Renal Tubular Function

Question 1

What is a normal plasma glucose

Answer 1

70-110

Question 2

what classifies polyuria

Answer 2

> 2000 mL

Question 3

what classifies oligouria

Answer 3

<500mL

Question 4

what are the ways in which fluid and small solutes can cross the lumen barrier into interstitium to get to capillaries

Answer 4

paracellular via tight junctions

transcellular

Question 5

What are the various mechanisms of transcellular solute transport

Answer 5

simple diffusion
facilitate diffusion (carriers down gradient)
primary active transport (ATP hydrolysis)
seconday active transport (co or counter-transport)
pinocytosis- protein reabsorption

Question 6

What does the proximal tubule reabsorb

Answer 6

most filtered water, Na, K, cl, HCO3, Ca, phosphate and reabsorbs ALL filtered glucose, amino acids

Question 7

what are secreted in proximal tubule

Answer 7

organic anions and cations like drugs and their metabolites, creatinine and urate

Question 8

How come the osmolality never changes across tubule and plasma

Answer 8

because Na K and H2O are reabsorbed in equal quantities

Question 9

How can you determine the amount of filtered water that is reabsorbed in prox tubule based on the TF/plasma [ ] ratio

Answer 9

look at the inulin concentration ratio

Question 10

What does it suggest when PAH ratio is greater than the Inulin ratio on the T/F/plasma [ ] ratio

Answer 10

only secretion

Question 11

How come the inulin ratio is high in the TF/plasma [ ] ratio

Answer 11

because 2/3 water leaving but inulin is not reabsorbed so gets greater concentrated after water leaves into plasma

Question 12

describe the TF/P ratio of glucose in proximal tubule

Answer 12

becomes 0 because glucose is completely reabsorbed, more than water

Question 13

Which way does the NaK pump work and why

Answer 13

pumps Na out of cell and brings K in.
this is so there is a gradient for Na to enter cell from lumen so it can:
co transport glucose
counter transport H+ ions

in loop of henle co transports with K and 2Cl

Question 14

What is the mechanism causing reabsorption of urea and Cl

Answer 14

they become more concentrated because Na and H2O are leaving so the negative charges begin to repel eachother and drive themselves through the tight junctions into interstitium

Question 15

What is responsible for moving the solutes in the interstitium into the capillaries

Answer 15

bulk flow and starling forces resulting in net reabsorption

Question 16

what factors promote reabsorption in peritubular capillaries

Answer 16

high plasma colloid osmotic P

low hydrostatic P in capillaries

Question 17

What organ regulates plasma [ ] of glucose and AA

Answer 17

the liver and endocrine system

Question 18

By which mechanism is glucose and AA reabsorbed

Answer 18

secondary active transport, transcellular

Question 19

how does glucose and AA exit the luminal cell into interstitium

Answer 19

facilitated diffusion

Question 20

What limits the amount of glucose reabsorbed

Answer 20

number of Na glucose co transporters

Question 21

How do you calculate filtration rate of glucose

Answer 21

GFR times the Plasma glucose levels

Question 22

What is it called when there is glucose in the urine

Answer 22

glucosuria

Question 23

What disease does the saturation of glucose occur

Answer 23

DM

Question 24

what is tubular glucose maximum

Answer 24

rate of glucose reabsorption by all the nephrons combined

Question 25

What can change the threshold value of glucose absorption

Answer 25

the number of transporters

Question 26

why does urinary output increase in DM

Answer 26

becasue there is an increase of osmolarity in urinary filtrate so fluid will leave from plasma to try and normalize values
Osmotic diueresis

Question 27

Why is a patient with DM thirsty

Answer 27

plasma osmolarity increase

Question 28

What does an injection of mannitol do

Answer 28

it doesn not get reabsorbed so it sucks fluid into the lumen to decrease fluid levels in plasma.. used to decrease BP

Question 29

Why do you see an increase of Na in a patient with DM diuresis

Answer 29

because Na follows H2O

Question 30

What solutes utilize tertiary active transport and what is this

Answer 30

using 2 transporters to get out of intersititium

this is secretion of organic ions

Question 31

what drugs exit via the tertiary active transport method

Answer 31

penicillin, salicylates(aspirin), antiviral drugs

Question 32

Is PAH saturable

Answer 32

yes it can only secrete so much because # of transporters so the rest just goes through excretion

Question 33

When the clearance of PAH, and Glucose plateau what does this mean

Answer 33

plateau at GFR because hit carrier maximum

Question 34

what are secreted organic cations

Answer 34

catecholamines, acetylcholine and dopamine

Question 35

what type of secretion method is used for organic cations

Answer 35

rely on Na/K ATPase gradient

then flow down via a diffusion carrier

Question 36

what has to happen in order for organic cations and ions to be able to passively diffuse

Answer 36

need to be uncharged, less polar and more lipid soluble

Question 37

When is a weak acid more nuetral

Answer 37

when protonated

Question 38

when is a weak base more neutral

Answer 38

when deprotonated

Question 39

Hydogen ions in the lumen favors diffusion of what organic compounds into plasma

Answer 39

acids

not bases- favors excretion

Question 40

If a patient overdoses on aspirin how can you Tx

Answer 40

give patient bicarb so it stays in lumen and gets excreted