Renal: Tubules

Question 1

describe the structures of the nephrons in order

Answer 1

bowmans capsule, proximal tubule, descending limb of loop of henle, loop of henle, asc limb of loop of henle, distal tubule, collecting duct

Question 2

what does the glomerulus do

Answer 2

filters a large vol of plasma water and solutes

Question 3

where does filtered fluid go

Answer 3

goes into the tubules

Question 4

what are the tubules responsible for

Answer 4

reabsorbing parts of the filtrate back into the blood, or secreting solutes to maintain proper composition and volume

Question 5

what is a normal gfr?

Answer 5

150L per day

Question 6

what is a normal urine volume

Answer 6

l per day0.5 - 2

Question 7

how much water gets reabsorbed by the tubules

Answer 7

99% of the water entering bowmans space gets reabsorbed by the tubules into the blood, letting kidney secrete waste but also conserve water

Question 8

explain the path of fluid from cardiac output to the bladder

Answer 8

output from heart, 20% goes to the kidneys, half of that to each kidney, 100% of this goes into the AA, 20% of that filters through into bowmans, 19% of this is reabsorbed into the peritubular cap, 1% gets excreted into environment

Question 9

how much sodium is filtered vs excreted in a day

Answer 9

22500 mmol filtered, only 150 mml excreted, therefore most of it is reabsorbed into the blood

Question 10

how much sodium must get reabsorbed in a day

Answer 10

more than 99%

Question 11

how does the fact that kidney cells are polarized help them reabsorb sodium?

Answer 11

they have different transport proteins on the luminal and basolateral (blood) membrane: so, each transporter only allows for transport in the direction that we want the sodium to go

Question 12

where is na k atpase localized

Answer 12

basolateral: makes sense this lets more sodium leave, and go back into the blood

Question 13

what do sodium hydrogen exchangers do

Answer 13

its an antiporter that moves sodium in from the lumen, and moves hydrogen out. once sodium is in the cell, since the nakatpase is maintaining a low intercell sodium conc, sodium now has no choice but to go through the basolateral transporter out into the interstit fluid

Question 14

what kind of transport protein is NHE

Answer 14

antiporter

Question 15

what is SGLT and its role

Answer 15

sodium co transporter. also in the lumenal membrane, moves in sodium with another molecule (glucose, phosphate, amino acids)

Question 16

what is NaP and its role

Answer 16

another sodium co transporter found on the lumenal side of PT cell, moves in sodium and phosphate into the PT cell

Question 17

what is ENac and its role

Answer 17

moves sodium in from high na conc lumen, water follows the sodium. its a CHANNEL not a transporter

Question 18

what is the importance of the na k atpase

Answer 18

maintains the low intercellular sodioum conc that NaP, SGLT and NHE depend upon

Question 19

describe the pathway of sodium in and out of the cell and how it may be impacted by dif transporters

Answer 19

sodium moves into the cell by way of the nhe (antiporter), sglt, nap (cotransporter), or enca (channel). it moves out of the cell through the basolateral nakatpase

Question 20

what are ways in which nephron segments differ

Answer 20

transport proteins, leakiness, tight junctions, aq channels, hormone receptors

Question 21

what happens in the proximal tubule

Answer 21

most na, cl, water, k , and bicarb reabsotion

Question 22

which transporter is found in the prox tubule

Answer 22

nhe, enac, sglt

Question 23

why is the prox tub leaky

Answer 23

so stuff can be reabsorbed

Question 24

what happens in the thick ascending limb of the loop of henle

Answer 24

about 20-30% of the soium gets reabsorbed, using the na k 2cl transporter.

Question 25

which tranport protein is found in the TAL? what does it do?

Answer 25

na k 2cl - moves sodium out of tal cells into medullary interstitium

Question 26

describe the fluid conc inside the TAL

Answer 26

fluid leaving the tal will be very hypotonic

Question 27

why does salt need to be added to medullary interstitium

Answer 27

it concentrates this area, which is necessary for tgetting the right urine concentration

Question 28

what happens in the distal convoluted tubule

Answer 28

5-10 % of filtered sodium and water gets reabsorbed.

Question 29

which transporter is found in the distal convoluted tubule

Answer 29

ncc (sodoium chloride co transporter)

Question 30

contrast function of thiazide vs furosemide

Answer 30

thiazides inhibit nccs, furoseminde inhibits na k cls

thiazides are less potent bc they deal with less sodium reabsorption than furosemide target

Question 31

what does the collecting duct do

Answer 31

reabsorbs 1-3% of the filtered sodium

Question 32

what transport protein is in the collecting duct

Answer 32

enac

Question 33

where are aldosterone receps found? role?

Answer 33

in the ccd, there increase the number of enacs, when we want to reabsorb more sodium back in (this would happen when you dont have enough sodium so you need to conserve!)

Question 34

where are vasopressin receps found? role?

Answer 34

also in the CCD, the increase the water reabsorption

Question 35

t/f: collecting duct cant make conc gradients

Answer 35

true

Question 36

contrast filtration vs reabsorption vs secretion

Answer 36

filtration is filtering from blood into tubule, reabs is from tubule back into blood, secretion is from blood/interstit (after secretion) back into the tubules

Question 37

what happens to glucose filtration as plasma glucose increases

Answer 37

flitration never saturates, higher plasma conc, higher filtration

Question 38

what point does glucose stop getting reabsorbed

Answer 38

once it hits the transport maximum, at which point it cant get reabsorbed back into the blood

Question 39

when does glucose start getting excreted

Answer 39

once you reach the transport maximum

Question 40

should there normally be glucose in the urine

Answer 40

no!

Question 41

how many na glucose transporters do we have? whats the dif?

Answer 41

na glucose symporter, which brings glucose into cell against gradient (two of these: one proximal, low affinity, high capacity and one distal: high affinity, low capacity)

glut transporter which transfers glucose out into ecf by diffusion

Question 42

how does glucose and na get in vs out of the cell

Answer 42

glucose: in with glucose na symporter, out with glut

na; in with sympoter, out with nakatpase