Renal Tubular Transport

Question 1

polydipsia

Answer 1

drinking excessively

Question 2

polyuria

Answer 2

urine output > 2000mL

Question 3

water reabsorbed?

Answer 3

99%

Question 4

sodium reabsorbed?

Answer 4

99.5%

Question 5

glucose reabsorbed?

Answer 5

100%

Question 6

urea reabsorbed?

Answer 6

50%

Question 7

transcellular

Answer 7

through the cell

Question 8

paracellular

Answer 8

between cells (through tight junctions)

Question 9

simple diffusion

Answer 9

down gradient

Question 10

facilitated diffusion

Answer 10

down gradient, requires carrier

Question 11

primary active transport

Answer 11

against gradient

ATP hydrolysis

Question 12

secondary active transport

Answer 12

against gradient
coupled to another substance moving down its gradient

cotransport or countertransport

Question 13

pinocytosis

Answer 13

protein reabsorption

Question 14

reabsorption at proximal tubule

Answer 14

Na, K, Cl, bicarbonate, Ca, phosphate

normally reabsorbs all glucose and amino acids

Question 15

secretion at proximal tubule

Answer 15

several organic anions and cations

drugs, drug metabolites, creatinine, urate

Question 16

water sodium potassium?

Answer 16

all reabsorbed equal quantities

no change in concentration along proximal tubule

Question 17

above flat line in concentration graph for PT?

Answer 17

absorbed at lower rate than water

Question 18

below flat line in concentration graph for PT?

Answer 18

absorbed at higher rate than water

Question 19

above inulin line?

Answer 19

is secreted

Question 20

fraction of filtered water reabsorbed?

Answer 20

look at inulin concentration ratio

3:1

Question 21

TF/P ratio

Answer 21

describes reabsorption as it moves down proximal tubule

glucose TF/P = 0

Question 22

PAH TF/P

Answer 22

secreted

TF/P = 10

Question 23

sodium reabsorption

Answer 23

linked to transcellular transport of other substances

Question 24

Na/H countertransporter

Answer 24

in proximal tubule

uses sodium gradient

Question 25

Na/Glucose cotransporter

Answer 25

in proximal tubule uses sodium gradient

Question 26

Na/K/2Cl cotransporter

Answer 26

in loop of henle uses sodium gradient

Question 27

water reabsorption in PCT?

Answer 27

follows Na+ reabsorption bulk flow

Question 28

Cl- and urea in PCT?

Answer 28

paracellular reabsorption -dependent on Na and H2O reabsorption concentration gradient between lumen and peritubular interstitum provides driving force not reabsorbed as rapidly

Question 29

factors promoting fluid movement into peritubular capillaries?

Answer 29

high plasma colloid osmotic pressure low hydrostatic pressure in capillaries almost as much fluid is reabsorbed as was initially filtered into bowmans capsule

Question 30

organic nutrient handling?

Answer 30

large amounts of nutrient filtered each day small molecules completely reabsorbed in proximal tubule (no reabsorption in distal)** glucose and amino acids

Question 31

regulation of plasma concentration of glucose and AAs?

Answer 31

liver and endocrine system NOT kidneys

Question 32

reabsorption of glucose and amino acids?

Answer 32

secondary active transport -only transcellular exit cell through facilitated diffusion

Question 33

Na/K ATPase

Answer 33

estabilishes sodium gradient to drive other substance transport

Question 34

Na/glucose cotransport

Answer 34

moves glucose from lumen to inside cell

Question 35

facilitated diffusion of glucose?

Answer 35

across basolateral membrane from cell to interstitium

Question 36

glucose saturable?

Answer 36

limited number of Na/glucose cotransporters in luminal membrane will result in glucosuria -same principles in amino acid transport

Question 37

Tmg

Answer 37

tubular glucose maximum | -max rate of glucose reabsorption by all nephrons combined

Question 38

filtered load

Answer 38

plasma concentration x GFR

Question 39

initiation of thirst?

Answer 39

by increased osmolarity

Question 40

osmotic diuretisis

Answer 40

raised filtrate osmolarity causes water to remain in tubule (not reabsorbed) also have increased sodium excretion

Question 41

tertiary active transport

Answer 41

secretion of organic anions -PAH, bile salts, uric acid, creatinine drugs like penicillin, salicylates, antiviral drugs transcellular transport

Question 42

PAH secretion?

Answer 42

it is saturable

Question 43

secretion of organic cations?

Answer 43

catecholamines, acetycholine, dopamine | in proximal convoluted tubule

Question 44

passive diffusion?

Answer 44

organic acids and bases charged forms, cannot readily diffuse protonation or deprotonation can make it neutral

Question 45

weak acids

Answer 45

neutral when protonated

Question 46

weak bases

Answer 46

neutral when deprotonated

Question 47

H+ in tubular lumen

Answer 47

favors reabsorption of organic acids and traps organic bases in lumen

Question 48

overdose of aspirin

Answer 48

want to excrete the salicylic acid | -treat with bicarbonate to help them excrete it

Question 49

what pulls materials to peritubular capillaries

Answer 49

bulk flow