This topic summary covers Knowledge Organiser within Water Regulation for GCSE Biology. Topic 7: Water Regulation It is section 10 of 11 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 10 of 11
Practice
15 questions
Recall
20 flashcards
Knowledge Organiser
Key Terms
- ADH: Antidiuretic hormone; increases water reabsorption in kidney
- Osmoregulation: Control of water and salt balance in blood
- Nephron: Functional unit of the kidney
- Filtration: Forced removal of small molecules from blood into nephron
- Selective reabsorption: Return of useful substances (glucose, water) to blood
- Urea: Waste from amino acid breakdown; excreted in urine
- Collecting duct: Region where ADH controls water reabsorption
- Aquaporin: Protein channel in collecting duct wall; ADH inserts more aquaporins to increase water permeability
Must-Know Facts
- ADH is produced by hypothalamus; released by pituitary gland
- Dehydration → more ADH → more water reabsorbed → concentrated urine
- Over-hydration → less ADH → less water reabsorbed → dilute urine
- Nephron stages: Filtration → Selective Reabsorption → Excretion
- Glucose is always fully reabsorbed (glucose in urine = diabetes)
- Urea is formed in the liver; excreted by kidneys
- Dialysis (ongoing) vs transplant (long-term but limited donors)