Homeostasis & ResponseIntroduction

The Story: Your Body's Water Filter

Part of Water RegulationGCSE Biology

This introduction covers The Story: Your Body's Water Filter within Water Regulation for GCSE Biology. Topic 7: Water Regulation It is section 1 of 11 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 1 of 11

Practice

15 questions

Recall

20 flashcards

💧 The Story: Your Body's Water Filter

Your kidneys filter roughly 180 litres of blood every single day — enough to fill a bathtub. Yet you only produce about 1–2 litres of urine. What happens to the other 178 litres? The answer is selective reabsorption: your kidneys take back exactly what your body needs and discard the rest. The precision of this process is staggering. Whether you drink a litre of water or run a 10 km race without a sip, a hormone called ADH adjusts the kidneys minute-by-minute to keep your blood water concentration almost perfectly constant. This is osmoregulation — one of the most finely tuned control systems in the human body.

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Read this section alongside the surrounding pages in Water Regulation. That gives you the full topic sequence instead of a single isolated revision point.

Practice Questions for Water Regulation

Where does the filtration of blood take place in the kidney?

  • A. Kidney tubule
  • B. Collecting duct
  • C. Glomerulus
  • D. Ureter
1 markfoundation

Describe the process of selective reabsorption in the kidney and explain why it is important.

3 marksstandard

Quick Recall Flashcards

What is osmoregulation?
Osmoregulation is the control of the water content and ion concentration of the blood. The kidneys are the main organs responsible for this.
What is ADH and what does it do?
ADH (antidiuretic hormone) is released by the pituitary gland. It makes the kidneys reabsorb more water from the filtrate back into the blood, producing smaller amounts of more concentrated urine.

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