Physio 4

Question 1

secretion

Answer 1

the movement of solutes from the circulation via the peritubular capillaries across the epithelial cell tubule into the tubular fluid

Question 2

what is urine formed by?

Answer 2

formed by the solutes and the water NOT reabsorbed as well as solutes secreted into the tubular fluid

Question 3

two methods of renal epithelial transport

Answer 3

transcellular and paracellular

Question 4

transcellular transport

Answer 4

depends on solute specific transporters in the apical membrane facing the tubular fluid in the lumen and in the basolateral membrane facing the peritubular space and capillaries. Na/K ATPase are on the basolateral membrane.

Question 5

secondary active transport

Answer 5

transduce energy stored in the electrochem gradient of one solute into the energy in the formation of a gradient of a second solute

Question 6

paracellular transport

Answer 6

passive and driven by a transepithelial solute electrochem gradient. depends on the tightness, or solute-specific resistance to transport of the intercellular junctions. movement of water may entrain the solute movement through solvent drag, which contributes to transtubular solute reabsorption or secretion

Question 7

tubular reabsorption of a solute may result from:

Answer 7

1. active transport at the luminal membrane and passive transport at the baolateral membrane
2. passive transport at luminal and active transport at basolateral

Question 8

tubular secretion of a solute may result from

Answer 8

1. active transport at basolateral and passive transport at luminal
2. passive at basolateral, and active at lumenal

Question 9

what does the handling of glucose by nephron include?

Answer 9

filtration and reabsorption, but NOT secretion. amount of glucose in the urine is a function only of the amount filtered and the amount reabsorbed. first tubular segment of the nephron (proximal tubule) does this

Question 10

filtered load

Answer 10

amount of solute filtered at the glomerulus and is quantified as the product of solute concentration in the glomerular filtrate times the GFR.

Question 11

Tm

Answer 11

tubular reabsorptive maximum defining the maximum solute reabsorptive rate or capacity for tubular solute reabsorption

Question 12

what is the clearance of glucose when you have normal blood glucose?

Answer 12

0. this is because it’s all being reabsorbed. UV/P. U is 0, so the clearance is 0

Question 13

glucose transporter on lumenal membrane

Answer 13

Na+ / glucose cotransporters mediate concentrative accumulation of glucose into the cell. stoichiometry is 1 or 2 to 1, resulting in net positive charge transfer

Question 14

glucose transporter on basolateral membrane

Answer 14

passive efflux of intracellular glucose mediated by facilitated diffusion (uniporter)

Question 15

phosphate reabsorption

Answer 15

proximal tubular phosphate reabsorption increases with increasing filtered load of phosphate and approaches a tubular maximum where the process of transcellular phosphate transport becomes saturated and the rate of phosphate reabsorption becomes maximal and constant

Question 16

phosphate reabsorption on the lumenal membrane

Answer 16

Na+ / PO4 cotransporter. 2 or 3 to 1 stoichiometry, resulting in net positive charge transfer with each PO4 transported

Question 17

phosphate reabsorption on the basolateral membrane

Answer 17

passive efflux of intracellular PO4 mediated by facilitated diffusion

Question 18

things that get secreted

Answer 18

foreign drugs and toxins, things metabolized by the kidney for excretion by the kidney, things metabolized by the liver, and things regulated in the blood (H+ and K+ concentration)

Question 19

renal handling of p-aminohippuric acid

Answer 19

exogenous, nonmetabolizable prototype organic anion used to study renal organic anion secretion. secreted into tubular fluid but not reabsorbed. amount of PAH excreted in the urine is a function of the amount filtered as well as the amount secreted by the tubule

Question 20

transport of PAH on the basolateral membrane

Answer 20

Na / Dicarboxylate cotransporter mediates concentrative accumulation of dicarboxylate inside the cell.

an organic anion antiporter mediates exchange of ketoglutarate for extracellular PAH. 1 to 1 ratio in stoichiometry.

Question 21

transport of PAH on the lumenal membrane

Answer 21

efflux of intracellular PAH occurs by facilitated diffusion or anion gradient driven antiport

Question 22

what does clearance of PAH measure

Answer 22

renal plasma flow.

Question 23

renal handling of salicylate

Answer 23

active and passive transport help with secretion. reabsorption occurs by passive proces of nonionic diffusion across distal nephron. decreases with increased tubular fluid pH and flow, and vice versa

Question 24

reabsorption

Answer 24

movement of filtered solutes and water from the tubular fluid across the epithelial cell tubule into peritubular capillaries and the circulation