PSL301 > PSL301: Water 7 > Flashcards

PSL301: Water 7 Flashcards

Acid-base balance (54 cards)

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1
Q

Acid can ___ H+

A

donate

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2
Q

Base can ___ H+

A

accept

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3
Q

conversion between pH and [H]

A

pH = -log[H]

[H] = 10^(-pH)

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4
Q

normal pH in blood

A
  1. 4

7. 35 - 7.45 range

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5
Q

most acidic part of body

A

stomach (1.5 pH)

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6
Q

most basic part of body fluid

A 
bile (pH = 8)
alkaline urine (pH = 8)
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7
Q

effect of diet on pH

A

protein - acidic

- sulfur-containing AA are metabolized to H2SO4

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8
Q

sulfur containing AA

A
  • cysteine

- methionine

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9
Q

1 Met or 1 Cys generates ___ H2SO4

A

1 mol

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10
Q

what prevents severe acidosis when we eat proteins?

A

buffers

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11
Q

BUFFERS

A

limit the change in [H] when an acid is added/removed from a solution

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12
Q

Buffers found in humans

A
  • bicarb (HCO3-)
  • phosphate (HPO4^2-)
  • ammonia (NH3)
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13
Q

the bicarbonate buffer system is catalyzed by…

A

carbonic anhydrase (CA)

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14
Q

Why is the bicarb system so good?

A

both sides of the equilibrium can be independently regulated; no other buffer system has this quality
- this allows for compensation

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15
Q

Kidney has 2 effects on bicarb

A
  1. make new bicarb

2. reabsorb filtered bicarb

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16
Q

New bicarb is generated by excretion of…

A

H+, buffered by ammonia or phosphate

  • NH4+
  • H2PO4
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17
Q

How does kidney make new bicarb?

A
  1. CO2 + H2O -> H+ and bicarb
  2. H+ is secreted into lumen, buffered by ammonia/phosphate
  3. bicarb is exchanged with Na+, reabsorbed into bloodstream
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18
Q

Where does the phosphate we use to buffer come from?

A
  • filtered from plasma

- diet

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19
Q

Mechanism of ammonia buffer system, from start to finish

A
  1. NH3 synthesized by proximal tubular cells
  2. Binds with H+, secreted into lumen as NH4+
  3. Reabsorbed in thick ascending limb
  4. NH3 diffuses through medulla
  5. Bind with H+ from MCD
  6. NH4+ trapped in CD lumen, excreted in urine
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20
Q

What is the more important urinary buffer? Why?

A

Ammonia;

  • Phosphate amount is limited and cannot be adjusted
  • Kidneys can regulate amount of ammonia 5-10x
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21
Q

ammonium is a weak ___

A

acid

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22
Q

___ freely diffuses across cell membranes & blood vessels

23
Q

___ does not readily cross cell membranes

24
Q

in a more acidic environment, there is more ammonia // ammonium

25
How does ammonia buffer H+?
1. Freely cross into lumen 2. Bind H+ inside lumen 3. NH4+ cannot cross back into tubular cell 4. must be excreted
26
ammonia is synthesized by the...
proximal tubular cells from Glutamine
27
For every 1 H+ / 1 NH4+ secreted, ___ bicarb is synthesized
1
28
How is H+ secreted by the CD?
H+-ATPase
29
Which AA makes ammonia?
glutamine
30
What regulates ammonium excretion?
acid/base status | - acidosis = ammonia synthesis & H+ secretion in CD (activate H+-ATPase)
31
Cell pH is recognized by ____, which then alters cell function to _____
cell receptors; | normalize pH
32
When is ammonium excretion increased?
- metabolic & respiratory acidosis | - higher protein intake
33
when there is a large acid load, ammonium excretion can increase ____ fold, but it takes ___ days to reach maximum
5-10; | 3-5
34
reabsorption of bicarb happens at...
proximal tubule
35
the best place to reabsorb large amounts of solute is at...
proximal tubule
36
main proximal tubule Na transporter
Na-H exchanger (NHE3)
37
for every 1 H+ secreted, ___ bicarb is reabsorbed
1
38
What is the drive for excreting H+ at the proximal tubule?
Na-K ATPase keeps intracellular Na+ low, so NHE3 pumps Na+ into cell in exchange for H+ into lumen
39
Difference in mechanism between bicarb reabsorption & regeneration?
regeneration: CO2 is from capillary reabsorption: CO2 is from lumen
40
most common acid-base disorder is...
metabolic acidosis
41
3 ways which metabolic acidosis can occur
1. addition of an acid not normally present 2. kidney can't secrete ammonium 3. loss of bicarb through diarrhea
42
Which acids cause metabolic acidosis?
- lactic acid - diabetic ketoacidosis - methanol poisoning (formic acid) - ethylene glycol poisoning (antifreeze) - salicylate poisoning (aspirin)
43
excess lactic acid may be the result of...
anaerobic glycolysis - exercise - shock (tissue not oxygenated) - liver failure (removes lactate)
44
formic acid can't be metabolized to...
CO2 and H2O
45
ethylene glycol is very dangerous because...
it forms poisonous metabolites
46
Why does lactic acidosis happen when there is not enough oxygen?
- build up of pyruvate - increased glycolysis to supply ATP - increase in NADH that want to be used up (minor effect)
47
Why might cardiac shock result in anaerobic respiration?
not enough O pumped by heart
48
causes of lactic acidosis
- low CO (shock) - hypoxemia - severe anemia - exercise - drugs that interfere w/ mitochondrial action - liver failure
49
site of lactate metabolism
liver
50
what happens if there is no respiratory compensation for metabolic acidosis / alkalosis?
then there is also respiratory acidosis / alkalosis
51
If toxic alcohols are present in blood stream, how do we cure it?
hemodialysis (has to be early enough)
52
main role of kidney in acid-base balance
maintain normal blood bicarbonate
53
kidney excretes ___ in order to make new bicarb lost to buffering
ammonium
54
the body responds to acid load by...
- buffer with bicarb (rapid) - hyperventilating to lower pCO2 (rapid) - excrete more ammonium (slow)
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