Sweep 1.3

Question 1

Reabsorption in the proximal tubule

1. Glucose and amino acids are rebsorbed with

Answer 1

Na+ using symporters

Question 2

Reabsorption in the proximal tubule

2. Active transport on ——–, keeps intracellular —– low

Answer 2

basal side

Na+

Question 3

Reabsorption in the proximal tubule

3. Water (and solutes) move via ——–; keeps the osmolarity of the tubular fluid —-

Answer 3

paracellular transport

constant

Question 4

Reabsorption in the proximal tubule

4. Na+ reabsorption also occurs in conjunction with bicarbonate reabsorption using a ———-

Answer 4

Na+/H+ antiporter

Question 5

reabsorption is not direct……

Answer 5

H+ secretion = HCO3- reabsorption

Question 6

To summarize: by the end of the proximal tubule –

Answer 6

K+ and divalent cations reabsorbed by solvent drag

bicarbonate reabsorbed due to activity of Na+ / H+ transporter

Question 7

In the ascending thick limb (ATL; see diagram at right), fluid is diluted via

Answer 7

Na+ K+ 2Cl- symporter in apical membrane

Na+ K+ ATPase in basolateral membrane

Question 8

ascending thick limb

paracellular transport of monovalents and divalents NOT due to

Answer 8

solvent drag. Tubular fluid becomes positive when Cl- reabsorbed so cations diffuse along an electrical gradient

Question 9

ATL
Fluid leaving loop is ——–, but the renal countercurrent mechanism has established an osmotic gradient required for formation of hyperosmotic urine. Concentration of the tubular fluid will occur in the collecting duct if antidiuretic hormone (ADH/vasopressin) is present.

Answer 9

hyposmotic

Question 10

More NH4+ can be added to the urine by diffusion trapping.

Much of the NH4+ leaving the proximal tubule is

Answer 10

reabsorbed by the ascending limb of the loop of Henle

Question 11

More NH4+ can be added to the urine by diffusion trapping.

NH4+ substitutes for———- and enters the interstitial fluid in the ——— where it is in equilibrium with NH3

Answer 11

K+ in the Na+K+2Cl- symporter

medulla

Question 12

NH4+ is produced in the ———- by metabolism of glutamine. The NH4+ that is produced is transported into the ———– and the HCO3- moves into blood.

Answer 12

proximal tubules

tubular fluid

Question 13

The peritubular capillaries are permeable to ——- so plasma osmolarity changes as the

Answer 13

NaCl and water

capillaries follow the loop, but the osmolarity of the blood leaving the kidney (to veins) is normal.

Question 14

The initial segment of the distal tubule, reabsorbs ~8% of filtered NaCl via a————- and———–

Answer 14

Na+ Cl- symporter in apical membrane

Na+ K+ ATPase in basolateral membrane

Question 15

There are two cell types in the collecting duct and late distal tubule

principal cells have

Answer 15

epithelial sodium channels (ENaC) that reabsorb Na+ and secrete K+

Question 16

There are two cell types in the collecting duct and late distal tubule

Principal cells
K+ secreted due to

Answer 16

Na+ K+ ATPase activity in basal membrane

Question 17

Principal cells

Na+ reabsorption drives

Answer 17

paracellular Cl- reabsorption

Question 18

There are two cell types in the collecting duct and late distal tubule

intercalated cells involved with acid-base balance; can also

Answer 18

reabsorb K+

Question 19

Hormonal regulation of blood volume -

Answer 19

ADH

Question 20

Actions of ADH
increases the permeability of the late ———— to water by increasing ——— into the apical membrane (basolateral membrane is freely permeable to water)

Answer 20

distal tubule and the collecting duct

aquaporins

Question 21

ADH

also increases permeability of

Answer 21

medullary collecting duct to urea

Question 22

ADH

If ADH low (diuresis) –

Answer 22

solutes reabsorbed in distal tubule and collecting duct, but no water reabsorption; urine as dilute as 50 mOsm/kg H2 O 18L pee

