L21: Renal Acid-Base Regulation

Question 1

define acids

Answer 1

compounds that release H+

Question 2

strong vs. weak acids

Answer 2

strong acids dissociate completely

weak acids do not

Question 3

define bases

Answer 3

compounds that accept H+ ions

Question 4

volatile acids

Answer 4

CO2
bicarbonate
carbonic anhydrase

Question 5

volatile acids are excreted by the

Answer 5

lungs

Question 6

nonvolatile acids are excreted by the

Answer 6

kidneys

Question 7

nonvolatile acids

Answer 7

sulfuric acid
phosphoric acid
Ketoacids
lactic acid

Question 8

normal arterial vs. venous pH

Answer 8

art - 7.4
vein - 7.35

venous pH is lower/more acidic because it contains CO2

Question 9

list major systems in the body that regulate pH

Answer 9

1. buffer systems
2. lungs
3. kidneys

Question 10

define buffer

Answer 10

substance that can reversible bind H+

a weak acid

Question 11

list the buffer systems in the body

Answer 11

bicarbonate
phosphate
protein buffer system

Question 12

what buffer system is the most important extracell system?

Answer 12

bicarbonate

uses enzyme carbonic anhydrase

Question 13

how does the bicarbonate buffer system work when a strong acid or base is added?

Answer 13

acid – formation of weak acid

base – formation of weak base aka water

Question 14

buffer systems work to

Answer 14

minimize pH changes to maintain body pH

Question 15

what organ primarily regulates the bicarbonate buffer system

Answer 15

kidneys

Question 16

metabolic acid-base disorders relative to bicarbonate conc.

Answer 16

metabolic acidosis = decrease conc. of it

metabolic alkalosis = increase conc. of it

Question 17

respiratory acid-base disorders relative to pCO2

Answer 17

respiratory acidosis = increase in conc.

respiratory alkalosis = decrease in conc.

Question 18

relate normal pH point for bicarbonate buffer system w/ its pKa

Answer 18

pH = 6.1
when conc. of bicarbonate and CO2 are equal

thus pKa = pH at this point

Question 19

describe the phosphate buffer system role

Answer 19

plays a major role in buffering renal tubular fluid and intracell fluids

Question 20

why is the phosphate buffer system important to the kidneys

Answer 20

–phosphate usually becomes greatly conc. in kidneys

–lower pH of tubular fluid brings the operating range of the buffer closer to the pKa of phosphate buffer sys.

Question 21

main elements of phosphate buffer system

Answer 21

phosphoric acid

NaCl

Question 22

what is the primary method for removing nonvolatile acids

Answer 22

renal excretion

Question 23

what must happen before filtered bicarbonate can be reabsorbed?

Answer 23

must react w/ secreted H+ to form carbonic acid

carbonic anhydrase then splits it into CO2 and water

can then be reabsorbed into the cell

Question 24

H+ ion secretion via secondary active transport

Answer 24

Na/H antiporters
in almost all parts of renal tubules

except descending and ascending limbs

Question 25

H+ ion secretion via active transport

Answer 25

begins in late distal tubules in intercalated cells

H+ ATPase pumps

Question 26

where does bicarbonate reabsorption occur

Answer 26

80-90% of it occurs in proximal tubule

Question 27

intracell bicarbonate mvt

Answer 27

diffuses thru basolateral memb. into blood

Question 28

carbonic anhydrase is needed for

Answer 28

formation of carbonic acid from CO2 and water intracell

and splitting carbonic acid into CO2 and water extracell

Question 29

normally for every H+ ion formed a

Answer 29

bicarbonate ion is also formed and released into blood

Question 30

incomplete titration of H+ ions can result in

Answer 30

acidosis and alkalosis

Question 31

where are intercalated cells found

Answer 31

late distal tubules and collecting ducts

Question 32

what is the lower limit of pH that can be achieved in normal kidneys?

Answer 32

4.5

Question 33

every day the body produces ___ nonvolatile acids, mostly due to ?

Answer 33

80
mostly due to metabolism of proteins

and must be secreted by kidneys

Question 34

the loss of bicarbonate ion actually refers to ? not ?

Answer 34

the addition of H+ to blood

not an actual loss of a bicarbonate ion

Question 35

what limits the amount of free H+ ions that can be excreted in one day?

Answer 35

since urine pH can’t go lower than 4.5

you would have to urinate 2667 L a day to excrete 80 nonvolatile acids

Question 36

what buffers are important in allowing larger amounts of H+ ions to be excreted

Answer 36

phosphate buffer sys

ammonia buffer sys

Question 37

how does the phosphate buffer system combat excess H+

Answer 37

thru the production of new bicarbonates

Question 38

ammonia buffer system

Answer 38

production and secretion of ammonia ions by proximal tubular cells

exchange w/ glutamine to create new bicarbonate

Question 39

the ammonia buffer system depends on

Answer 39

protein metabolism

Question 40

alkalosis =

Answer 40

reduction in extracell fluid H+ ion conc.

Question 41

when does respiratory system acidosis occur

Answer 41

occurs when ratio of bicarbonate to CO2 in extracell decreases

Question 42

metabolic vs respiratory acidosis

Answer 42

ma = decreased bicarbonate

ra = increased CO2

Question 43

when does alkalosis occur

Answer 43

when there is an increase in the ratio of bicarbonate to H+ ion conc.

Question 44

metabolic vs respiratory alkalosis

Answer 44

ma = rise in extracell bicarbonate

ra = decrease in co2 conc.

Question 45

respiratory acidosis response

Answer 45

increase plasma bicarbonate ion due to addition of new bicarbonate by kidneys

Question 46

metabolic acidosis response

Answer 46

increase ventilation

renal compensation - adding new bicarbonate

Question 47

respiratory alkalosis response

Answer 47

reduce plasma bicarbonate conc. by excreting via kidneys

caused by hyperventilation

Question 48

metabolic alkalosis response

Answer 48

decreased ventilation

increased renal bicarbonate ion excretion

Question 49

who fixes metabolic and respiratory acidosis/alkalosis

Answer 49

kidneys fix respiratory

lungs fix metabolic