Blood is filtered under pressure in the Bowman's capsule. The filtrate is the same composition as blood plasma except for an absence of large proteins and a lower protein concentration. Substances in the filtrate include amino-acids, urea, glucose, water and inorganic ions such as sodium, chloride and potassium ions. Glucose, amino-acids and inorganic ions are selectively reabsorbed in the proximal convoluted tubule.Over 80% of the water is reabsorbed in the proximal convoluted tubule and a large portion of the remaining water is absorbed in the loop of Henlé. The amount of water reabsorbed depends on the needs of the body and the rest of the water is reabsorbed under the control of the hormones ADH and aldosterone. Less than 10% of the filtrate reaches the collecting ducts.
Ultrafiltration, Selective Reabsorption and Osmoregulation.
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Specification: AQA Biology (7402), A-level, 3.6.4.3 Control of blood water potential. Topic: Homeostasis.
More in Homeostasis
- Glomerulus
- Proximal Convoluted Tubule
- Loop of Henlé
- Countercurrent Multiplier
- Distal Tubule and Collecting Duct
- ADH
- Kidney failure
- Haemodialysis
All 33 lessons in Homeostasis · All AQA A-level Biology topics