:

    • Bladder fills → stretch receptors send signals to CNS → CNS sends motor messages → bladder smooth muscle contracts + urethral sphincter relaxes → urine released. That's the micturition reflex (voluntary signal from CNS initiates it).
    • Normal adult: about 1-1.5 L urine/day, slightly acidic (pH ~6), about 25-30 g urea/day.
    • Lungs: CO₂ (~200 mL/min) and some water. Liver: bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins, drugs. Skin: sweat (NaCl, urea, lactic acid); sebaceous glands: sterols, hydrocarbons, waxes.
  • [+]Lakshmi TripathiDropperSample· 6d ago

    Disorders in one line each:

    • Uremia: too much urea in the blood, can lead to kidney failure.
    • Haemodialysis: blood is drawn from an artery, heparin is added, it passes through a cellophane tube bathed in dialysing fluid (same as plasma but without nitrogenous waste), then returned to a vein after anti-heparin.
    • Kidney transplant: best long-term option, donor usually a close relative to reduce rejection.
    • Renal calculi: stones of crystallised salts like oxalates in the kidney.
    • Glomerulonephritis: inflammation of the glomeruli.

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