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CBSE Class 11 · Biology

Excretory Products and their Elimination

Official NCERT chapter from Biology (book code kebo1). ExamMaster notes are original teaching at CBSE Class 11 depth.

This lesson follows the official chapter “Excretory Products and their Elimination” in Biology. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.

  • CBSE Class 11
  • Medium level
  • 8 concepts

1Human Excretory System

Human excretory system: kidneys, ureters, bladder, urethra as the path as taught. A kidney is the filter-organ; the rest are the drain-path. System is name-plus-job, not a water-ad.

A lung as the excretory organ because it loses some CO2 is a side-look — not this path unless the lesson listed it later.

Figure. A pair of kidneys sit above the bladder. Each ureter is a one-way pipe; the urethra is the exit. Topology only — not a body outline.

How it works

  1. Name kidney and the drain-pathThe system.
  2. Attach filter as the kidney-jobWhy it sits.
  3. Keep a lung-CO2 mention for the other-organs heading if taughtThis path first.

2Urine Formation

Urine formation: filtration, reabsorb, secrete as the three school steps if named. Formation is those steps, not “kidney makes water”. A nephron as the unit if taught. One honest trio is enough.

A bladder-squeeze as “formation” is a miss — that is micturition.

Figure. Urine is made in three jobs: filter at the glomerulus, reabsorb useful solute and water, then secrete extras. Atoms are not deleted.

How it works

  1. Name filter → take-back → add as taughtFormation.
  2. Keep the nephron as the unit if askedWhere.
  3. Refuse a store-and-release as this headingLater.

3Function of the Tubules

Function of the tubules: take back useful bits (water, glucose as taught) and add extras. Tubules are the adjust-path after the filter. A mute “tubule” sticker without a take-back is not this heading.

Dumping all filtrate as urine is the leftover the tubules refuse.

Figure. Each tubule stretch has one job. PCT takes back food and water; the loop builds the salt grade; DCT tunes salt; the collecting duct moves water only if ADH is present.

How it works

  1. Name take-back of useful bitsTubule job.
  2. Add secrete if taughtThe extra.
  3. Keep glucose-in-urine as a fail-hint only if namedHonest.

4Mechanism of Concentration of the Filtrate

Concentration of the filtrate (school): a counter-current / loop look as taught that saves water. Concentration is a water-save, not a “stronger colour” quiz. One loop-mention is enough; no research dump.

A dark-colour as the whole mechanism is a glance.

Figure. The medulla is saltier deeper in: 300 at the cortex, 1200 at the bend. Descending filtrate loses water; ascending filtrate loses salt. A U-shape would need an arc, so the two limbs are drawn as columns.

How it works

  1. Name the taught loop / counter-current lookThe mechanism.
  2. Say water is savedThe job.
  3. Refuse a colour-quiz as the scienceA save-word.

5Regulation of Kidney Function

Regulation of kidney function: ADH / a pressure-cue as taught — a signal that adjusts water-save or filter-rate. Regulation is a cue, not a mood. Keep it a name-plus-what-it-adjusts.

A “drink less” slogan as ADH is a skip of the signal.

Figure. Two school regulators: low water releases ADH so the collecting duct keeps water; low GFR fires the JGA so salt is kept. ANF is the opposite volume brake and is not drawn here.

How it works

  1. Name the taught cue (ADH or pressure)Regulation.
  2. Attach water-save or rate-adjustThe job.
  3. Refuse a lifestyle-manualSchool-size.

6Micturition

Micturition: store then release as taught — a reflex-plus-control as framed. Micturition is the exit-step, not formation. Stage-names only; no extra how-to.

Calling filter “micturition” is a step-swap.

Figure. Micturition is a reflex path: a full bladder stretches, the CNS is told, then the sphincter opens. Filling alone is not voiding.

How it works

  1. Name store then releaseMicturition.
  2. Keep it the exit-stepNot formation.
  3. Stay on stage-namesThis class.

7Role of Other Organs in Excretion

Other organs in excretion: lungs (CO2), skin (sweat salts), liver (as taught) — extras beside the kidney-path. Other-organs is a side-list, not a second kidney.

Skipping the kidney because “skin sweats” is a steal.

Figure. Lungs drop carbon dioxide, liver makes urea, skin loses salt in sweat. The kidney is the main nitrogen exit, not the only excretory organ.

How it works

  1. Name lung / skin / liver as taughtThe extras.
  2. Keep the kidney as the main filterThe path.
  3. Refuse extras as the whole systemA side-list.

8Disorders of the Excretory System

Disorders: a named kidney-fail (stone, uremia as taught) as name-plus-what-fails. Not a scare, not a treatment-manual. Dialysis as a named stand-in if the lesson used it — a job-sentence, not a clinic-guide.

A skull-sticker with no fail-word is a mute scare.

Figure. Haemodialysis is a path, not a kidney drawing: blood in, waste into the bath, cleaned blood back. Uremia is what this path is for.

How it works

  1. Name the taught disorder or stand-inThe word.
  2. Say which job failedThe claim.
  3. Refuse a how-to clinic-listSchool-size.
Urine formation’s school trio is
  1. Filter, reabsorb, secrete as taught
  2. Only micturition
  3. Only a sweat

Three steps, not the exit.

Notes

  • Mapped to the official NCERT chapter “Excretory Products and their Elimination”. Original teaching only — no textbook sentences.
  • Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.

Recap

Hold these pegs from the official chapter “Excretory Products and their Elimination”. The wording is ExamMaster’s teaching, not a textbook recap.

Human Excretory System
Human excretory system: kidneys, ureters, bladder, urethra as the path as taught.
Urine Formation
Urine formation: filtration, reabsorb, secrete as the three school steps if named.
Function of the Tubules
Function of the tubules: take back useful bits (water, glucose as taught) and add extras.
Mechanism of Concentration of the Filtrate
Concentration of the filtrate (school): a counter-current / loop look as taught that saves water.
Regulation of Kidney Function
Regulation of kidney function: ADH / a pressure-cue as taught — a signal that adjusts water-save or filter-rate.
Micturition
Micturition: store then release as taught — a reflex-plus-control as framed.

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