case 8

Question 1

average pH of blood

Answer 1

7.4

Question 2

pH maybe death

Answer 2

below 6.8 or above 7.8

Question 3

3 buffer systems

Answer 3

carbonate, phosphate, proteins

Question 4

most important buffer

Answer 4

carbonic anhydrase

Question 5

chloric shift:

Answer 5

CO2 + H20 H2CO3 HCO3- + H30+

Question 6

carbonic acid information

Answer 6

H2CO3
conjugated base: HCO3-
pKa: 6.37
more conjugated base than acid. 10:1.

Question 7

phosphate buffer

Answer 7

hydrogen phosphate ion: HPO4 2-
dihydrogen phosphate ion: H2PO4-.
operates in 1,6:1 ratio. low concentration in ECF. inorganic phosphate is critical urinary buffer. concentration increases as fluid is resorbed.
H2PO4- H3O+ + HPO4 2-

Question 8

proteins

Answer 8

zwitterions: can react with themselves: NH2, COOH, COO-.
amphoteric: act as acids and bases.
ionizable groups –> bind or release H+.

Question 9

major extracellular protein buffers

Answer 9

serum albumin and plasma globulins. also hemoglobin.

Question 10

isohydric principle

Answer 10

buffers work together. in a solution with multiple buffers, all are in equilibrium at the same H+.

Question 11

chemical buffering

Answer 11

chemical buffers in EFC and ICF + bones. first line defense. minimizes change in pH, does not remove acid/base

Question 12

respiratory response

Answer 12

second line of defense. breathing removes CO2 loads of acid stimulates CO2 removal and lowers H2CO3 reducing acid.
regulated by chemoreceptors

Question 13

renal response

Answer 13

third line. removing excess H+. excreted in combination with urinary buffers. kidneys add new HCO3- to ECF to replace HCO3- used to buffer strong acids. also secrete anions (cl-, phosphate, sulfate). affect more slowely. urine is quite acidic. also removes negative ions

Question 14

exceptions

Answer 14

lungs can get rid of volatile acid and kidneys of nonvolatile acid.

Question 15

renal mechanisms

Answer 15

reabsorbing/creating HCO3-, excreting it.

Question 16

alkaline reserve

Answer 16

maintained by kidneys, not only by eliminating hydrogen to counter rising H+. exhausted stores of HCO3- have to be replenished. –> complex.
tubule impermeable to HCO3-. they can pass it generated within them into peritubular capillary blood. leaves the cell by NA+ of exhange for CL-.
N+ actively secreted by Na+-H+ antiporter but also by H+ ATPase.

Question 17

PCT

Answer 17

cells generate new bicarbonate ions with 2 mechanisms. involve renal excretion of acid.

Question 18

mechanism 1 PCT

Answer 18

phosphate buffer.
Type A intercalated cells secrete H+ active via H+ ATPase + K+-H+ antiporter. - H+ combines with HPO4 to form H2PO4- –> flows out of urine.
- HCO3- generated moves into interstitial space via HCO3-Cl- antiport and passively into peritubular capillary blood.
pK is 6.8 close to urine pH.

Question 19

mechanism 2 PCT

Answer 19

ammonium ions produced by glutamine metabolism.
NH4+ weak acids donate H+.
each glutamine –> 2 NH4+ + 2 HCO3-.
- HCO3- moves through basolateral membrane into blood
- NH4+ excreted and in urine.

Question 20

alkalosis

Answer 20

type B intercalated cells exhibit HCO3- secretion, while reclaiming H+.

Question 21

distal nephron

Answer 21

1. principal cells: reabsorb sodium + water and secreate postassium
2. intercalated: A cells –> secrete H+ and reabsorb HCO3-
   B cells: secrete HCO3- and reabsorb H+

Question 22

henderson-hasselbach

Answer 22

pH = Pka + log (conjugated base/ acid)

Question 23

acidosis

Answer 23

low pH –> denaturation

• glycolytic enzyme phosphofructokinase is pH dependent, decreases with decreasing pH, glucose utiliaztion in brain cells is impaired. –> coma
• impair normal organ functions. brought about by excessive accumulation of CO2.
• respiratory failure: complicated by presence of conditions that impair breathing
• shock of death

Question 24

alkalosis (causes)

Answer 24

• arrhythmia
• coma. breathing difficulties
• low potassium. imbalanced electrolytes.
  decrease in potassium –> hypokalemia.
• ## seizures.