Urinary System Flashcards
Urinary System
Regulates Water Balance and Removes Harmful Substances
Osmoregulation
Maintenance of constant osmotic pressure in fluids of an organism by control of water and salt concentrations
Kidney
Produces urine that travels through ureters to bladder where it is stored and excreted through urethra
Contains millions of nephrons (filtering tubes)
Nephron
Tube with blood vessels closely associated to it
tube winds from cortex of kidney deeper into medulla, back up to cortex, then back to medulla
Drains in renal pelvis (center of kidney)
Bowman’s Capsule
Beginning of nephron tube
Afferent arteriole (part of renal artery) enters capsule and forms a dense ball of vessels (glomerulus)
Vessels exit out of capusel, becomes efferent arteriore
Convoluted Tubule
Proximal convulated tubule begins at bowman’s capsule, where filtrate is absorbed from blood moving through glomerulus
Ends with distal convuluted tubule which joins up with the collecting duct to send out waste
Loop of Henle
Found in middle of convoluted tube
Descending limb- down from proximal convoluted tubule
Ascending limb- upwards towards collecting duct
Efferent Arteriole
Efferent arteriole has branching capillaries that surround the convoluted tubule and eventually dump into renal vein as they exit the nephron
Collecting Duct
Distal convoluted tubule dumps into collecting duct, which descends toward center of kidney
Multiple nephrons share a single collecting duct
Dumps contents into renal pelvis, which then drains into ureter
Filtrations
Blood enters glomerulus, high amount of pressure forces water/solutes to exit capillary wall and enter bowman’s capsule
Salts and sugars can pass through
Large proteins and RBCs are too big
Filtrate goes to PCT
Secretion
Addition fluids/substances secreted into convoluted tubule as filtrate passes through
Fluids secreted from capillaries of efferent arteriole
These materials are selectively secreted via active and passive transport from capillary network
Reabsorption
Filtrate moves down loop of Henle, being more and more concentrated due to water flowing outward
Descending Loop= high concentration
Filtrate moves up loop of Henle, salts are actively and passively transported out (filtrate more dilute, interstitial fluid highly concentrated)
Filtrate enters and descends down collecting ducts towards renal pelvis
Passes by area where there is high concentration of salt in the outside interstitial fluid
Causes water to diffuse out of collecting duct (by the time it reaches renal pelvis, filtrate is highly concentrated urine)
Antidiuretic Hormone (ADH)
Vasopressin
Increases water reabsorption by body (anti-diarrhea)- increases aquaporins
Increases concentration of salts in urine
Increases permeability of collecting duct before it dumps into renal pelvis, allowing for more water absorption
Aldosterone
Increase reabsorption of Na, which naturally causes the reabsorption of water along with it
Increases permeability of DCT and collecting duct to Na
Increased concentration of Na causes water to come along via osmosis
Nitrogen Waste
Major waste product in animals due to breakdown of amino acids and nucleic acids
NH3 is toxic to animals, need to get rid of it
