44.4 blood filtrate to urine

Question 1

steps the filtrate goes through in the nephron and the collecting duct

Answer 1

1- proximal tube 2-descending limb of the loop of Henle 3- ascending limb of the Henle 4- Distal Tube 5- Collecting Duct

Question 2

Proximal Tube: what happens

Answer 2

-reabsorption - cortex -NaCl diffuses into the cells of the transport epithelium -Na+ is actively transported into interstitial fluid -this transfer of + charge drives the passive transport of Cl- -salt and water diffuse from interstitial fluid to peritubular capillaries -glucose, amino acids, and K+ are also active/passive transported from filtrate->interstitial fluid->peritubular capillaries

Question 3

proximal tube: pH

Answer 3

-maintains pH (ammonia and bicarbonate) -cells of transport epithelium secrete H+ and synthesize ammonia -ammonia acts as a buffer to trap H+ in the form of ammonium ions (NH4+) -the more acidic the filtrate, the more (NH4+) is secreted -reabsorbs buffer: bicarbonate (HCO3-) is also reabsorbed

Question 4

descending the loop of the Henle:

Answer 4

-reabsorption of water -the epithelial cells have so many aquaporins proteins, water diffuses freely -the epithelial cells barely have any channel proteins for salt and small solutes -filtrate loses water and gains solute- every step down they go (because osmolarity increases from cortex to medulla)

Question 5

osmolarity increase form ______to______

Answer 5

cortex to medulla

Question 6

ascending the loop of Henle

Answer 6

-opposite of descending -epithelial cells have solute channels but no water channels -thin segment: NaCl diffuses out into the interstitial fluid -thick segment: NaCl Actively transports out into the interstitial fluid -makes filtrate more dilute cuz it loses solute

Question 7

distal tube

Answer 7

-regulates K+ and NaCl concentration -secretes some K+ into filtrate -reabsorbs some NaCl from filtrate -controls pH -secretes H+ -reabsorbs HCO3-

Question 8

collecting duct

Answer 8

-carries filtrate through the medulla to the renal pelvis -along the way, it loses water -in the inner medulla the collecting duct gets permeable to urea - -some urea diffuses out into the interstitial fluid -results in urine that is hyper osmotic to body fluids -NaCl can be actively transported out of filtrate