kidney - urine produced from blood coming through renal artery
- ureter - carries urine to urinary bladder
- split into renal pelvis, renal cortex, renal medulla
- nephron - cells responsible for the filtration, reabsorption, secretion, excretion
- glomerulus - where blood gets filtered
- Bowman’s capsule - surrounds glomerulus like a balloon
- proximal convoluted tubule - extends into medulla, loops back to cortex; water gets reabsorbed
- loop of Henle - only found in mammals/birds >> ability to concentrate urine
- things not filtered go to efferent arteriole >> peritubular capillaries
- reabsorption/secretion - water, dissolved solutes must return to blood or else animal urinates to death
- solid molecules reabsorbed through active transport, cotransport
- substances get secreted by moving from blood capillaries to filtrate
- excretion - gets rid of harmful substances
transport in nephron - osmotic gradient needed for reabsorption
- proximal convoluted tubule - active transport of Na+ and Cl- >> reabsorption
- most of water reabsorbed through wall of collecting duct
- leaves behind hypertonic urine
- loop of Henle - creates the hypertonic renal medulla that draws water out from nephrons
- water permeates through descending limb
- water stays through ascending limb, NaCl leaves
- antidiuretic hormone (ADH) - aka vasopressin
- produced by hypothalamus, secreted by posterior pituitary gland
- more ADH >> less water in urine
- less ADH >> more water in urine
- aldosterone - maintains the Na+ levels (reabsorption), consequently water levels
- opposed by atrial natriuretic hormone (promotes excretion of salt/water)
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