Question 23

If ADH high (antidiuresis) –

Answer 23

water reabsorbed as fluid passes through collecting duct; urine can be concentrated up to 1200 mOsm/kg H2O ½ L pee

Question 24

Alcohol inhibits

Answer 24

ADH secretion**

Question 25

How the system works…..

renin released in response to a drop in

Answer 25

perfusion pressure, decreased NaCl delivery to macula densa, or sympathetic input to juxtaglomerular cells

Question 26

aldosterone from the adrenal cortex acts to increase ———— in the distal tubule and collecting duct by increasing ————

Answer 26

NaCl reabsorption

transport protein synthesis

Question 27

Natriuretic peptides are hormones secreted when the

Answer 27

heart dilates (during volume expansion)

Question 28

Natriuretic peptides

Answer 28

Atrial natriuretic peptide from the atria

Brain natriuretic peptide from the ventricles (first found in brain)

Question 29

The effects of natriuretic peptides include

Answer 29

vasodilation of afferent arterioles

vasoconstriction of efferent arterioles

inhibition of renin (and aldosterone)

inhibition of ADH secretion

Question 30

Natriuretic peptide

Net effect is to increase the

Answer 30

excretion of NaCl and water.

Question 31

Why is potassium regulation important?

hyperkalemia will

Answer 31

depolarize Vm

Question 32

hypokalemia will

Answer 32

hyperpolarize Vm

Question 33

In the thick ascending limb have reabsorption of K+ by

Answer 33

Na+K+2Cl- symporter and paracellular transport (non-solvent drag)

Question 34

In the late distal tubule and collecting duct

K+ secreted by

Answer 34

principal cells depending on ATPase activity, K+ gradient, and/or apical K+ permeability

Question 35

Late distal tubule and collecting duct

—————- reabsorb K+ when potassium is depleted

Answer 35

intercalated cells

Question 36

Cells of the proximal tubule detect ——– can alter ———— accordingly.

Answer 36

intracellular pH and

CA activity

Question 37

Factors affecting excretion of potassium include

plasma [K+] - increased K+ stimulates

Answer 37

aldosterone release, and aldosterone increases Na+ K+ ATPases in principal cells

Question 38

Factors affecting excretion of potassium include

flow rate of tubular fluid –

Answer 38

increased flow rate increases K+ secretion

-local response to bending of cilia

Question 39

↑ flow —–> ↑ —— in collecting duct —> ↑ —– reabsorption —–> favors ↑ ———

Answer 39

Na+

Na+

K+ secretion

Question 40

nonvolatile acids

must be neutralized with

Answer 40

HCO3-

Question 41

nonvolatile acids

——— within tubular cells eliminates H+ and produces an HCO3- that is reabsorbed

Answer 41

ammonium production

Question 42

Bicarbonate reabsorption begins in the ———, and —– of filtered HCO3- is reabsorbed here.

Answer 42

proximal tubule

80%

Question 43

CA activity in the tubular epithelium produces H+ and HCO3-
H+ is secreted via ———-
also have ———— operating to secrete H+ (not illustrated)

Answer 43

Na+ / H+ antiporter

H+ ATPase pumps and H+/K+ ATPase pumps

Question 44

HCO3- is transported/reabsorbed across

Answer 44

basolateral membrane

Question 45

In the late distal tubule and the collecting duct CA activity in the ——— cells produces bicarbonate and H+

Answer 45

intercalated

Question 46

Intercalated cells

H+ is secreted via an

Answer 46

H+ ATPase pumps and an H+/K+ ATPase pump (not illustrated)

Question 47

A less common type of intercalated cell reverses the position of the

Answer 47

H+ and HCO3- transporters to the basolateral and apical membranes, respectively. These cells reabsorbs H+ and secretes HCO3- ; activity of this cell type is normally very low.

Question 48

If the body is alkaline, the kidney must produce alkaline urine which requires

Answer 48

incomplete reabsorption of HCO3- (figure on right)

increase excretion of HCO3- by not neutralizing all the HCO3- that is in the tubular fluid