The kidney and osmoregulation 11.3 (HL)

This is just for HL students. There is now in the new syllabus a small change of emphasis towards osmoregulation.

The syllabus:

new syllabus 11.3 anew syllabus 11.3 b

Introductory Reading (from Biology in Context): Excretion, osmoregulation, kidney structure and nephron structure


Excretion and nitrogenous waste in the animal kingdom

  1. Reading: nitrogenous excretion other animals

  2. A research and worksheet: EXCRETION OF NITROGENOUS WASTES table

The kidney and nephronkidney_large_1nephron

More reading

Ultrafiltration and selective reabsorptionkidney reabsorption 1kidney reabsorption 2

Loop of Henlé, reabsorption of water and osmoregulation240241242243reabsorption kidney

Visualising osmoregulationosmoregulation imageosmoregulation in kidneys 2

Learning powerpoints

  1. Simple introduction of just 5 slides: kidney ppt 5 slides
  2. Complete: Kidneys ppt
  3. Complete: THE KIDNEY paul billiet
  4. Focus upon the hard bits – ultrafiltration and selective reabsorption: ultrafiltration-and-selective-reabsorption

Nature of Science

Curiosity about particular phenomena – investigations were carried out to determine how desert animals prevent water loss in their wastes.

This is a link to Simon Underhill’s NoS Blog, where the osmoregulatory control of desert rats, is described so nicely. Understanding this should help greatly in an understanding of how the kidneys and especially the loops of Henlé function, as well as contribute to properly grasping the NoS context.

Get into it deeper – the desert rat


The desert rat has extreme adaptations for conservation of water. This forms the basis for the NoS context (see above and see the NoS page in the companion abcbiology blog: but a run through this slideplayer show (from where the image above was taken) will help in a good comprehension of the way in which osmoregulation is managed in different organisms. (The content is some way beyond what is necessary for IB preparation but if you enjoy this sort of animal physiology, give it a go. I certainly enjoy this sort of thing!)

Comparing the composition of fluids in the kidney (Blood, filtrate and urine)

table urine blood


  1. Labelling the kidney and nephron:kidney-nephron numbered

  2. IB past paper questions

Eyyy! left to right