Kidney & Lung Buffering

Question 1

the kidney regulates production of ____

Answer 1

RBC

Question 2

when oxygen concentration is low, the kidney makes ____, which functions to…

Answer 2

erythropoietin
increase bone marrow production of RBC

Question 3

the kidney impacts absorption of ____ and ____ from the intestines in response to…

Answer 3

• Calcium & phosphorus
• response to PTH (low Ca or phosphorus in blood)

Question 4

what does PTH turn on?

Answer 4

enzyme 1 alpha hydroxylase

Question 5

what does enzyme 1 alpha hydroxylase do?

Answer 5

converts 25 hydroxycholecalciferol to 1,25 dihydroxycholecalciferol (calcitriol/1,25 (OH)2 vitamin D3) in the kidney

Question 6

what does calcitriol do?

Answer 6

increases both Ca and phosphorus absorption from intestines

Question 7

the kidney works with the lung to…

Answer 7

buffer the blood

Question 8

name the 3 buffer systems

Answer 8

1. bicarbonate buffer system
2. ammonia buffer system
3. phosphate buffer system

Question 9

what is the most important buffer system in the blood?

Answer 9

bicarbonate

Question 10

what does the bicarbonate buffer system respond to?

Answer 10

metabolic acidosis

Question 11

what does metabolic acidosis lead to?

Answer 11

acidic urine and increased respiration rate

Question 12

where does the bicarbonate buffer system occur?

Answer 12

intercalated cells of DCT and collecting duct

Question 13

what happens in the kidney in a high acid environment?

Answer 13

(bicarbonate buffer)
- H+ ions excreted in urine (decreases pH)
- bicarbonate ion reabsorbed from filtrate into blood

Question 14

what else must be excreted into urine to allow the bicarbonate ion to be reabsorbed, and what is this called?

Answer 14

chloride ion
chloride shift

Question 15

what does bicarbonate do when it is reabsorbed?

Answer 15

combined with other H+ ions to form carbonic acid

Question 16

what is carbonic acid converted to, and by what enzyme?

Answer 16

CO2 + H2O
carbonic anhydrase

Question 17

carbonic anhydrase is located in the ____ and requires ____

Answer 17

RBCs
zinc

Question 18

write the reaction for bicarbonate buffering

Answer 18

in capillary blood H + HCO3 -> H2CO3 -> (carbonic anhydrase/zinc) CO2 + H2O in lung

Question 19

both hydrogen and bicarbonate ions increase ____ in the ____, which is termed _____

Answer 19

• rate of respiration in the
• respiratory center of the brain
• compensatory respiratory alkalosis

Question 20

what system takes over when the bicarbonate buffer system is exceeded?

Answer 20

ammonia buffer system

Question 21

what is the mechanism of the ammonia buffer system?

Answer 21

• attaches 2 H+ ions to amino group of L-glutamine
• results in NH4 (ammonium ion)
• chloride ion excreted into urine, allows bicarbonate ion to be reabsorbed

Question 22

what system takes over when bicarbonate ions are exhausted, and what is its impact?

Answer 22

phosphate buffer system
bone demineralization

Question 23

type A intercalated cells in the collecting tubules secrete ____

Answer 23

H+

Question 24

in a person with chronic metabolic acidosis, what changes would you expect in
a) renal excretion of NH4Cl
b) urine pH
c) urine HCO3 excretion
d) plasma HCO3 concentration
e) plasma PCO2

Answer 24

a) increase
b) decrease
c) decrease
d) decrease
e) decrease