Lesson Review. The Role of the Kidney It plays a central role in homeostasis, Function : The primary role of the Kidneys is osmoregulation Role 2 : Excretion of all nitrogenous wastes. Fresh Water fish. Fish (bony) living in freshwater are hypertonic to their surroundings.
This liquid consists of urea, glucose, amino acids, some hormones, vitamins, salts and water (no plasma proteins or blood cells).
In the distal tubule – selective reabsorption and secretion again occur to adjust pH of the blood and level of salts particularly sodium and potassium.
Diffusion and osmosis are passive forms of transport that do not require the expenditure of energy.
In the kidneys both forms of transport are use in the regulation of the body fluid composition.
Diffusion and osmosis are both examples of passive transport, relying on the random movement of molecules. Diffusion is too slow for the normal functioning of the body and does not select for useful solutes.
Antidiuretic hormone (ADH or vasopressin) controls water reabsorption in the nephron. Made in the hypothalamus.