L18: Tubular Reabsorption & Secretion

Question 1

paracellular routes run _____ cells, while transcellular goes ____ cells.

Answer 1

inbetween

thru

Question 2

A-1

Answer 2

aquaporins that are widespread throughout renal tubules

Question 3

A-2

Answer 3

aquaporins found on apical membranes of collecting tubule cells

controlled by ADH

Question 4

A-3

Answer 4

found on basolateral membranes of collecting tubule cells

Question 5

ENaC channel

Answer 5

apical membranes of nephron cells

closed by drug amiloride

opened by hormones

Question 6

CFTR channels and K+ channels

Answer 6

apical membranes of portions of the nephron

Question 7

Na-glucose ______ are found on brush border of ______ tubule cells

Answer 7

symporters

proximal tubule

Question 8

SGLT2 vs. SGLT1

Answer 8

2 absorbs 90% of glucose in early proximal tubule

1 absorbs 10% of glucose in late proximal tubule

Question 9

what is transport maximum

Answer 9

the limit to the rate at which the solute can be transported

Question 10

what is the limiting factor that determines transport maximum

Answer 10

due to saturation of a specific transport system

Question 11

what is threshold for glucose reabsorption

Answer 11

max = 375 mg/min

Question 12

what is the filtered load of glucose

Answer 12

filtered load = 125

the point at which glucose first begins to be excreted in urine

Question 13

rate of diffusion is determined by _______ _____ of the substance

Answer 13

electrochemical gradient

permeability of the membrane to the substance

Question 14

define solvent drag

Answer 14

osmotic mvt of water can also carry some solutes w/ it

Question 15

the proximal tubule is highly _____ and has extensive ?

Answer 15

metabolic - lots of mito

extensive brush borders
and intercell and basal channels

Question 16

proximal tubule reabsorbs

Answer 16

65% of filtered Na, Cl, K, bicarbonate

all filtered glucose and amino acids

Question 17

proximal tubule secretion

Answer 17

H+

organic acids and bases

Question 18

Na reabsorption occurs in the _____ half of the proximal tubule via ?

Answer 18

first half
Na-glucose symporter

second half
Na/Cl symporter

Question 19

how does bicarbonate enter a cell

Answer 19

it combines w/ H+ in lumen to = carbonic acid

carbonic anhydrase then splits the acid into CO2 and water

then can enter the cell

Question 20

what happens when CO2 and water enter a cell

Answer 20

they recombine into carbonic acid

dissociate into bicarbonate and H+

Question 21

what happens to intracell bicarbonate and H+

Answer 21

bicarbonate diffuses out basal domain

H+ is removed from cell via Na/H ATPase antiporters out apical domain into lumen

Question 22

describe permeability of the thin descending loop of henle

Answer 22

highly permeable to water

moderate permeability to urea and Na

reabsorbs 20% of filtered water

Question 23

the ascending loop of henle is impermeable to ?

Answer 23

water

Question 24

a slight back leak of K+ into lumen of the thick _______ loop of henle forces?

Answer 24

ascending loop

forces Mg and Ca to diffuse from lumen to interstitium via paracellular routes

Question 25

______ loop of henle is the site of action for powerful diuretics

Answer 25

thick ascending loop

Question 26

early distal tubule forms the

Answer 26

macula densa

Question 27

the late distal tubule is similar to the

Answer 27

thick ascending loop of henle reabsorbing most ions but impermeable to water and urea

Question 28

what type of epithelium lines the medullary collecting duct

Answer 28

cuboidal cells

Question 29

describe permeability of the medullary collecting duct

Answer 29

permeable to water controlled by ADH and urea via urea transporters

Question 30

the medullary collecting duct can secrete ___ against a high concentration gradient

Answer 30

H+

Question 31

medullary collecting duct reabsorbs ? secretes ?

Answer 31

absorb - Na, Cl, urea, bicarbonate water in presence of ADH secrete H+ into lumen

Question 32

location of principal cells

Answer 32

late distal/cortical collecting tubules

Question 33

principal cells reabsorb/secrete

Answer 33

reabsorb - Na and water secrete K into lumen using Na/K ATPase pumps

Question 34

intercalated cells

Answer 34

reabsorb K and bicarbonate secrete H+ into lumn

Question 35

in intercalated cells for each H+ secreted

Answer 35

a bicarbonate is reabsorbed across the basolateral domains

Question 36

net pressure forcing into blood stream

Answer 36

10 mmhg

Question 37

net pressure forcing into interstitium

Answer 37

28 mmhg

Question 38

source of aldosterone

Answer 38

adrenal cortex

Question 39

function of aldosterone

Answer 39

increase Na reabsorption stimulate K secretion via Na/K ATPase pumps on basolateral sides of cortical collecting tubules

Question 40

site of action for aldosterone

Answer 40

principal cells of cortical collecting ducts

Question 41

what stimulates the secretion of aldosterone

Answer 41

increased extracell k increased levels of angiotensin II

Question 42

Addison's disease

Answer 42

absence of aldosterone results in marked loss of Na and accumulation of K extracell

Question 43

conn's syndrome

Answer 43

hypersecretion of aldosterone

Question 44

function of angiotensin II

Answer 44

increase Na and water reabsorption return bp and extracell volume to normal

Question 45

effects of angiotensin II

Answer 45

stimulate release of aldosterone constrict efferent arterioles

Question 46

angiotensin II directly stimulates

Answer 46

Na reabsorption in proximal tubule, loop of henle, distal tubule, collecting ducts

Question 47

source and function of ADH

Answer 47

posterior pituitary increase water reabsorption

Question 48

source and function of ANP

Answer 48

cardiac atrial cells in response to distension inhibit reabsorption of Na and water

Question 49

source and function of ANP

Answer 49

parathyroid glands increase Ca reabsorption

Question 50

renal clearance =

Answer 50

volume of plasma that is completely cleared of the substance by the kidneys per unit time