HOMEOSTASIS IN THE URINARY SYSTEM Functionmaintenance of homeostasis

HOMEOSTASIS IN THE URINARY SYSTEM

Function-maintenance of homeostasis � � � a. Regulation of water content in the blood In the case of dehydration, sensors in the brain stimulate the release of the hormone ADH (antidiuretic hormone also called vasopressin) ADH is released from the pituitary It passes through the blood to the kidneys where it stimulates the release of water back into the blood from the distal tubule and the collecting duct. When water balance is normal, the ADH secretion is stopped. Chapter 30 2

Chapter 30 3

� � b. Regulation of levels of molecules in the blood Penicillin, salicylates (aspirin) excreted glucose, proteins, and amino acids are all reabsorbed. phosphate, sulfate, lactate, vit. C all reabsorbed. Chapter 30 4

� � c. Maintenance of blood p. H Most important buffer system is bicarbonate ion (HCO 3 - ) buffers maintain constant p. H kidney reabsorbs bicarbonate when blood is acidic and produces bicarbonate to further buffer the blood. Chapter 30 5

� � d. Regulation of blood pressure and oxygen content when blood pressure falls, kidneys release renin into the blood. This causes formation of angiotensin causes arterioles to constrict increasing blood pressure. Constriction also causes less blood to be filtered, maintaining water balance and further increasing blood pressure. for low oxygen levels, kidneys release erythropoietin, stimulating red blood cell growth Chapter 30 6

Renal Pelvis Renal Cortex Renal Artery Nephron Renal Medulla Cross Section of a Kidney Renal Vein Renal Pelvis Ureter Chapter 30 7

Regulation of Water in Blood � � � Sensors in hypothalamus gauge osmotic concentration Deviations cause posterior pituitary to turn ADH release on or off ADH restores blood osmotic concentration �Red = increased osmotic concentration �Green = decreased osmotic concentration Chapter 30 1 5 2 3 4 8

Chapter 30 The End