renal 4 - reabsorption, secretion, clearance

Question 1

which substances are only filtered

Answer 1

inulin and creatinine* (slightly different, creatinine is very slightly secreted)

Question 2

which substances are filtered and partially reabsorbed

Answer 2

electrolytes (Na, K)

Question 3

which substances are filtered and completely reabsorbed

Answer 3

glucose, amino acids

Question 4

which substances are filtered and completely secreted

Answer 4

organic acids (PAH, para-amino hippuric-acid) and bases

Question 5

what is inulin and where is it found

Answer 5

polysaccharide found in fruits and veggies

Question 6

which substances are completely or almost completely reabsorbed

Answer 6

water sodium (99%)
glucose (100%)

Question 7

is glucose physiologically regulated

Answer 7

no (not fine tuned hormonally)

Question 8

is water physiologically regulated

Answer 8

yes (fine tuned hormonally)

Question 9

is sodium physiologically regulated

Answer 9

yes (fine tuned hormonally)

Question 10

how is reabsorption mediated (LUMEN INTO CAPILLARY)

which is major and minor

Answer 10

mediated transport (transepithelial)MAJOR
diffusion across tight junction (paracellular)MINOR

Question 11

how does sodium get across the luminal/apical side

how

Answer 11

passive diffusion
high [Na+] in lumen vs cell

depends on area
counter transport, cotransport (prox. con, tub)
diffusion via Na+ channel CCD

Question 12

how does sodium get across the basolateral side

how

Answer 12

active transport by Na/K ATPase

Question 13

how does sodium get across the luminal/apical side in the proximal convoluted tubule

Answer 13

cotransport

passive

Question 14

how does sodium get across the luminal/apical side in the cortical collecting duct

Answer 14

diffusion via Na channel

Question 15

how does sodium get across the basolateral side in the proximal convoluted tubule

Answer 15

na k atp pump active

Question 16

how does sodium get across the interstitial fluid into the blood plasma

Answer 16

diffusion and bulk transport

Question 17

how does sodium get across the filtrate and into the interstitial fluid plasma

Answer 17

mediated transport

diffusion then na k atp ase

Question 18

what is the clearance of glucose

Answer 18

zero b/c non is voided in urine

Question 19

where is glucose reabsorbed

Answer 19

in the poximal tubule

Question 20

how is glucose reabsorbed

Answer 20

secondary active transport on the luminal side by SGLT

facilitated diffusion on the base-lateral side using GLUT

Question 21

what is glucosuria

Answer 21

glucose in urine

Question 22

when does glucose appear in the urine

Answer 22

above renal threshold

Question 23

why does glucosurea happen

Answer 23

the transport proteins are saturated

Question 24

what is transport maximum of glucose formula

Answer 24

limit of substance that can be transported/unit time

Question 25

what is renal threshold of glucose

Answer 25

the plasma concentration at which saturation occurs

Question 26

what happens at transport maximum of glucose

Answer 26

binding sites of transport proteins get saturated | filtered load exceeds the limit of reabsorption

Question 27

what is the renal threshold number

Answer 27

300mg/mL

Question 28

what is normal blood glucose levels

Answer 28

100-200mg/mL

Question 29

what happens in diabetes mellitus

Answer 29

capacity to reabsorb glucose is normal, but filtered load is beyond the threshold level to reabsorb glucose by the tubules [glu]blood high proteins all saturated

Question 30

what happens in renal glucosuria

Answer 30

mutation of Na/glu cotransporter that active reabsorbs glucose in prox. tubele

Question 31

how does glucose reabsorb in the prox tubules

Answer 31

active Na/glu cotransporter

Question 32

where does most of the water reabsorption happen

Answer 32

proximal convoluted tubule

Question 33

what does urea reabsorption depend on and why

Answer 33

water because water creates the concentration gradient which urea diffuses down (diffuse out of lumen)

Question 34

why does tubular secretion happen

Answer 34

whatever the body doesnt want, it gets another chance to get rid of

Question 35

what are commonly tubularly secreted substances

Answer 35

mostly H+ K+ | choline, creatinine, penicillin

Question 36

how are things tubular secreted

Answer 36

active transport coupled to reabsorption of Na+ (based on na k atp pump)

Question 37

what is renal clearance

Answer 37

way of quantifying kidney function in removing substances from plasma

Question 38

units for renal clearance

Answer 38

volume of plasma removed from kiney/ unit time ml/min or L/h

Question 39

what is the formula of clearance for substance S

Answer 39

S=UsV/Ps Ps=plasma conc Us=urinary conc

Question 40

what is the L/day of clearance of inulin

Answer 40

180L/day

Question 41

how can the clearance of inulin be used to measure GFR

Answer 41

Cin=GFR bc all is filtered out | GFF is inversly proportional to plasma concentration of inulin (GFR=UinV/Pin)

Question 42

what is creatinine

Answer 42

product of muscle metabolism

Question 43

how is creatinine handled in the kidneys

Answer 43

filtered, not reabsorbed, very slight secretion

Question 44

how can creatinine estimate GFR and what is the slight error

Answer 44

clearance of creatinine slightly over estimates GFR

Question 45

what does high creatinine mean

Answer 45

low GFR so the kidneys arent functioning right

Question 46

clearance of substance X>GFR

Answer 46

X undergoes secretion | more is cleared total than just by glom

Question 47

clearance of substance X

Answer 47

X undergoes reabsorption | more cleared by glom than is released

Question 48

how is Na transported in nephron

Answer 48

actively | Na K atp ase

Question 49

how is Cl transported in the nephrone

Answer 49

transported passively when Na is pumped out of the cell

Question 50

how is K transported in nephron

Answer 50

secreted into the tubules mainly by cells of the distal and collecting ducts

Question 51

where is the majority of solute excretion except for K+

Answer 51

proximal convoluted tubule

Question 52

where is most of the water and non waste plasma solutes reabsorbed

Answer 52

proximal convoluted tubule

Question 53

what does the loop of henle do

Answer 53

create osmotic gradient in medulla reabsorb large amounts of ions less water reabsorb

Question 54

what is the role of the distal convoluted tubule | what percent reabsorption

Answer 54

site of fine tuning of water and solute to produce urine | 12-15%

Question 55

where is there little water reabsorbed but lots of ions reabsorbed

Answer 55

loop of henle

Question 56

where is there 80% reabsorptive and secretory activities

Answer 56

proximal tubules

Question 57

where is there 12% reabsorptive activities

Answer 57

distal tubule

Question 58

where are most reabsorptive and secretory activities happening`

Answer 58

proximal tubules