The kidney, ultrafiltration and ADH
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 4 practice questions, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Cleaning the blood
- The kidney
- The nephron
Read the transcript of the teaching part
Last time
Before we start: last time, in Stomata, auxin and gibberellin, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Cleaning the blood
Every day your kidneys filter about a hundred and eighty litres of fluid from your blood. Yet you pass only about a litre and a half of urine. So nearly everything filtered is taken straight back. The nephron is built to do exactly that, and ADH decides how much water comes back.
The kidney
The kidney has an outer cortex, an inner medulla, and a central pelvis that collects urine and leads to the ureter. The renal artery brings blood to the kidney, and the renal vein carries blood away. Each kidney contains about a million nephrons. The cortex contains the glomeruli and Bowman's capsules, with the convoluted tubules. The medulla contains the loops of Henle and collecting ducts.
The nephron
Blood enters the glomerulus, a knot of capillaries, by the afferent arteriole, and leaves by the narrower efferent arteriole. The Bowman's capsule surrounds the glomerulus. Filtrate then flows through the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule and the collecting duct. The proximal tubule cells have microvilli and many mitochondria, for reabsorption.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Osmoregulation and ADH · Ultrafiltration and selective reabsorption.
The whole chapter: Homeostasis.
Chapter 14: Homeostasis
- Homeostasis and the control of blood glucose 7 min
- The kidney, ultrafiltration and ADH 6 min
Also for A Level Biology 9700
Which topics come up most in A Level Biology 9700 past papers, counted from every paper since 2004: Paper 1 topic frequency, Paper 2 topic frequency, Paper 4 topic frequency.