BRAINCAKEUltrafiltration, Selective Reabsorption and Osmoregulation.
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.
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Key terms in this lesson
- Hormone
- A chemical messenger, secreted directly into the blood by an endocrine gland, that travels to target cells and alters their activity.
- Osmoregulation
- The control of the water potential of the blood and body fluids.
- Ultrafiltration
- The filtration of blood under high hydrostatic pressure through the basement membrane of the Bowman's capsule, producing a filtrate free of large proteins and cells.
- Selective reabsorption
- The process by which useful substances such as glucose, amino acids, ions and water are reabsorbed from the filtrate back into the blood, mainly in the proximal convoluted tubule.
- Loop of Henle
- The part of the nephron that dips into the medulla and, through a countercurrent multiplier mechanism, creates a low water potential that allows water to be reabsorbed from the filtrate.
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 OCR A-level Biology topics